May 2006

Section 5 Gastrointestinal Tract and Abdomen

Benign Versus Malignant Disease

The differences between segmental colon resections done to treat benign disease and those done to treat malignancies are fundamentally important and may have a substantial effect on outcome. Accordingly, before specific techniques are described, it is worthwhile to review these differences, paying particular attention to the basic principles of and justifications for oncologic resections.

Resections for Benign Disease

Figure 1. Malignant and benign resections of the sigmoid colon

For patients with benign colon disease, removal of the diseased portion of the bowel in such a way as to leave uninvolved, healthy, and well-vascularized margins should be sufficient treatment. When indicated, the proximal and distal ends are anastomosed to restore continuity of the bowel. In these benign cases, dissection of the mesentery should be performed where it is easiest and most convenient. To this end, the major named branches are usually divided in their midportions: if the mesentery is divided within a few centimeters of the bowel wall, many of the small mesenteric branches will have to be ligated, which is inconvenient and time-consuming [see Figure 1].

Modern electrosurgical devices, such as the LigaSure vessel sealing system (Valleylab, Boulder, Colorado), can reliably seal mesenteric vessels as large as 7 mm in diameter without the traditional clamping and tying, and they can reduce operating times during more extensive colon resections (whether laparoscopic or open). The LigaSure Atlas and the LigaSure V use bipolar current and have a built-in knife that allows the surgeon to seal and divide the vessel in a single maneuver.

Figure 2. Early division of mesentery

Certain inflammatory conditions (e.g., Crohn disease and diverticulitis) may result in such severe pericolic inflammation and thickening that dissection of the mesentery close to the bowel wall may not be possible. In these cases, it may be necessary to perform a more radical mesenteric dissection in an area where the mesentery is softer. Severe inflammatory adhesions may cause the bowel to be stuck to the retroperitoneum, making the usual lateral mobilization of the colon nearly impossible. In these cases, early division of the mesentery (i.e., medial-to-lateral mobilization of the colon) may provide easier access to the proper plane of dissection, where the tissues are soft (i.e., in the retromesenteric plane anterior to Toldt's retroperitoneal fascia [see Figure 2]). This approach may help minimize the risk of injury to retroperitoneal organs (e.g., the ureter).

Resections for Malignant Disease

Colon resections for malignancy should include radical en bloc removal of the draining lymphovascular complex, with bowel margins wide enough to limit intraluminal and pericolic (lymphatic) recurrence. The drainage of the lymphatic system mirrors that of the vascular system. In the case of colon carcinomas, there are two possible directions for lymphatic drainage: (1) paraintestinal (along the intestine) and (2) central (along named mesenteric vessels). To prevent regional lymphatic recurrence, the major draining mesenteric vessel should be divided at the point of origin, together with the accompanying lymphatic network. If the tumor is equidistant from two named mesenteric vessels, both vessels should be ligated proximally.

Although, in most cases, intramural spreading of cancer should not exceed 2 cm,^1,2 an oncologic resection of the abdominal colon should aim at achieving proximal and distal margins of at least 5 to 10 cm to ensure adequate procurement of the epicolic and pericolic lymph nodes.^3,4 The two exceptions to this rule are in resection of rectal cancer, where a margin of 1 to 2 cm is accepted as part of a sphincter-saving operation, and in resection of a cecal carcinoma, where the ileum can be divided close to the ileocecal valve without compromising the oncologic outcome, provided that the lymphatic vessels along the ileocolic pedicle are removed. The ultimate length of the resected bowel segment is dictated by the lymphovascular resection. Large adenomatous polyps may harbor cancer, especially when they are villous, and resections for this indication should also include wide mesenteric clearance.

