Sample Chapter

December 2007

Section 9 Care in Special Situations

Since the early 1990s, the number of live births in the United States has ranged from 3.88 to 4.12 million per year.¹ Complications related to nonobstetric surgery are relatively uncommon, occurring in only 1% to 2% of pregnancies.² Management of the pregnant patient differs from that of other patients in several ways. First, pregnancy induces a variety of mechanical, hormonal, and chemical alterations that may confuse and mislead even the most experienced surgeon [see Discussion, Physiologic Changes in Pregnant Patients, below]. Second, a surgeon's natural inclination, when faced with a pregnant patient experiencing abdominal pain, is to temporize. This tendency, which generally arises from the misconception that surgical intervention may injure the fetus, is responsible for delays in diagnosis and ultimately for the unfavorable outcomes often associated with acute abdominal pathology in pregnant patients. Third, pregnant patients require a multidisciplinary approach to care that involves the surgeon, the obstetrician, the radiologist, and the anesthesiologist. Finally, and most important, a surgeon treating a pregnant woman is actually caring for two patients and has the same responsibility to both.

In what follows, we first review urgent surgical problems in the pregnant patient, then discuss the physiologic changes of pregnancy and how these changes help shape general surgical principles in this population. Finally, we address certain nonurgent surgical problems associated with pregnancy.

Trauma is believed to occur in approximately 6% to 7% of gestations³—indeed, by some estimates, it may complicate as many as one in 12 pregnancies.⁴ Trauma remains the leading cause of maternal death, accounting for 46.3% of deaths during pregnancy.⁵ Homicide is the most common cause of traumatic maternal death, followed by motor vehicle accidents, accidental injury, and suicide.⁶ Motor vehicle accidents account for 55% to 66% of all trauma during pregnancy, falls account for 22%, and domestic abuse and assaults account for 21%. The more severe the injury to the mother, the greater the risk of injury to the fetus. When the mother survives, fetal death is most commonly related to abruptio placentae. Major trauma causes placental abruption in 40% to 66% of cases; minor trauma causes placental abruption in 5% of cases.⁷ Signs and symptoms of abruption typically become manifest within 4 hours of observation; however, a delayed presentation may also occur. In a patient with a history of trauma and potential abruption, persistent contractions are an indication for continued monitoring. Fetal death may also result from complications of premature delivery or from direct penetrating injury to the fetus.

Blunt Injury

In the mother, blunt trauma (as in motor vehicle accidents) may cause multiple life-threatening injuries, including head trauma, intra-abdominal hemorrhage, pelvic fracture, and uteroplacental vascular injury. Pelvic fractures are a particular concern: because of the extensive vascular supply in this area, there is a significant risk of substantial hidden blood loss. Because the uterus consumes approximately 20% of the cardiac output (i.e., 500 to 600 ml/min), a uterine injury can place a pregnant woman at substantial risk for massive hemorrhage within a short period. Uterine expansion displaces the bladder into the abdomen, thereby increasing the risk of traumatic bladder injury. The upper urinary tract is generally spared from injury, however, because the gravid uterus shields the retroperitoneum from direct injury. It should be kept in mind that mild hydroureter is physiologic in pregnancy. Hepatic, splenic, and uterine injuries are common in high-speed motor vehicle accidents, but injuries to the GI tract, surprisingly, appear to be uncommon, largely because of the protective effects of the gravid uterus.⁸ Direct injury to the fetus as a result of blunt trauma is unusual because of the protection afforded by the maternal abdominal wall and the uterus. Blunt trauma may result in fetal skull fractures, fetal intracranial hemorrhage, or abruptio placentae; nevertheless, fetal demise is rare in this setting and usually is secondary to maternal demise.

Many women refrain from using seat belts during pregnancy because of discomfort or out of concern that the seat belt might injure the fetus; however, this practice has no effect on fetal death rates in automobile accidents. When unbelted women are ejected from an automobile, maternal mortality is 33% and fetal mortality is 47%.⁹ Three-point restraint is the safest choice for pregnant women in motor vehicles.

Penetrating Injury

Penetrating injury is usually more damaging to the fetus than to the mother. Mortality is actually lower for pregnant women with penetrating injuries than for nonpregnant women with similar injuries, presumably because of the shielding effect of the uterus and the fetus.¹⁰

Penetrating trauma, however, often results in direct fetal injury. Fetal mortality in this setting ranges from 40% to 70%, whereas maternal mortality ranges from 5% to 10%.¹¹ In the first trimester, trauma generally poses little direct threat to fetal viability because the uterus is protected within the pelvis. In the second and third trimesters, however, when the uterus is located within the abdomen, penetrating trauma may result in direct fetal injury or rupture of the membranes. With penetrating abdominal trauma, the prognosis depends on which and how many organs are injured.

General principles of trauma management are applied when the need for laparotomy is under consideration. Visceral injury occurs 95% of the time if the peritoneum has been penetrated.¹² For this reason, many authorities advocate exploratory laparotomy for all high-velocity penetrating injuries to the abdomen. How best to manage low-velocity penetrating injuries remains somewhat controversial. Low-velocity injuries above the fundus of the uterus are almost always associated with visceral injury and thus call for exploratory laparotomy. Injuries occurring below the fundus and anteriorly are seldom associated with visceral injury⁸ and thus can generally be managed nonoperatively. Subsequent laparotomy is indicated for worsening maternal symptoms. Subsequent cesarean section is indicated for a viable fetus in distress.

Domestic or partner violence during pregnancy occurs in 7% to 23% of all pregnancies.¹³ If the patient is in an abusive relationship, the severity and frequency of assault typically increase during pregnancy.¹⁴ In addition, 20% of abused pregnant women attempt suicide¹⁵ or abuse alcohol or drugs. Abuse has many far-reaching consequences for the mother and the fetus that cannot be accurately measured. Unfortunately, partner violence often goes undiagnosed and hence untreated: as few as 12% of abused women are correctly identified in emergency room settings.¹⁶ Typical presentations of partner abuse include multiple injuries in various states of healing, inconsistent explanations of the injuries, minimization of the injuries, and delay in seeking medical attention.¹⁷ The face and the abdomen are struck more frequently during pregnancy. If a suspicion of partner violence arises, the physician should ask direct questions about threats and should provide appropriate contacts and support. A well-documented evaluation, unedited quotes, and careful drawings or pictures are also necessary in case the patient wishes to take legal action immediately or in the future. In all 50 states, domestic violence is a crime, and in some, failure to report suspected violence is a crime as well.

Management

Trauma is managed in essentially the same way in pregnant patients as in nonpregnant patients [see 7:1 Initial Management of Life-Threatening Trauma and 7 Trauma and Thermal Injury]. The mother is the first priority: stabilization of the mother improves both maternal and fetal survival. Initial measures include efforts to support the airway, breathing, and circulation (the ABCs). The physiologic alterations characteristic of pregnancy affect maternal responses to injury [see Discussion, Physiologic Changes in Pregnancy, below].

Hypovolemia can be masked by the increased blood volume and enhanced cardiac output of the pregnant patient. Tachycardia and hypotension may not be accurate indicators of hypovolemia: as much as 2 L, or 30% of maternal blood volume, may be lost before hemodynamic instability is detected.¹⁸ The expansion of intravascular fluid volume that occurs in pregnancy affects the amount of replacement fluid needed. In the third trimester, patients should receive 1.5 times the amount of fluid that would ordinarily be given to compensate for this effect. Use of military antishock trousers (MAST) may decrease maternal venous return by compressing the uterus on the inferior vena cava; accordingly, their use is not recommended. Vasoconstrictive agents should never be used for hemodynamic stabilization until hypovolemia has first been treated. Epinephrine and norepinephrine lead to uteroplacental vasoconstriction and fetal compromise; ephedrine and phenylephrine may be used during pregnancy.

Figure 1. Enlargement of the uterus during pregnancy

An important concern with advancing gestation is the possibility that the expansion of the gravid uterus [see Figure 1] can produce aortocaval compression, leading to supine hypotension. Left lateral displacement of the uterus is necessary to improve blood flow to both the mother and the fetus after the 20th week.

There are very few diagnostic procedures for which pregnancy is a contraindication. Radiographic investigation should be performed whenever necessary if the results are expected to affect management. It is usually possible to keep the total absorbed radiation dose below the level that is thought to increase teratogenic risk (i.e., 50 to 100 milliGrays [mGy]) [see Table 1].¹⁹ Plain films of the cervical spine provide useful information on head and neck injuries; computed tomographic scanning of the abdomen with contrast may offer the greatest amount of information on injuries to the retroperitoneum, the peritoneum, and the pelvis. Ultrasonography is now being used for acute trauma assessment in both pregnant and nonpregnant patients; the results to date have been good. Peritoneal lavage done in an open fashion through a supraumbilical incision may facilitate rapid assessment of intra-abdominal hemorrhage in cases of blunt trauma.²⁰ A Kleihauer-Betke test for fetal red blood cells in the maternal circulation will reveal any fetomaternal hemorrhage present. (Fetomaternal hemorrhage is the passage of fetal blood into the maternal vascular system; it occurs more frequently in pregnant women who have suffered traumatic injury than in those who have not, and it can lead to fetal anemia, arrhythmias, and fetal exsanguination.²¹) In Rh-negative mothers, a 300 µg dose of Rh_O(D) immune globulin will be protective against exposure to as much as 15 ml of fetal cells (30 ml of RhD-positive whole blood). Rarely does fetomaternal hemorrhage exceed this level. Tetanus toxoid should be administered when indicated.