Oncologic principles There is increasing evidence that the quality of the operation done to treat colorectal carcinoma is directly correlated with the quality of the oncologic outcome. To date, the bulk of this evidence has come from studies of rectal carcinoma, but the correlation appears to hold true for colon cancer as well. In an excellent study carried out by the German Colon Cancer Study Group, the treating surgeon and the treating institution were found to be independent variables that affected both survival and locoregional recurrence after colon cancer resections.⁵

The concept that surgical technique may influence survival was first popularized in the 1960s. In a classic study (that has nonetheless been criticized for its uncontrolled methodology), Turnbull and associates retrospectively compared the outcomes of patients who underwent resections for malignancy that used the no-touch isolation technique with the outcomes of patients who underwent more traditional resections performed by other surgeons.⁶ The patients who underwent no-touch oncologic resections had a better 5-year survival. In the no-touch isolation technique, draining mesenteric vessels are ligated at their origin early in the dissection, and the bowel is divided proximal and distal to the lesion before the tumor is mobilized; as a result, the tumor is effectively isolated from intraluminal and hematogenous spillage during manipulation. This operative technique makes sense in the light of reports suggesting that malignant cells may be shed into the portal circulation during colon cancer operations (though the evidence for this phenomenon is still inconclusive).^7–9

To date, only one randomized, prospective trial has compared the no-touch isolation technique with conventional techniques for the curative treatment of colon cancer. In this trial, which involved 236 patients, there was no significant difference in 5-year survival between the no-touch group and the conventional group, though there was a trend toward better cancer-related survival in the former.¹⁰ Fewer liver metastases were observed in the no-touch group, and those that were observed seemed to develop later. This study was criticized on the grounds that the mean numbers of lymph nodes harvested were only 3.8 and 4.8 for conventional and no-touch operations, respectively, which raised questions about the quality of the oncologic resections. However, the authors pointed out that the study was designed to analyze only the effects of early lymphovascular isolation and that extensive lymphadenectomies were not performed.

Another randomized, prospective trial compared extended resections with segmental resections for treatment of carcinoma of the left colon. In this trial, 260 patients with cancer between the distal transverse colon and the rectosigmoid were randomly assigned to undergo either left hemicolectomy or segmental colectomy.¹¹ The lymphadenectomy done as part of the left hemicolectomy extended to the origin of the inferior mesenteric artery (IMA), whereas that done as part of the segmental colectomy was more limited, extending only to the region of the left colic artery (LCA). There was no difference in survival between the two groups, even when Dukes class C (TNM stage III) cancers were compared. Although a few retrospective studies have suggested that a more extensive lymphadenectomy improves survival, there remains some disagreement regarding whether true high ligation accomplishes this goal.^12–14 Intuitively, it would seem that high ligation should affect survival only in patients who have malignant lymph node involvement up to—but not past—the origin of the draining vessel. However, an adequate lymphadenectomy is undoubtedly important for accurate staging, and the current recommendation is that at least 13 lymph nodes should be harvested to ensure a high degree of staging accuracy.¹⁵

Although the quality of the operation does appear to affect the oncologic outcome, routine use of no-touch isolation for curative treatment of colon cancer is not currently an evidence-based practice. We believe that the risk of locoregional recurrences can be minimized by maintaining the following principles:

1. Wide mesenteric clearance, including high ligation of all draining mesenteric vessels.

2. Minimization of trauma to the tumor during mobilization.

3. Adequate proximal and distal bowel margins.

4. Wide clearance of tumor in cases of contiguous organ invasion.

5. Complete and accurate intraoperative exploration.

Figure 3. Resection of cecal and ascending colon

It can be argued that the no-touch isolation technique is an important component of oncologic surgical principles. Certainly, this technique adds little to the difficulty of the operation and can be performed without causing additional morbidity. We continue to employ the no-touch technique in the resection of colon carcinomas. Recommended resections of the abdominal colon for cancer depend on the location of the tumor [see Figure 3].