Early determination of gestational age by means of ultrasonography is a critical guide to further management decisions. Ultrasonography can also be used to monitor fetal heart tones, fetal activity, and amniotic volume. After the 20th week of gestation, cardiotocographic monitoring is an important adjunct for determining fetal status after trauma. Such monitoring should also be employed in the event of preterm contractions. As many as 40% of women experience preterm contractions, but only 3% progress to premature delivery.⁷ Preterm contractions in a pregnant trauma patient should initiate an evaluation for abruptio placentae, uterine hemorrhage, and intra-abdominal hemorrhage. Given that placental abruption occurs in 66% of cases of major trauma and 5% of cases of minor trauma, the patient should be evaluated for ruptured membranes. Placental abruption usually occurs within 4 hours of injury. Ultrasonography is not sensitive enough to detect this condition²²; therefore, cardiotocographic monitoring should be continued for 4 to 6 hours after stabilization and longer if any irregularity in the mother or fetus is noted.²³ If the fetus has not yet reached the gestational age of 23 weeks or is not viable, the mother should receive supportive care. In these circumstances, cesarean section is reserved for cases of disseminated intravascular coagulation (DIC). If the fetus is viable and the mother stable, cesarean section can be carried out safely; if the fetus is viable and the mother unstable as a result of trauma, cesarean section should be carried out with the exploratory laparotomy.⁷ When the need for concurrent hysterotomy is under consideration, however, each case must be assessed individually. Typically, surgical intervention for a worrisome fetal heart tracing is not carried out until after the 24th week of pregnancy. Patients undergoing an emergency cesarean section should receive a broad-spectrum antibiotic preoperatively.

In the event of acute maternal decompensation that does not respond to standard resuscitative measures, a cesarean section may be appropriate. In cases of particularly severe trauma, emergency operative resuscitation should be considered. If the patient is in cardiac arrest, thoracotomy and open chest massage, with concurrent cesarean section if the fetus is viable, have been recommended.⁶ Cesarean section may increase maternal circulating volume. Occasionally, cardiopulmonary resuscitation (CPR) is more effective after the gravid uterus is emptied. There is also less risk of supine hypotension after cesarean section, though the associated surgical blood loss may exacerbate maternal instability. Timing is critical: if anoxia is limited to 4 to 6 minutes, the fetus generally will not be harmed. Therefore, any attempt to deliver the fetus should begin within 4 to 6 minutes after maternal cardiac arrest. If the fetus appears to be still viable after this period has passed, cesarean section should be performed; isolated cases of fetal salvage after prolonged maternal anoxia have been reported. The survival of the fetus after delivery is dependent on its having reached a gestational age greater than 28 weeks. CPR of the mother should be continued during and after the delivery because it may improve maternal status and survival.

Two caveats should be kept in mind: (1) cesarean section should not be performed in an unstable patient because of an anticipated cardiac arrest, and (2) if CPR is successful before surgical delivery is attempted, cesarean section should not be performed, because in utero resuscitation is likely.²⁴ In utero resuscitation may have to be continued for 10 to 20 minutes before reassuring elements reappear on a fetal heart tracing.

Appendicitis is the most common surgical problem in pregnancy, occurring in 0.05% to 0.1% of pregnancies, but it occurs no more often in pregnant women than in nonpregnant women.^25,26 The incidence is approximately the same in all three trimesters. The low maternal mortality—0.5% in 1977 and 0% in recent studies²⁷—notwithstanding, of all surgical problems during pregnancy, appendicitis causes the most fetal loss.²⁸ The particular dangers of appendicitis in pregnancy lie in the varied presentation of symptoms, the higher chance of delayed diagnosis, and the significant risk that surgery presents to the fetus.

The symptoms of appendicitis mimic symptoms of normal pregnancy—namely, anorexia, nausea, vomiting, and abdominal discomfort. The most reliable symptom of appendicitis during pregnancy is periumbilical or diffuse abdominal pain that later localizes to the right lower quadrant.²⁹ Although as the gravid uterus grows, it pushes the appendix cephalad and posteriorly, right lower quadrant pain remains the most consistent symptom of appendicitis in any trimester.²⁹

On physical examination, appendicitis presents with tenderness in the right lower quadrant. It can be differentiated from adnexal or uterine pain with the help of the Adler sign: if the point of maximal tenderness shifts medially with repositioning on the left lateral side, the etiology is generally adnexal or uterine. Abdominal guarding, rebound tenderness, or referred tenderness is present in 60% to 70% of patients with appendicitis; however, these findings are less common during the third trimester because of the laxity of the abdominal wall muscles.³⁰ Elevated body temperature is not a consistent finding in pregnant patients with appendicitis.^27,29

Laboratory values can be misleading, in that pregnancy can cause a leukocytosis as high as 15,000 leukocytes/mm³ in the absence of any source of infection.³¹ The white cell differential is more useful than the absolute count; increased levels of band cells or immature forms suggest that the leukocytosis may be secondary to an infectious process. A urinalysis is necessary to rule out a urinary tract infection, which occurs in 10% to 20% of pregnant women.

Diagnostic radiology should be employed deliberately and judiciously. Ultrasonography of the lower abdomen or transvaginal ultrasonography can often visualize an inflamed appendix without risk to the fetus. It can also distinguish other causes of abdominal pain, such as an ovarian cyst. The clinical presentation and an ultrasonogram are often sufficient to establish the diagnosis of appendicitis.^32,33

In very rare cases, a CT study of the pelvis should be done as well to elucidate a complicated presentation. A pelvic CT study yields a total radiation dose of 25 mGy, and a directed helical, or spiral, CT study yields a total exposure of 30 mGy. Directed spiral CT has a sensitivity and specificity of 98%.³⁴ For both pelvic CT and directed spiral CT, the total radiation doses are well below the threshold of safety established by the International Commission on Radiological Protection (ICRP), which is 100 mGy.³⁵ With plain films, the chance of obtaining valuable information is seldom worth the risk associated with the radiation. In certain cases, magnetic resonance imaging may be helpful for further delineation of the source of pain without the risk posed by ionizing radiation.

Because MRI does not expose the fetus to radiation and is known to be safe overall in the setting of pregnancy, it has become an increasingly attractive diagnostic imaging modality for identifying intra-abdominal pathology in the pregnant patient. Currently, MRI is also being used to help diagnose appendicitis. In one small series, MRI had an overall sensitivity of 100%, a specificity of 93.6%, and an accuracy of 94.0% in the evaluation of potential acute appendicitis.³⁶ Its negative predictive value was 100%. These results suggest that MRI is an excellent tool for excluding acute appendicitis in pregnant women with acute abdominal pain whose appendix cannot be visualized by means of ultrasonography.³⁶ This approach has not yet been widely accepted, and there is obviously a need for larger studies to confirm its value; however, the findings to date indicate that the use of MRI in obstetric patients with appendicitis is a promising strategy.

Differential Diagnosis

The condition most often confused with appendicitis is pyelonephritis, which occurs in 1% to 2% of pregnant women. The two diseases may present remarkably similar clinical pictures, especially when pyelonephritis occurs on the right side. Because of the mechanical effects of the gravid uterus on the ureter, pyelonephritis is more common in pregnant women than in nonpregnant ones. Furthermore, urinalysis yields abnormal results—either pyuria or hematuria—in as many as 20% of patients with appendicitis as a result of extraluminal irritation of the ureter by the inflamed appendix.³⁷ Nephrolithiasis can also be mistaken for appendicitis; it should be seriously considered whenever acute abdominal pain is present on the right side. Management of ureteral stones in pregnant patients presents a substantial challenge to both the surgeon and the urologist. Newer techniques, such as stenting³⁸ and placement of percutaneous nephrostomy tubes,³⁹ have been successful in obviating surgical intervention.

Right lower quadrant pain during early pregnancy may also be a presentation of ectopic implantation. Typically, a patient misses a period and then experiences some degree of vaginal bleeding or spotting. Abdominal or pelvic pain as well as cervical motion tenderness is present, and a mass is often appreciated on pelvic examination. When ectopic pregnancy is suspected, a serum human chorionic gonadotropin (hCG) assay should be performed along with transvaginal ultrasonography. If the serum hCG level is higher than 2,000 IU/L and an intrauterine gestational sac is not visualized by transvaginal ultrasonography, laparotomy or laparoscopy is indicated.

Torsion of an ovary or an ovarian cyst is also difficult to distinguish from appendicitis.⁴⁰ Although rare in pregnant patients, torsion of an ovarian cyst may occur in the early stages of the pregnancy. The physical examination is notable for pain in the right or left adnexa and the occasional presence of a tender mass. Transvaginal ultrasonography will frequently detect the cyst. Treatment requires laparotomy. The differential diagnosis of acute abdominal pain in pregnancy should also include ovarian cysts, mesenteric adenitis, degenerating fibroid tumors, salpingitis, inflammatory bowel disease, cholecystitis, ovarian vein thrombosis, ruptured corpus luteum, rectus hematoma, round ligament pain, abruptio placentae, chorioamnionitis, and adhesions.

Management

When there is evidence of appendicitis and no alternative diagnosis seems likely, operative intervention is warranted no matter what stage the pregnancy has reached.⁴¹ The risk of the procedure to mother and child is minimal in comparison to the risks posed by delayed diagnosis, perforation, and abscess formation. Appendectomy in a pregnant patient does not increase the incidence of congenital malformation or stillbirth.²⁶ With routine surgical management, maternal mortality is negligible and fetal mortality is 2% to 8%.^27,42 For a ruptured appendix, maternal mortality is 1% and fetal mortality is as high as 35%.^40,43 Negative laparotomy rates of 15% or lower are considered acceptable in the nonpregnant population, but negative laparotomy rates as high as 35% are considered acceptable in pregnant patients in the light of the grave consequences of delayed diagnosis.⁴³

For appendectomy in the pregnant patient, a right lower quadrant muscle-splitting approach should be employed over the point of maximal tenderness. With late trimester pregnancies, this point of maximal tenderness may be higher than the traditional McBurney's point [see 5:31 Appendectomy]. The patient should also be turned 30° to the left to reduce pressure on the inferior vena cava and to facilitate exposure of the cecum. If there is doubt about the diagnosis, a low midline incision or a right paramedian incision should be made, especially if the patient has diffuse peritonitis. If appendicitis is found at the time of laparotomy, no further investigation for other intra-abdominal processes should be performed; such investigation may disseminate the infectious process and lead to late pelvic or abdominal abscesses. If, however, appendicitis is not found, the surgeon should thoroughly examine the peritoneal contents on the right side of the abdomen, taking care to avoid exerting traction on the uterus, which might lead to preterm labor. Appendectomy is advisable to avoid later confusion. If perforation occurs, the abdomen should be irrigated and drained. Skin closure should be avoided if abscess, advanced perforation, or gangrene is encountered.

Laparoscopic appendectomy, like all laparoscopic procedures, is controversial in the setting of pregnancy [see Discussion, Laparoscopic Surgery in Pregnancy, below]. When the diagnosis of appendicitis is uncertain, a laparoscopic approach can help rule out salpingitis, adnexal mass, or ectopic pregnancy.³⁰ When diffuse peritonitis is present, however, laparoscopy is associated with higher complication rates than laparotomy is.³⁰ The ideal surgical approach to appendectomy during pregnancy remains to be determined. To date, no study of sufficient statistical power has shown the laparoscopic approach to possess any clear advantages, though some studies and some anecdotal experience have suggested that such advantages may exist.⁴⁴ In one retrospective series, complication rates did not differ statistically between patients who underwent laparoscopic appendectomy and those who went open appendectomy, but there were two cases of second-trimester fetal demise in the laparoscopy group, a finding that may be of concern.⁴⁵

For a laparoscopic appendectomy in a pregnant patient, the first trocar (i.e., that for the camera) is placed in the subxiphoid area under direct vision via an open technique; this step allows visualization of all pelvic structures and the appendix. Once the appendix has been visualized, the right upper quadrant and right lower quadrant trocars should be placed under direct vision. If the size and position of the uterus make laparoscopic appendectomy difficult or impractical, the camera can be used to help locate the best available spot for an open incision.⁴⁶

Antibiotics should be given preoperatively. Postoperative wound infection can be minimized if adequate attention is paid to aseptic technique and handling of tissues. If perforation, peritonitis, or abscess formation is noted, I.V. antibiotics should be administered.

The premature delivery rate for pregnant women undergoing appendectomy ranges from 13% to 22%; this increased rate may contribute to the lower birth weights reported after maternal appendectomy.^25,29 The risk of premature delivery is especially high during the first week after appendectomy. Given that tocolytics have never been shown to improve outcome in this setting, beta2-receptor agonists are a better choice³⁰; they are indicated when advanced appendicitis is suspected or when active contractions have been documented.

The incidence of bowel obstruction [see 5:4 Intestinal Obstruction] in pregnant patients ranges from one in 1,500 to one in 66,000.⁴⁷ The most common cause of small-bowel obstruction during pregnancy is adhesions, which account for 55% of cases; volvulus accounts for 25% of cases, with hernia, cancer, and intussusception accounting for the remainder.^48,49 As the incidence of operative procedures and the average age of the mother at gestation have risen, the likelihood of adhesive obstruction has risen as well. This problem may be further exacerbated by the hypomotility or dysmotility known to occur during pregnancy.⁵⁰ The need for laparotomy and lysis of adhesive bands during pregnancy is extremely low; however, when surgical management is necessary, fetal mortality is 26% and maternal mortality 5%. With intestinal obstruction, the main concern is to ensure that diagnosis is not delayed. Accordingly, any pregnant patient presenting with nausea, vomiting, and a history of abdominal surgery should be presumed to have a small-bowel obstruction until it is proved otherwise.

Large-bowel obstruction is less common than small-bowel obstruction but can be seen more often as pregnancy progresses. The most common cause of large-bowel obstruction is cecal or sigmoid volvulus. Volvulus during pregnancy is associated with a 21% to 43% mortality.⁵¹ Colonic pseudo-obstruction, or Ogilvie syndrome, has also been reported late in pregnancy or in the early puerperium.⁵² Striking colonic dilatation without anatomic obstruction is apparent, with gas filling the entire length of the colon from cecum to rectum. The danger of cecal perforation is high when the maximum diameter of the cecum exceeds 12 cm.

Management

Any sign of bowel ischemia or perforation in a pregnant patient with intestinal obstruction should prompt immediate operation. For small-bowel obstruction, a nasogastric tube should be inserted, fluid resuscitation should be initiated, a Foley catheter should be placed, and a full battery of blood tests should be performed, including assessment of blood gas levels and electrolyte levels and a complete blood count. Because of the leukocytosis known to occur in pregnancy, close attention should be paid to the differential blood count. Any sign of increasing acute-phase activity may suggest ischemia or perforation. Evaluation of acid-base status may also be useful in assessing bowel viability. A flat-plate and an upright abdominal film can confirm the diagnosis of small-bowel obstruction and rule out free air. The risk of radiation exposure to the fetus must be weighed against the potential morbidity and mortality of a missed diagnosis.

Once ischemia and perforation are ruled out, small-bowel obstruction should be treated with aggressive fluid resuscitation to ensure euvolemia and correction of electrolyte abnormalities. If long-term bowel rest is anticipated, total parenteral nutrition should be considered [see 8:23 Nutritional Support]. If conservative management does not lead to resolution, prompt operative intervention maximizes the chances of an excellent outcome for both fetus and mother.³⁰ A vertical incision allows the best exposure. The entire bowel must be examined for points of obstruction and assessed for viability. Segments of necrotic bowel should be resected, and an ostomy should be fashioned if necessary.

Large-bowel obstruction is usually caused by volvulus. Sigmoid volvulus can usually be reduced by rigid or flexible sigmoidoscopy. If sigmoidoscopy fails, operative intervention with bowel resection and possible colostomy is indicated.³⁰ Treatment of a recognized cecal volvulus involves prompt operative intervention, resection of any threatened bowel, and cecopexy to prevent recurrence.

Pseudo-obstruction should be managed initially with bowel rest, electrolyte replacement, and the placement of a rectal tube. If these conservative measures fail to reestablish normal peristaltic activity, colonoscopy and intraluminal aspiration of the gas-filled colon should be tried. This approach is effective in as many as 85% of cases; however, it should be undertaken only by a skilled endoscopist because the potential for iatrogenic perforation of the bowel is extremely high. If there is no change in the size of the colon after 72 hours, a cecostomy is indicated.

Spontaneous rupture during pregnancy can involve the liver, the kidney, the spleen, or the esophagus. Spontaneous hepatic rupture during pregnancy is extremely uncommon, occurring no more frequently than one in 50,000 pregnancies and perhaps as infrequently as one in 250,000 pregnancies.⁵³ It is thought to be an advanced development in preeclampsia or eclampsia. Abdominal trauma and events that increase intra-abdominal pressure (e.g., sudden coughing, sneezing, or unusually strong contractions) have also been implicated as causes of spontaneous rupture. Rupture may occur during the second or third trimester, during delivery, or even in the early postpartum period. Typically, it develops in older, multiparous women in the third trimester.⁵⁴ Patients present with several days of severe right upper quadrant or substernal pain radiating to the back. The pain may precede the actual rupture by as much as a few days. Nausea, vomiting, hypertension, coagulopathy, and thrombocytopenia are frequently present. In some cases of rupture, the patient presents with hypovolemic shock. A right upper quadrant ultrasonogram often visualizes the rupture or the preceding subcapsular hematoma.³⁰

A limited number of renal ruptures have been described in conjunction with hydronephrotic kidneys; they are thought to be secondary to the physiologic hydronephrosis seen in pregnancy. Ultrasonography is the best imaging technique for diagnosis of renal rupture.⁵⁵ Splenic rupture is the most common nonobstetric cause of intra-abdominal hemorrhage during gestation. It usually occurs in conjunction with splenic artery aneurysms or spontaneous capsular rupture. In most cases, it is probably secondary to the increased blood volume and splenic enlargement seen toward the later part of pregnancy. Esophageal rupture has also been described, generally in association with heavy vomiting. Patients report sudden epigastric pain on vomiting that may radiate to the back and the chest. X-rays may reveal air in the mediastinum. An upper GI series with water-soluble contrast material will demonstrate the site of the rupture. Although esophageal rupture is not more common in pregnancy, it may be associated with the frequent nausea and vomiting seen with hyperemesis gravidarum. Ultrasonography, radionuclide scanning, and, ultimately, angiography may be helpful in diagnosing rupture of the liver, the kidney, or the spleen.