A growing number of reports have described short-term benefits of laparoscopy in treating benign conditions of the colon (e.g., diverticulitis, Crohn disease, and ulcerative colitis). Controlled studies performed by experienced surgeons have found laparoscopy to have advantages over open resection in terms of resolution of ileus, duration of hospitalization, level of postoperative pain, recovery of pulmonary function, and complication rates.^16–20 Even some cost analyses favor laparoscopic colectomy over conventional surgery, finding that the higher costs of the surgical instruments and the potentially longer operating times are outweighed by the shorter duration of hospitalization.^21–24 There also appears to be a lower incidence of surgical site complications after laparoscopy than after open surgery, as well as a lower incidence of postoperative adhesions (and thus, possibly, of subsequent small bowel obstruction).^25,26

Fear of port-site recurrences initially kept laparoscopy from being widely accepted in the treatment of colorectal carcinoma, but several randomized, controlled studies reported that the wound recurrence rates with laparoscopic resections were no different from those with open resections.^27–31 Particularly significant were the long-awaited results of the randomized, prospective trial carried out by the Clinical Outcomes of Surgical Therapy (COST) Study Group, which found the oncologic outcomes of open and laparoscopic surgery to be similar after a median follow-up period of 4.4 years.³¹ Also noteworthy was a randomized, prospective trial from Barcelona, which reported that cancer-related survival was actually better after laparoscopic surgery for colon cancer than after open surgery.²⁹ Further randomized trials are under way in Europe and Australia. These studies have helped lift the virtual moratorium on laparoscopic treatment of colorectal cancer, but surgeons must be reminded that they must first gain adequate laparoscopic experience with benign conditions of the colon before attempting laparoscopy for malignant disease.

Operative Technique

Step 1: Placement of Ports

Figure 4. Port placement for laparoscopic right hemicolectomy

The patient is placed in a modified lithotomy position. Four 5 mm ports and one 10 mm port are placed [see Figure 4]. The surgeon can stand either between the patient's legs or on the patient's left.

Step 2: Isolation of Ileocolic Pedicle

Figure 5. Laparascopic right hemicolectomy: dissection of ileocolic pedicle

The patient is moved into the Trendelenburg position, with the right side tilted up. The greater omentum is raised above the transverse colon, and the transverse colon is retracted superiorly. The terminal ileum is allowed to drop inferiorly toward the pelvis, and the proximal small bowel loops are swept to the patient's left. The duodenum is initially identified through the mesentery, just to the right of the superior mesenteric vessels at the angle between the transverse mesocolon and the right colonic mesentery. With anterolateral traction placed on the ileocecal junction, the ileocolic pedicle can be seen 'bowstringing' through the mesentery, just inferior to the duodenum. Studies of arterial anatomy show that the ileocolic artery (ICA) is a constant structure and that, in almost 90% of cases, the right colic artery (RCA) branches off from the ICA, not from the superior mesenteric artery (SMA). A window is made in the mesentery inferior and superior to the ileocolic pedicle, and the pedicle is dissected in the direction of its origin and ligated [see Figure 5]. Ligation can be accomplished by means of clips, vascular staplers, or the LigaSure Atlas; unless clips are used, the ICA and the ileocolic vein (ICV) can be ligated together.

Step 3: Dissection of Middle Colic Vessels

Next, the thin cut edge of the transverse mesocolon overlying the duodenum is grasped, and the duodenum is carefully swept down in a posterior direction. This measure initiates the medial-to-lateral mobilization of the transverse colon. The head of the pancreas is bluntly dissected, with care taken not to avulse the right colic vein or a branch of the inferior pancreaticoduodenal vein. A plane is gently developed to the right of the middle colic vessels. If this dissection proves difficult, the planned medial-to-lateral mobilization approach should be abandoned in favor of superior mobilization, and the omentum should be dissected off the transverse colon. In this way, access behind the middle colic artery (MCA) is facilitated.

Figure 6. Laparoscopic right hemicolectomy: isolation and division of right colic vein

The first vessel encountered to the right of the middle colic vessels is a venous branch to the right colic flexure. This branch converges with the right gastroepiploic vein (GEV) to form Henle's gastrocolic trunk, which empties into the superior mesenteric vein (SMV). The right colic vein (RCV) should be divided proximally so as to spare the right GEV. In some cases, an artery accompanies the RCV to the hepatic flexure; if present, this artery should be divided proximally, together with the vein [see Figure 6]. The peritoneum overlying the middle colic vasculature is then opened from right to left, and the right branch of the MCA is isolated and divided at its origin, with care taken to preserve the left branch. The anatomy of the MCA is quite variable, and the classic pattern of a single trunk that bifurcates into right and left branches occurs in only 46% of cases. Instead, one, two, or even three vessels may arise from the SMA to supply the transverse colon.