Management

Prompt institution of volume support is essential, followed by emergency surgery and correction of any coagulopathy. Conservative management is reserved for stable patients with nonexpanding subcapsular hematomas. Serial ultrasonography is indicated. If adequate assessment of the hematoma, expanding hematoma, or rupture proves difficult or impossible, the patient should be taken to the OR for surgical treament.⁵⁶

Operative management of hepatic rupture or expanding hematoma involves debridement of nonviable liver, hemostasis with electrocoagulation or packing, and adequate drainage. Cesarean section should be performed simultaneously, depending on the gestational age and the likelihood of fetal survival. This maneuver, when indicated, is curative. Maternal mortality as high as 50% to 75% has been reported, even with prompt surgical intervention. Fetal mortality can be even higher, reaching nearly 80% in some series.⁵⁷ Renal rupture necessitates urgent operative exploration. Every effort should be made to salvage the ruptured kidney. Suspected splenic rupture necessitates immediate laparotomy and splenectomy. Esophageal rupture is treated with immediate repair through the left chest, if the injury is to the lower portion of the esophagus, or through the right chest, if the injury is to the upper portion.

Acute cholecystitis is the second most common nonobstetric emergency in pregnant women. Symptomatic gallstone disease is far more common in women than in men because of the differential effects of the sex steroids on bile lipid composition and cholesterol saturation.⁵⁸ The difference in incidence begins at menarche, increases during the childbearing years, and decreases at menopause. By the age of 75 years, at least 35% of women and 20% of men have gallstones.⁵⁹

Gallstone disease is a result of cholesterol supersaturation and biliary stasis, both of which are promoted by pregnancy.⁶⁰ The elevated estrogen levels during pregnancy increase cholesterol secretion by the liver. Estrogen enhances hepatic cholesterol uptake, increases cholesterol synthesis, and inhibits catabolism of cholesterol to bile acids. High concentrations of cholesterol in the bile overwhelm the solubilizing ability of bile salts, with the result that cholesterol stones form.⁶¹ Elevated progesterone levels lead to bile stasis and decreased gallbladder contraction. Progesterone also causes incomplete emptying of the gallbladder after stimulation by cholecystokinin (CCK).⁶² The mechanisms are not understood, but it is thought that progesterone may decrease gallbladder reactivity to CCK.⁶³ The decrease in small-bowel motility that occurs secondary to progesterone elevation may alter enterohepatic circulation and decrease bile acid return to the liver.⁶⁴ The balance of bile salts and cholesterol is further altered in such a way as to favor cholesterol supersaturation and stone formation. Pregnancy also alters the pool of bile acids. The decreased percentage of chenodeoxycholic acid and the increased percentage of cholic acid during pregnancy also promote stone formation.

The incidence of gallstone disease in pregnant women ranges from 3.3% to 12.2%65 and increases with gestational age; however, only 30% to 40% of patients with gallstones are symptomatic.⁶⁶ The relative infrequency of symptomatic biliary disease is a function of the natural history of gallstones and of the time required to precipitate sufficient stones to generate symptoms.⁶⁷ Management of biliary colic consists of conservative therapy—namely, hydration, bowel rest if necessary, analgesia, and fetal monitoring. In pregnant patients, elective cholecystectomy for symptomatic gallstone disease should be delayed until after delivery. Fewer than 11% of symptomatic patients progress to a more serious complication (e.g., cholecystitis, choledocholithiasis, or pancreatitis). Cholecystectomy during pregnancy is reserved for recurrent biliary colic or the aforementioned complications. It follows that cholecystectomy is rarely necessary in pregnant patients: it is undertaken once in every 10,000 live births.⁶⁸

Gallstone disease causes acute cholecystitis in only 0.05% to 0.08% of births.⁶⁸ The clinical symptoms of cholecystitis consist of epigastric or right upper quadrant pain, fever, nausea, vomiting, and occasional radiation of the pain into the right scapula. Physical findings include tenderness in the right upper quadrant and, occasionally, the Murphy sign. Elevated liver function test results indicate that complicated biliary tract disease or choledocholithiasis is likely; however, elevated alkaline phosphatase levels are seen in normal pregnancies and thus are diagnostically unhelpful.

Ultrasonography can diagnose gallstones and biliary ductal dilatation with an accuracy of 97%.⁶⁰ It can also detect pericholecystic fluid, reveal gallbladder wall thickening, and elicit a sonographic Murphy sign, all of which are characteristic of cholecystitis.⁶⁹ Radionuclide scans introduce the risk of fetal exposure to radiation. This risk almost always outweighs the potential value of any information to be gained from such a scan.

Differential Diagnosis

The differential diagnosis of cholecystitis includes appendicitis (see above), pyelonephritis, nephrolithiasis, acute pancreatitis (see below), myocardial infarction, gastroesophageal reflux disease (GERD), peptic ulcer disease (see below), hepatitis, and hepatic liver abscess. Significant hepatic syndromes can occur during pregnancy, such as intrahepatic cholestasis of pregnancy, acute fatty liver of pregnancy, infectious hepatitis, the hemolysis-elevated liver enzymes-low platelet count (HELLP) syndrome, and eclampsia.^70–72 These syndromes should be considered if the clinical signs and symptoms observed in a pregnant patient do not conform to the typical picture of gallstone disease.

Management

Initial management of cholecystitis is conservative, comprising I.V. hydration, bowel rest, administration of meperidine and antibiotics, fetal monitoring, and, if necessary, nasogastric decompression. This regimen is successful in 84% of patients.⁷³ Operative intervention is indicated in the presence of any of the following: failure of conservative management, recurrent disease, intractable nausea, maternal weight loss, fetal growth retardation, obstructive jaundice, gallstone pancreatitis, or peritonitis. Thus, serial monitoring of liver function test results and amylase levels is essential during conservative therapy.

If cholecystectomy during pregnancy is necessary but not urgent, it is best to perform the operation in the second trimester: fetal mortality from a first-trimester cholecystectomy can be as high as 12%.⁷⁴ The rate of fetal loss decreases through gestation; however, beginning in the third trimester, the risk of preterm labor increases. Symptomatic gallstone disease is also a reasonable indication for surgical management.^68,75 Half of patients with symptomatic gallstone disease require repeat hospitalizations; in addition, several investigators have found the incidence of spontaneous abortion, preterm labor, or premature delivery to be higher in patients treated nonoperatively than in those undergoing cholecystectomy.⁷⁶ If cholecystectomy is performed in the second or third trimester, fetal mortality is lower than 5%.⁷⁷

There remains a degree of controversy regarding the relative merits of conservative management and aggressive surgical intervention for patients with symptomatic gallbladder disease. In one study using a Markov decision analysis model that took into account all available English data, conservative (nonoperative) management was compared with laparoscopic cholecystectomy.⁷⁸ In the conservative management group, the estimated fetal mortality was 7%, and the recurrence rates were 55%, 55%, and 40% for the first, second, and third trimesters, respectively. The rate at which emergency surgery was necessary after nonoperative management was 19.5%. In the laparoscopic group, the estimated fetal mortality was 2.5%. Accordingly, the authors concluded that laparoscopic cholecystectomy was superior to nonoperative management of biliary tract disease in the setting of pregnancy.

Surgical treatment during pregnancy consists of either open or laparoscopic cholecystectomy [see 5:21 Cholecystectomy and Common Bile Duct Exploration]. The advantages of laparoscopic over open cholecystectomy include earlier recovery, earlier mobility, reduced use of narcotics, smaller incisions, and fewer surgical site infections.⁷⁶ When carried out with standard precautions, laparoscopic cholecystectomy does not increase the rate of fetal loss (5%) or of spontaneous abortion, nor does it have a greater adverse effect on birth weight, Apgar scores, or the rate of preterm delivery than open cholecystectomy does.⁷⁹ Laparoscopic cholecystectomy can be performed safely and effectively throughout pregnancy.^79,80

The literature from the past 16 years clearly supports minimally invasive operative management of symptomatic cholelithiasis in pregnant women. The second trimester seems to be the optimal time for a laparoscopic cholecystectomy: the uterus tends not to occlude the operative field as much as it does later in gestation. Conservative, nonoperative management may place the patient at risk for cholecystitis and gallstone pancreatitis, which are associated with increased morbidity and a greater likelihood of spontaneous fetal loss, preterm delivery, and repeated hospitalizations for symptomatic relief—developments that often end in operative management. Particular concerns with laparoscopic cholecystectomy include a 0% to 5% risk of fetal mortality, a 0.1% risk of maternal mortality, and as much as a 7% risk of preterm labor. Often, a pregnant woman who has undergone the procedure may experience increased uterine activity afterward; this can generally be controlled with tocolytic therapy as indicated. Prophylaxis against thromboembolism is recommended, with an appropriate dose of heparin administered preoperatively and pneumatic compression devices employed intraoperatively. The patient should be maintained in the left lateral decubitus position to prevent compression of the inferior vena cava by the gravid uterus. The Trendelenburg position should be used no more than is necessary. Ideally, a Hasson technique should be employed, with several trocars used for manipulation of the tissues and preferably with 30° scopes. The patient's end-tidal CO₂ should be monitored and kept between 25 and 33 mm Hg. If possible, the pneumoperitoneum should be kept to 10 to 15 mm Hg; this level of pressure is associated with the best outcomes for the procedure. General anesthesia is preferred; ideally, an obstetric anesthesiologist should be present.^81,82

Routine indications for conversion to open cholecystectomy apply, including uncontrolled bleeding and unclear anatomy. Additionally, conversion during pregnancy is indicated if the gravid uterus has expanded to the point where safe dissection of the gallbladder by laparoscopic means is impossible.^80,83–86 If the fetus shows signs of distress, deflation of the pneumoperitoneum and conversion to an open cholecystectomy may be necessary. Laparoscopic cholecystectomy is contraindicated in pregnant patients with gallstone pancreatitis.

In patients with choledocholithiasis, intervention should be performed without delay. The common bile duct (CBD) should be explored by means of endoscopic retrograde cholangiopancreatography (ERCP) [see 5:18 Gastrointestinal Endoscopy], with fluoroscopy used economically and lead aprons worn to shield the fetus.³⁰ ERCP with sphincterotomy successfully addresses choledocholithiasis without increasing fetal mortality or the rate of preterm delivery.⁸⁷ Surgical management of choledocholithiasis with open or laparoscopic cholecystectomy and CBD exploration should be reserved for patients in whom ERCP fails. Choledocholithiasis with right upper quadrant tenderness, fever, and jaundice (Charcot's triad) suggests cholangitis. The only treatment options for cholangitis when ERCP fails are open cholecystectomy and percutaneous intubation of bile ducts.⁸⁸ Intraoperative cholangiography can be used without problems after the second trimester,⁸⁹ provided that the fetus is shielded with lead during imaging to limit radiation exposure. Duct imaging should be reserved for patients who have risk factors for CBD stones (e.g., pancreatitis, a history of jaundice, or choledochal dilatation).³⁰

Pancreatitis is rare during pregnancy, occurring in every 1,000 to 10,000 pregnancies.⁶⁸ Its incidence, like that of gallstone disease, increases with gestational age. Associated gallstone disease is present in 70% to 90% of pregnant women presenting with pancreatitis.^68,87,90 Gallstone pancreatitis is associated with a maternal mortality of less than 37% and a fetal mortality of 10% to 60%.⁸⁹ In the nonpregnant population, pancreatitis is associated with biliary tract disease in only 40% of cases, with alcohol-induced pancreatitis accounting for another 40%. In pregnant patients, pancreatitis can be secondary to hypertriglyceridemia,⁹¹ as well as to thiazide administration and hyperparathyroidism.⁹² At present, there is little evidence to suggest that pregnancy itself is an etiologic mechanism in the development of pancreatitis.^93,94

The signs and symptoms of pancreatitis in pregnant women are indistinguishable from those seen in the general population. Patients report an unremitting, deep visceral pain that is usually midabdominal but may radiate into the back; nausea, vomiting, and anorexia are also typical symptoms. Findings in severe cases include hypotension, hypovolemia, and a rapid, thready pulse. Jaundice occurs in patients with CBD stones. The hallmark of the condition is diffuse abdominal pain combined with hyperamylasemia⁹⁵; amylase levels may approach 2,000 to 3,000 U/L and may be accompanied by lipase elevations.⁹⁶ Albumin, calcium, and bilirubin levels should be measured and liver function tests performed. The results should be interpreted with caution in the light of the alkaline phosphatase elevation known to occur in normal pregnancies. Ultrasonography should be undertaken with the aim of searching for evidence of cholelithiasis and choledocholithiasis. Visualization of the inflamed pancreatic head may be informative; however, this structure is often difficult to locate.

Management

Treatment should be aimed at correction of the hypovolemia that invariably accompanies pancreatitis.⁹⁷ Restriction of oral intake is necessary. In cases of intractable nausea, a nasogastric tube should be placed. Intramuscular administration of meperidine at a dosage of 50 to 75 mg every 3 to 4 hours provides adequate analgesia. Antibiotics should be reserved for treatment of a specific infectious complication. Calcium levels should be kept within the normal range. Arterial blood gases should be monitored as indicated. Prolonged pancreatitis may necessitate lengthy periods of bowel rest. During extended periods without oral feeding, pregnant women should be maintained on total I.V. hyperalimentation.⁹⁸

In patients with pancreatitis caused by extrahepatic biliary obstruction, endoscopic management has achieved excellent results. ERCP and sphincterotomy [see 5:18 Gastrointestinal Endoscopy] can both be performed safely during pregnancy. Definitive treatment with cholecystectomy and intraoperative cholangiography can safely be delayed until after delivery. Operative intervention should be reserved for patients with biliary obstruction in whom there is no evidence of stone passage. Efforts aimed at postponing operative intervention have been somewhat successful, though the recurrence rate approaches 50%. Early operative intervention has not been shown to improve fetal survival.⁹⁰ During the first trimester, loss of the fetus is common⁹⁹; however, in the second trimester, operative intervention has a good chance of yielding excellent results for both mother and fetus.¹⁰⁰ Although unusual, pseudocyst formation has been reported in pregnant women. It is managed conservatively, without operative intervention. Laparotomy, debridement, drainage, and cholecystectomy are indicated for severe cases with pancreatic necrosis.

Safe symptomatic relief can be achieved with direct-acting agents (bismuth salicylate, sucralfate, aluminum hydroxide, and magnesium hydroxide). H2 blockers and proton pump inhibitors are reserved for symptoms refractory to direct-acting agents. Most gastritis and ulcer disease is caused by infection by H. pylori. Treatment with the usual array of antibiotics (clarithromycin, amoxicillin, and metronidazole—but not tetracycline), direct-acting oral agents, and H₂ blockers is also safe in pregnancy.¹⁰¹ Limitation of intake of nonsteroidal anti-inflammatory drugs (NSAIDs), tobacco, and caffeine also helps mitigate symptoms.

A perforated duodenal ulcer must be treated surgically [see Urgent Surgical Problems, Perforated Duodenal Ulcer, above]. Surgery is also indicated if significant hemorrhage—necessitating transfusion of more than six units over a 24-hour period—is observed. In this setting, maternal mortality is 14% after operation; however, it is 44% if surgical treatment is not provided.¹⁰²

Pregnancy does not affect either ulcerative colitis or Crohn disease to any great degree, nor do these diseases affect the welfare of the fetus appreciably.^103–105 Active disease flare-ups are most common during the first trimester and during the early postpartum period.¹⁰⁶ In a review of pregnancies in patients with Crohn disease, the outcome of the pregnancy was not adversely affected by the disease.¹⁰⁷ Although patients with active disease generally had poorer outcomes, neither pregnancy nor therapy affected the course of the disease.

In addition to these frank forms of inflammatory bowel disease (IBD), ulcerative or granular proctitis may also occur in pregnancy. This poorly understood disorder is confined entirely to the distal 10 cm of the rectum. Endoscopically, the mucosa manifests multiple diffuse superficial ulcerations and friability. Above the distal 12 to 15 cm of the rectum, the mucosa assumes a normal appearance. Bleeding is observed, ranging from spotting with defecation to measurable loss. The disease is self-limited, almost never progressing to true IBD.

Management

Treatment of ulcerative colitis or Crohn disease involves administration of sulfadiazine, steroids, or both.¹⁰⁸ Treatment with both of these agents is often recommended.¹⁰⁹ Both steroids and sulfadiazine have been reported to cause congenital malformations in animal studies; however, because of the increased risk of fetal and maternal mortality in untreated cases of IBD, it is recommended that steroids and sulfadiazine be administered together as necessary to minimize the active effects of the disease.¹¹⁰

If the disease does not respond to medical management, operative intervention may be undertaken, but only as a last resort. In patients with ulcerative colitis, the most common indication for operation is toxic megacolon, which, if left untreated, can cause significant infant and maternal mortality. In patients with Crohn disease, the uncommon problems of abscess, fistula formation, and bowel obstruction may force operation; these conditions should be treated in the usual fashion. Greater reliance should be placed on fecal diversion in pregnant patients because of the increased risk of anastomotic dysfunction. Active Crohn disease may necessitate complete bowel rest and maintenance of nutrition by central I.V. feedings.^111,112

In any pregnant patient with inflammatory bowel disease, particularly Crohn disease, the mode of delivery must be carefully considered. If the patient has active Crohn disease with rectal involvement, vaginal delivery may be contraindicated, so as to avoid the potential consequence of rectovaginal fistula formation.

Patients with ulcerative or granular proctitis should not receive systemic treatment with steroids or sulfadiazine, because of the potential toxicity to the fetus. Steroid enemas or enemas concocted from an elixir preparation of sulfasalazine may be administered. Low-residue diets may help control particularly bothersome symptoms.

A variety of physiologic alterations occur during pregnancy. These include mechanical, hormonal, chemical, and hematologic changes [see Table 2] that are essential for maintenance of the pregnancy during the 40 weeks of gestation but that may also complicate the evaluation of abdominal problems in the pregnant patient.