Figure 7. Laparoscopic right hemicolectomy: access to middle colic artery

In the case of an extended right hemicolectomy, the main trunk of the MCA should be divided at its takeoff from the SMA at the base of the pancreas. To this end, the peritoneum overlying the base of the middle colic vessels is opened from right to left, and a dissection plane is created to the left of the MCA [see Figure 7]. Access behind the middle colic vessels is best gained by proceeding from left to right, with the surgeon operating from the patient's left side. The middle colic vessels are isolated and divided at the appropriate level. After ligation of the middle colic vessels, an area of the transverse colon is chosen as the distal transection line, and the transverse mesocolon is divided in the direction of the bowel wall.

Step 4: Medial-to-Lateral Mobilization of Right Colon

Figure 8. Laparoscopic right hemicolectomy: medial-to-lateral retromesenteric dissection

The transverse mesocolon is then lifted anteriorly, and blunt medial-to-lateral dissection of the colon is performed, extending the previous dissection plane above the duodenum to the patient's right [see Figure 8]. Care should be taken to ensure that the dissection plane remains anterior to Toldt's retroperitoneal fascia (the white line of Toldt). The dissection is extended underneath the hepatic flexure, then underneath the right colon and the cecum. The right ureter should remain safely underneath an intact retroperitoneal fascia.

Step 5: Inferior Mobilization of Ileum and Lateral Mobilization of Right Colon

Figure 9. Laparoscopic right hemicolectomy: mobilization of right colon

Next, the terminal ileum is retracted out of the pelvis. With strong traction applied anteriorly and cephalad, the ileal attachment to the retroperitoneum is exposed and the peritoneum incised. If the medial dissection was adequate, this attachment will be thin; if not, the retroperitoneum may remain adherent to the cecum, in which case it will be necessary to identify the right ureter as it crosses over the right iliac vessels to ensure that it is not injured during mobilization. After the dissection has met the previous medial dissection plane, it is continued around the appendix and the cecum, and the lateral attachments of the right colon are taken down [see Figure 9]. Dissection of the hepatic flexure will become difficult with this approach. To resolve the difficulty, the patient is taken out of the Trendelenburg position, and the surgeon moves to the patient's left. The omentum is further dissected off the proximal transverse colon from left to right, and the takedown of the hepatic flexure is completed via this approach.

Step 6: Exteriorization, Resection, and Anastomosis

The appendix is grasped with a bowel clamp. A minilaparotomy is made, either as a midline extension of the umbilical port incision or in the epigastrium, depending on the transverse colon reach. It is usually about 5 cm long, but the size may be adjusted, depending on the size of the tumor. A wound protector is inserted to keep the surgical site from being contaminated by tumor. The mobilized right colon is then exteriorized.

Extracorporeally, the terminal ileum is cleaned and divided proximal to the ileocecal valve with a linear stapler. The ileal mesentery is dissected from the divided ileum toward the cut edge of the ileocolic pedicle, and the ileal and accessory ileal branches are ligated. The marginal artery of the transverse colon is ligated, and the transverse colon is divided with a linear stapler 5 to 10 cm distal to the tumor to liberate the specimen.

As in the equivalent open procedure, the anastomosis is then created extracorporeally with either handsewn stitches or staples. The bowel is replaced into the abdomen, and the minilaparotomy is closed.

The anastomosis between the ileum and the transverse colon can be created with any of several handsewn or stapled techniques (e.g., end-to end, end-to-side, side-to-side, or functional end-to-end). Basic anastomotic techniques are discussed in greater detail elsewhere [see 5:29 Intestinal Anastomosis]. For present purposes, it is sufficient to note that all of the various approaches to intestinal anastomosis, if constructed well, should yield essentially equal results in terms of postoperative function and rate of leakage. Whichever approach is adopted, it is essential that the cut ends of the bowel be well perfused. If bowel perfusion is in doubt, one should check for bleeding from the cut bowel edge or assess the marginal artery for pulses or bleeding. The mesenteric window need not be closed after creation of the anastomosis, because it is usually large and a mesenteric hernia with incarceration is exceedingly rare.