The respiratory system undergoes several measurable changes as a result of the hormonal and physiologic influences of pregnancy. Elevated progesterone and estrogen levels cause blood volume and cardiac output to increase; as a result, pulmonary blood flow increases. With the added component of decreased blood albumin concentration and thus decreased oncotic pressure, mild lung edema may ensue.¹¹³ Progesterone also acts as a direct respiratory stimulant, increasing the chemosensitivity of the respiratory center to CO₂. Stimulation of respiratory drive by progesterone may be the cause of a substantial proportion of the respiratory changes seen in pregnancy. Progesterone levels rise from 25 ng/ml at 6 weeks to 150 ng/ml at term. Tidal volume increases by as much as 40% in pregnancy, thereby increasing minute ventilation. With the upward displacement of the diaphragm, the widening of the subcostal angle by about 50%, and the increase of about 5 cm in chest circumference, the result is a 20% decrease in the functional residual capacity (FRC), which reflects the amount of air remaining in the alveoli at the completion of expiration. As FRC decreases, gas exchange decreases as a consequence of alveolar collapse. This phenomenon has major implications for ventilation of the pregnant patient.¹¹⁴

In pregnant patients, both O₂ consumption and CO₂ production increase as gestation progresses. As the progesterone level rises, chemosensitivity to CO₂ and CO₂ production increase, and minute ventilation progressively rises by up to 30%.¹¹⁵ Progesterone and increased CO₂ production are the main forces behind the condition known as hyperpnea of pregnancy. This condition results in a reduction in arterial CO₂ tension (P_aCO₂) from 40 mm Hg to 34 mm Hg and an increase in arterial oxygen tension (P_aO₂) from 60 mm Hg to 100 mm Hg. This exaggerated gradient between the mother and the fetus facilitates efficient exchange of gases. With the decreased P_aCO₂, the pregnant patient also experiences respiratory alkalosis in relation to the fetus. The oxyhemoglobin dissociation curve is thus shifted to the right, again facilitating delivery of oxygen to the fetus. To prevent harmful pH increases, the kidneys respond appropriately by excreting bicarbonate. Respiratory alkalosis with compensatory metabolic acidosis is normal in pregnancy.

As pregnancy progresses, tidal volume rises as a result of the increased chest circumference. Although the growing uterus forces the diaphragm upward by as much as 4 cm, tidal volume is maintained, thanks to increased use of accessory muscles. By week 12 of gestation, FRC decreases by 10% to 25% as a result of decreased chest wall compliance. Relaxin, the hormone responsible for ligamentous relaxation of the pelvis, may also be responsible for laxity of the chest wall ligaments. As a consequence of this laxity, the subcostal angle increases from 68° to 103°.¹¹⁶

As many as 75% of pregnant women are affected by dyspnea. Dyspnea of pregnancy comprises mild pulmonary edema, increased breathing load, increased drive, and greater use of accessory muscles.¹¹³ It can complicate the assessment of any pregnant patient with an underlying surgical issue. In addition, pregnant women typically have decreased oxygen reserve and thus are subject to rapid development of hypoxia and hypercapnia with hypoventilation or apnea. This vulnerability becomes especially important when such patients undergo intubation and anesthesia. Although dyspnea is common in pregnancy, any obstetric patient who presents with acute shortness of breath should undergo a careful evaluation. Cardiovascular disease as a cause of dyspnea complicates 1% to 4% of pregnancies.¹¹⁷

During pregnancy, cardiac output rises by 30% to 50% [see Table 3]. This rise is attributable to an increased heart rate and, to a lesser extent, an increased stroke volume.¹¹⁸ The HR increase may begin as early as 6 weeks after conception¹¹⁹; by the third trimester, the HR is 15 to 20 beats/min faster than the baseline rate. The increase in the plasma volume may be as great as 50%. Despite the increases in cardiac output and blood volume, BP actually decreases because of the overwhelming effect of reduced systemic vascular resistance. BP reaches a nadir in the second trimester and returns to baseline levels by the time of delivery.¹²⁰

The gravid uterus may press on the inferior vena cava, decreasing venous return and causing cardiac output to decrease by as much as 30%. Pregnant women may even experience dizziness or syncope. To optimize cardiac output, the pregnant patient should be placed in the left lateral decubitus position.¹¹⁵

Cardiovascular evaluation of the pregnant patient must take into account the altered cardiac output, blood volume, HR, and BP. Hypovolemia may not manifest itself as tachycardia or hypotension, as would normally be predicted; alternatively, tachycardia of pregnancy may be mistaken for hemorrhage. Careful analysis of the data is necessary whenever hypovolemia is under consideration. Additionally, pregnancy-associated signs and symptoms may complicate any evaluation of concurrent heart disease [see Cardiovascular Conditions during Pregnancy, below].¹²¹

Appetite can vary greatly from one pregnant woman to another. The average increase in daily intake is 200 kcal/day during the first trimester. The recommended dietary allowance (RDA) is 300 kcal/day during pregnancy—more if the pregnant patient is an adolescent or especially physically active.¹²² As many as 70% of pregnant patients experience nausea and vomiting. Nausea of pregnancy, or morning sickness, frequently occurs between weeks 4 and 16 of gestation. Most patients respond to conservative treatment, including selective eating and avoidance of dehydration. Persistent nausea and vomiting, termed hyperemesis gravidarum, can lead to dehydration, electrolyte imbalance, and organ failure. It is important to exclude other possible causes of nausea before attributing symptoms to nausea of pregnancy. This condition can complicate the diagnosis of appendicitis, gallbladder disease, pancreatitis, or bowel obstruction.

Between 40% and 80% of pregnant women experience GERD.¹⁰¹ Esophagogastric junction tone decreases as intra-abdominal pressure increases, with reflux the result. In addition, under the influence of estrogen and progesterone, the stomach exhibits decreased motility and an increased emptying time. Transit through the small bowel and the colon is also slowed. Few gastrointestinal changes have a critical impact on pregnancy. It should be kept in mind, however, that prolonged emptying time and other effects of progesterone increase the likelihood of aspiration with general anesthesia.¹²³

Estrogens and progesterone are thought to influence cholestasis of pregnancy as well. The net effect of the two hormones is to increase the cholesterol concentration in bile. Estrogen also decreases bile flow. Progesterone promotes smooth muscle relaxation and stasis throughout the biliary system.¹²⁴ In the evaluation of cholestasis or any liver disease, it is important to remember that placental alkaline phosphatase can increase measured alkaline phosphatase levels by a factor of 3 or 4.

As cardiac output increases, the glomerular filtration rate increases by 30% to 50%. This increase reaches a peak at the end of the first trimester. Accordingly, creatinine clearance and blood urea nitrogen (BUN) levels fall by 25% over the first trimester. The kidneys themselves increase in size by 1.5 cm as a result of increased vascularity.¹²⁵ The ureters become dilated as a consequence of the relaxing effects of progesterone on smooth muscle.¹²⁶ Dextrorotation of the uterus causes further dilatation of the right ureter.

Normal pregnancy causes numerous changes in coagulation and fibrinolysis. Platelets become more reactive, and destruction is enhanced; to compensate, the pregnant patient increases production of platelets. Normal pregnancy increases hepatic and endothelial cell synthesis of many procoagulant factors. Pregnant women have normal anticoagulant factor levels except for a sharp decrease in protein S antigen and activity. In general, fibrinolytic activity is impaired during pregnancy; however, bleeding time and clotting time are unchanged. Overall, pregnancy is a hypercoagulable state.¹²⁷ The risk of thromboembolism doubles during pregnancy.¹²⁸ Accordingly, compression stockings should be used whenever surgical management is embarked on.

Leukocytosis is normally seen in pregnancy. What the net effect of a decrease in CD4⁺ cells, an increase in CD8⁺ cells, and an unchanged number of B cells may be remains somewhat controversial.¹²⁹ More important than the higher total number of cells is the altered activity exhibited by all leukocytes, a complicated picture that is still not fully understood.

Although pregnancy may appear to be an anemic state, it is not: blood volume actually increases (see above), and red cell mass rises by 30% [see Table 2].

The use of anesthesia in the course of an operation does not pose a teratogenic risk to the fetus.¹³⁰ Surgical treatment can be acceptably safe if appropriate attention is given to certain key perioperative considerations—namely, fetal monitoring, radiologic investigation, anesthesia, and the timing of the operation.

The fetal HR is routinely measured both preoperatively and postoperatively.¹³¹ Though the fetal HR can be heard 14 weeks after conception, it serves as an indicator of fetal oxygenation only after week 26. Specific fetal HR abnormalities—absence of variability, late or variable decelerations, and bradycardia—are predictive of impending fetal hypoxia, physical damage, or death. In the absence of these extreme (and hence obvious) fetal HR patterns, interpretation of fetal tracings can be complex.¹³² There are no conclusive data to suggest that any single monitoring technique reflects fetal outcome.¹³¹ Optimization of maternal physiologic status is more important than any mode of fetal monitoring.

The standard units of measure for radiation are the Gray (Gy) and the rad; 1 Gy is equivalent to 100 rad, and 1 rad thus is equivalent to 1 cGy or 10 mGy. The ICRP has stated that radiation doses lower than 100 mGy do not increase the risk of fetal death, malformation, or developmental delay.³⁵ Doses between 200 to 500 mGy during weeks 8 to 15 of gestation, however, result in measurable IQ reductions, and doses higher than 600 mGy result in growth retardation and CNS damage. Most diagnostic procedures fall within the accepted safe range. The average radiation dose from an abdominal x-ray is 1.4 mGy, that from an abdominal CT scan is 8.0 mGy, that from a pelvic CT scan is 25 mGy, and that from a selective spiral CT scan of the abdomen and the pelvis is 30 mGy.

In many instances, alternate diagnostic modalities that do not employ ionizing radiation, such as ultrasonography and MRI, are sufficient to determine the proper treatment. If, however, diagnostic radiation does prove necessary, the fetus should be shielded, radiation exposure should be minimized, and radiation doses should be carefully documented.¹³³ Careful cooperation with the radiologist will help limit radiation exposure. It is of particular importance that the patient be informed of the risks associated with radiation in comparison with the expected benefits of diagnostic radiation in her case.

The physiologic changes associated with pregnancy have implications for anesthetic management. As noted (see above), oxygen reserve decreases with pregnancy. Upon intubation, hypoxia and hypercapnia with hypoventilation or apnea may develop rapidly. In one clinical study of obstetric anesthesia, airway difficulties occurred in 7.9% of intubated patients, compared with 2.5% of nonintubated patients¹³⁴; it is noteworthy that the primary reasons for difficult intubation were airway anatomy and technique, just as would be the case in nonpregnant patients. During intubation, pregnant women are also at increased risk for gastric aspiration owing to the decreased esophagogastric sphincter tone. Because of this increased risk of aspiration, nasogastric suction should be freely employed. The stomach should be emptied before emergency procedures and continually decompressed throughout the operation and the early postoperative period.

Anesthesia can suppress the normal physiologic compensation for aortocaval compression, in which event hypotension can ensue. Positioning of the patient in a leftward tilt or the left lateral decubitus position can minimize hypotension.¹³¹ Liberal use of indwelling urinary catheters allows gross estimation of the adequacy of blood volume and splanchnic perfusion during general operative procedures. If intra-abdominal operation is necessary after weeks 12 to 16, the bladder must be decompressed to allow adequate exposure in the pelvis and the lower abdomen.

According to retrospective studies, all anesthetic, opioid, sedative-hypnotic, and anxiolytic agents pose some degree of risk to the fetus; none of them appears to be significantly more teratogenic or safer than any other.¹³¹ If vasopressors are necessary, ephedrine is the drug of choice, in that it causes less uterine vasoconstriction than epinephrine or norepinephrine does. Small doses of phenylephrine are also safe for use in pregnant women who are hypotensive [see Table 4].

If a surgical problem arises during pregnancy, the urgency of surgical treatment must be balanced against the risk such treatment poses to the mother and the fetus. Urgent procedures, such as appendectomy, should be carried out in the usual timely fashion [see Urgent Surgical Problems, above]: in such cases, the risks to both mother and fetus outweigh the risks of miscarriage and preterm labor. Semielective procedures are best done during the second trimester.⁷⁶ In the first trimester, when organogenesis is ongoing, concerns arise about the teratogenic risks of medications and surgical interventions. During the first trimester, surgical procedures are associated with a miscarriage rate of 12%; during the second trimester, this rate falls to 0% to 5.6%. The incidence of preterm labor with surgical procedures is 5% in the second trimester but rises to 30% to 40% in the third trimester.¹³⁵ Elective procedures should be delayed until 6 weeks after delivery.

Even though surgical procedures have been associated with a higher incidence of preterm labor, especially in the third trimester, routine prophylactic use of tocolytics is not recommended. Tocolytics have several side effects and have not been shown to improve outcome when used prophylactically. Tocolytics are best employed to treat active uterine irritability. Uterine irritability can also be reduced by controlling maternal pain and anxiety.¹³⁶

The role of laparoscopic surgery in the management of pregnant patients remains to be established. Most current recommendations are based on retrospective and animal studies. Laparoscopy would appear to offer some significant benefits. For example, it leads to rapid postoperative recovery and mobilization and thus reduces the risk of thromboembolism associated with pregnancy. Hospital stays are shorter and hospital costs lower.¹³⁷ Often, less narcotic analgesia is required during recovery, and fetal depression from narcotic exposure is thereby minimized. Because laparoscopic surgery makes use of smaller incisions, incisional hernias are less common, and there is less incision-related discomfort as a result of the growing uterus and increasing intra-abdominal pressure.¹³⁵ Moreover, laparoscopic surgery involves less manipulation of the uterus and so may be less likely to induce uterine irritability, preterm labor, premature delivery, or spontaneous abortion.⁴⁶ Finally, when the diagnosis is uncertain, the surgeon can often use laparoscopy to identify appendicitis, ovarian masses, ovarian torsion, and ectopic pregnancy.

Pregnancy adds a level of risk to any laparoscopic procedure. Insufflation with CO₂ and increased intra-abdominal pressure lead to decreased uterine blood flow, decreased maternal vena cava return, and decreased maternal functional residual capacity.^80,136 The combination of CO₂ pneumoperitoneum, the reverse Trendelenburg position, general anesthesia, and aortocaval compression by the gravid uterus can decrease maternal cardiac output by 50%.¹³⁷ Animal studies suggest that CO₂ pneumoperitoneum may also cause an increase in maternal P_aCO₂, resulting in maternal and fetal acidosis¹³⁸; however, there is active controversy as to whether these intraoperative alterations caused by CO₂ pneumoperitoneum actually affect fetal health.¹³⁹ Finally, when laparoscopic surgery is performed in a pregnant patient, the uterus is susceptible to direct damage, irritation, or penetration by a Veress needle or trocar.¹⁴⁰

Certain precautions can be taken to limit the risks associated with laparoscopic surgery during pregnancy.¹³⁵ Using the Trendelenburg position (or minimizing use of the reverse Trendelenburg position) and left uterine displacement enhance venous return. Keeping intra-abdominal pressure below 15 mm Hg can minimize the decreases in uterine blood flow, maternal inferior vena cava return, and maternal functional residual capacity. Limiting the duration of insufflation minimizes the risks associated with CO₂ pneumoperitoneum. During laparoscopy, a transvaginal Doppler transducer should be used for fetal monitoring when possible; any signs of distress can be combated by decreasing intra-abdominal pressure and hyperventilating the mother. Standard noninvasive monitoring methods (e.g., capnography) are sufficient guides to P_aCO₂ values in routine cases.¹⁴¹ Ventilation should be adjusted in accordance with maternal P_aCO₂ levels. Finally, penetrating injury to the uterus can be minimized by entering the abdomen under direct vision and applying upward countertraction of the abdominal wall while placing a Hasson trocar.⁴⁶

Currently, the general tendency is to limit laparoscopic surgery in pregnant women to the first 28 weeks of gestation. Later in pregnancy, when the uterus is no longer confined within the pelvis and the lower abdomen, laparoscopic surgery becomes substantially more difficult. Although laparoscopic surgery, like laparotomy, increases the likelihood of preterm labor, tocolytics should be administered only in the event of documented or perceived contractions; given the side effects of tocolytics, their prophylactic use is more worrisome than the potential risk of preterm contractions.⁷⁹

When appropriate precautions are employed, laparoscopy poses no more risk to either the mother or the fetus than laparotomy does.^76,140,142 Again, there are no significant differences between the two approaches with respect to preterm delivery rate, birth weight, Apgar score, growth restriction, infant mortality, or risk of fetal malformation.^79,136

The incidence of heart disease during pregnancy is 1.5%, with rheumatic heart disease accounting for 60% to 75% of cases.¹⁴³ The current trend in the United States, however, is that fewer pregnant women are presenting with rheumatic heart disease and more are presenting with congenital heart disease.¹²¹ Heart disease becomes an active issue during pregnancy because gestation places great stress on the cardiovascular system: cardiac output increases by 30% to 50%, HR by 15 to 20 beats/min, and plasma volume by 50%. Delivery places added stress on the heart as a result of physical exertion, pain, and drastic fluid shifts. There is some blood loss with delivery, but there is also an increase in venous return resulting from the release of the pressure imposed by the gravid uterus on the inferior vena cava. In addition, excess extracellular fluid is drawn into the vasculature after delivery. If the diseased heart has little reserve, pregnancy can push the patient into florid heart failure. Recognition of heart failure may be delayed because normal pregnant patients typically present with peripheral edema, dyspnea, and poor exercise tolerance.

During pregnancy, most cardiac morbidity and mortality is from dysrhythmia and congestive heart failure with pulmonary edema. In mitral stenosis, the most common cause is the rheumatic valvular lesion encountered in pregnancy. When the valvular area falls below 1.5 cm², filling of the left ventricle during diastole is severely limited, resulting in a fixed cardiac output. Patients with this condition cannot tolerate the cardiac strain imposed by pregnancy and may experience pulmonary edema or atrial fibrillation from an overdistended chamber. Prevention of tachycardia and maintenance of adequate left ventricular preload are essential. Medical treatment includes activity restriction, treatment of dysrhythmias, administration of beta blockers to control HR, and careful use of diuretics. Patients who remain symptomatic despite conservative treatment are candidates for surgical intervention during their pregnancy. Case reports involving more than 100 women have found percutaneous balloon mitral valvuloplasty to be safe during pregnancy. Ideally, these lesions would be repaired before pregnancy. Aortic stenosis also typically develops from rheumatic fever. Again, the major treatment concern is maintenance of cardiac output and adequate venous return. Patients with severe stenosis may be unable to maintain coronary or cerebral perfusion; angina, myocardial infarction, syncope, or sudden death may develop. Candidates for surgical correction include those with a valvular area smaller than 1 cm², a peak gradient higher than 75 mm Hg, or an ejection fraction lower than 55%. The time surrounding partuition is particularly risky for these patients. Current data show that patients who have aortic stenosis without coronary artery disease and who receive adequate care are at minimal risk of dying.¹⁴⁴

The most common indication for cardiac surgery during pregnancy is native valve disease (36%),¹⁴⁵ of which mitral stenosis is the variety most commonly encountered. Progressive failure from mitral stenosis can cause dysrhythmias that exacerbate symptoms. Pregnant women with aortic stenosis or hypertrophic cardiomyopathy may experience angina and syncope in addition to heart failure, and they tolerate arrhythmias poorly. Aortic disease is the second most common indication for cardiac surgery during pregnancy (31%). Aortic dissection and aneurysm are associated with hypertension, atherosclerosis, and connective tissue disorders (e.g., Marfan syndrome and Ehlers-Danlos syndrome). Approximately 50% of all aortic dissections in women younger than 40 years occur during pregnancy. Other indications for cardiac surgery during pregnancy are prosthetic valve dysfunction (14%), congenital anomalies (e.g., atrial and ventricular septal defects) (7%), pulmonary embolism (6%), cardiac tumors (4%), and coronary artery disease (2%). Overall, cardiac surgery is associated with a maternal mortality of 0% to 3% and a fetal mortality of 12% to 20%.^143,146 The outcome of a cardiovascular operation performed in a pregnant patient is affected by the indication for surgery, the condition of the mother, and the timing of the procedure in relation to the gestational age.¹⁴⁷

Management

Ideally, women of childbearing age who have heart disease should receive counseling before planned conception. Such counseling should address the risks of pregnancy, the issues related to anticoagulation, and the fetal mortality and morbidity associated with specific clinical situations. Any significant congenital heart condition should be corrected before pregnancy if possible. Vigilance for symptoms of heart failure should be an adjunct to routine prenatal care¹⁴⁸; if signs of failure develop, the patient should be hospitalized for treatment of volume overload, tachycardia, and possible dysrhythmias.¹⁴⁹ If aortic dissection is noted, hypertension should be controlled.

The question of the optimal timing of cardiac surgery during pregnancy introduces a potential maternal-fetal conflict of interest. On one hand, maternal mortality from cardiac surgery is lowest in the first trimester; delaying operative treatment increases maternal mortality substantially.¹⁴⁵ On the other hand, fetal mortality and morbidity from cardiac surgery are highest in the first trimester and decrease as gestation progresses. Hence, the issue of how to time surgical management so as to safeguard both mother and fetus as well as possible is still the subject of some debate. In general, operative intervention should be delayed until the fetus is deliverable, at which time cesarean section can be performed, followed by cardiac surgery or aortic surgery.^143,150 If it is necessary to perform a cardiac operation during the first or second trimester, precautions should be taken to minimize the effects of bypass on the fetus. High-flow, high-pressure bypass is favored by most surgeons, the rationale being that high rates are necessary during pregnancy to ensure perfusion to the fetus, especially in the context of a contracting uterus. Cardiotocographic monitoring should be instituted to measure the level of fetal stress during bypass. Bypass causes uterine contractions through dilution of progesterone, a natural inhibitor of uterine contractions. Patients with documented contractions should receive tocolytics.

Finally, any pregnant woman undergoing cardiac surgery should receive antibiotics as prophylaxis against endocarditis, the most lethal complication of such procedures.¹⁴⁵

Splenic artery aneurysms are rare, with an incidence of less than 1%. They are, however, four times more common in women than in men, and 25% of all splenic artery ruptures in women occur during pregnancy. Several factors contribute to the relatively high incidence of such ruptures in pregnant women. Splenic arterial pressure is unusually high during pregnancy as a result of the increased cardiac output, the increased blood volume, and the pressure placed on the abdominal aorta and the iliac arteries by the gravid uterus. Pregnancy is also believed to break down the connective tissue component of the arterial wall. Multiparous women in the third trimester are at highest risk for a ruptured splenic artery aneurysm. In the nonpregnant population, splenic artery rupture is associated with a 25% mortality; however, in pregnant women, it is associated with maternal and fetal mortalities ranging from 75% to 95%,¹⁵¹ mainly as a consequence of erroneous diagnosis. Upon diagnosis of rupture, immediate operative repair is necessary. If a splenic artery aneurysm larger than 2 cm is found in a woman of childbearing age, elective resection is indicated.¹⁵²

Renal artery aneurysms are uncommon, appearing in 0.09% of the population; most are diagnosed incidentally in the course of CT scanning done for other indications. Renal artery aneurysms not only are associated with brittle hypertension but also carry a high mortality when they rupture. Because of the connective tissue laxity that develops during pregnancy, the risk of rupture is higher in pregnant than in nonpregnant women. When renal artery rupture occurs, immediate operative repair of the aneurysm is necessary. The most important indication for surgery in this situation is hypertension and female gender; the size of the aneurysm is a secondary concern.¹⁵³

Cancer during pregnancy occurs in 0.07% to 0.1% of births.¹⁵⁴ The types most commonly encountered in this setting are breast cancer (19%), thyroid cancer (17%), cervical cancer (11%), Hodgkin disease (7%), and ovarian cancer (6%).¹⁵⁵ All cancers except for melanoma and hematologic tumors metastasize to the placenta but not to the fetus.^156,157 The major risk factor for malignancy during pregnancy is age greater than 40 years. Pregnant women with malignancies are more likely to experience complicated hospitalizations, as are their babies. Malignancy during pregnancy also increases the chances of low birth weight and premature labor.¹⁵⁵

The measures commonly employed to treat cancer—surgery, irradiation, and chemotherapy—all pose significant risks to the fetus, especially in the first trimester. The degree of risk associated with operation depends not only on the gestational age but also on the disease, the stage of the cancer, and the nature of the procedure. Chemotherapy during the first trimester can cause fetal malformations, premature delivery, and restricted fetal growth in as many as 25% of cases; however, chemotherapy during the second and third trimester generally has a favorable long-term outcome.¹⁵⁸ Finally, any radiation therapy administered is likely to exceed the safety threshold for fetal radiation exposure.

Thus, treatment of cancer in a pregnant woman should involve close coordination between the oncology team, the obstetrician, and possibly a neonatologist. The patient must be well informed regarding the overall risks of treatment, the specific risks to herself if some components of therapy are delayed, and the specific risks to the fetus associated with each type of therapy.

Pregnancy-associated breast cancer is defined as cancer diagnosed during pregnancy or up to 1 year after delivery. It is associated with a worse outcome than other types of breast cancer are. The poorer prognosis may be attributable to aggressive tumor growth in response to hormones of pregnancy. In addition, diagnosis of pregnancy-associated breast cancer is often delayed because of the normal hypertrophic thickening of the breast during pregnancy, the inability of mammography and ultrasonography to differentiate between normal breasts and breasts with malignancies in pregnant women, or the reluctance of surgeons to perform biopsies during pregnancy.¹⁵⁹

Management

Any suspicious breast mass should be aspirated to rule out the possibility that it is a cyst. If the mass disappears after aspiration, follow-up via physical examination is appropriate. Mammography is safe in pregnancy, exposing the fetus to only minimal amounts of radiation (0.07 to 0.2 mGy).¹⁶⁰ If the mass does not resolve, a core-needle biopsy or an open biopsy with local anesthesia should be performed [see 3:5 Breast Procedures], regardless of the stage of pregnancy. Strict attention to hemostasis and to ligature of obvious ductules is necessary to prevent postoperative hematoma or leakage of milk. Another common presentation is nipple discharge [see 3:9 Benign Breast Disease], which may signal a papilloma or duct ectasia and thus calls for biopsy. Inflammatory changes in breast skin are generally caused by staphylococcal or streptococcal infections; they occur most frequently in the postpartum period but also are occasionally seen during pregnancy. If inflammation does not resolve rapidly after antibiotics are administered, drainage is indicated and biopsy should be considered.

Management of breast cancer in pregnant patients does not vary greatly from that in nonpregnant patients [see 3:1 Breast Cancer].¹⁶¹ Once the diagnosis of breast cancer is made, modified radical mastectomy [see 3:5 Breast Procedures] should be done expeditiously; it should not be delayed because of the pregnancy.¹⁵⁹ Given the high doses required, radiation therapy is contraindicated during pregnancy. Accordingly, lumpectomy with radiation therapy is an option only if radiation therapy can commence after delivery. As noted, chemotherapy is relatively safe during the second and third trimesters. For patients with stage III or IV breast cancer, termination of pregnancy may be considered to allow unrestricted treatment with chemotherapy and radiation. For all patients, treatment plans should be formulated on an individual basis, taking into account the risks facing both the fetus and the mother.

Burns occurring during pregnancy should be evaluated in the same manner as burns occurring in the nonpregnant population [see 7 Trauma and Thermal Injury]. The total body surface (TBS) burned should be measured and documented (ideally with photographs). Adjustments must be made for the increased abdominal surface area seen in the later stages of gestation. Fetal outcome is dependent on the mother's condition: fetal mortality is 89% when the mother has burns over more than 50% of her TBS but falls to 21% when the mother has burns over less than 50% of her TBS.¹⁶²

Generally, burns are treated in much the same way in pregnant patients as in nonpregnant patients; however, special attention should be paid to securing the airway and ensuring adequate breathing. Because pregnant patients have a lower FRC, they are less able to compensate for hypoxia. Moreover, exposure to burns often puts the mother at risk for carbon monoxide inhalation. The fetus is especially susceptible to carbon monoxide poisoning because fetal hemoglobin has a higher affinity for carbon monoxide than maternal hemoglobin does; thus, carbon monoxide can easily lead to fetal hypoxia.¹⁶³ Silver sulfadiazine cream should not be used near term because of its association with kernicterus in the infant. Finally, if the fetus is older than 24 weeks and the mother sustains burns over 50% or more of her TBS, cesarean section is indicated.

Electrical accidents ar