Troubleshooting

Step 1: Placement of Ports

Figure 10. Port placement for laparoscopic sigmoid colectomy

The patient is placed in a modified lithotomy position. Three or four 5 mm ports, one 10 mm port, and one 12 mm port are placed [see Figure 10]. When addressing the left lower quadrant, the surgeon stands to the patient's right, with the assistant standing to the patient's left. When mobilizing the splenic flexure, the surgeon stands between the patient's legs, with the assistant standing to the patient's right.

Step 2: Isolation and Division of Inferior Mesenteric Vessels

Figure 11. Laparoscopic sigmoid colectomy: creation of peritoneal window

The patient is moved into a steep Trendelenburg position, with the left side tilted up. With the medial-to-lateral approach to mobilization, the IMA is first approached medially. The sigmoid colon is retracted strongly out of the pelvis, and the sigmoid mesocolon is placed on anterolateral traction by the assistant. The initial dissection plane is just posterior to the IMA, where there is a clear avascular space, and the dissection is best begun at the sacral promontory. A wide peritoneal incision is made in the sigmoid mesentery [see Figure 11]. The right and left hypogastric nerves are swept away from the inferior mesenteric vessels in a posterior direction. The dissection plane is then extended laterally toward the abdominal wall, staying anterior to Toldt's retroperitoneal fascia. The left ureter must be identified before the next step is initiated; if it cannot be identified, it should be sought on the superior aspect of the LCA, or the approach should be changed to a lateral one. The IMA is isolated at its takeoff from the aorta and divided. The IMV is then isolated and divided proximally.

Figure 12. Laparoscopic sigmoid colectomy: medial-to-lateral retromesenteric dissection

Next, Toldt's retroperitoneal fascia is bluntly swept away from the posterior aspect of the left colon mesentery in a medial-to-lateral direction as far as the lateral abdominal wall. If the dissection is carried out in the correct plane, Gerota's fat will remain safely underneath Toldt's retroperitoneal fascia, as will the left ureter and the left gonadal vein [see Figure 12]. This retromesenteric dissection is then continued toward the upper pole of the kidney until it becomes difficult, at which point it is extended inferiorly toward the left psoas muscle and the iliac vessels.

Step 3: Lateral Mobilization of Left Colon and Takedown of Splenic Flexure

Figure 13. Laparoscopic sigmoid colectomy: mobilization of left colon

The sigmoid colon is retracted medially, and its attachment to the lateral abdominal wall is taken down. If the medial mobilization was adequately done underneath the sigmoid colon, the lateral attachment should be thin [see Figure 13]. The lateral ligament is divided cephalad, toward the splenic flexure. The attachments of the splenic flexure are complex; eventually, the splenocolic ligament, the so-called renocolic ligament (which is actually more a fusion of tissues than it is a ligament), and the omental attachments are mobilized. The inferior border of the pancreas has attachments to the transverse mesocolon, and this area should be dissected carefully so as not to injure the pancreatic tail, which sometimes, at first viewing, is difficult to distinguish from omental fat. A LigaSure Atlas or an ultrasonic dissector works especially well for limiting blood loss during takedown of the splenic flexure. The greater omentum is dissected off the distal transverse colon from right to left, the lesser sac is entered, and mobilization is continued laterally until it meets the previous dissection, at which point the flexure is completely mobilized.

Step 4: Distal Division, Exteriorization, and Proximal Division of Sigmoid Colon

The mesentery of the rectosigmoid is then mobilized, and the line of distal transection is determined. The hypogastric nerves should be assessed again to confirm that they are not stuck to the mesentery in this area. The upper mesorectum, including the superior hemorrhoidal vessels, is divided until the rectosigmoid wall is cleaned off. A laparoscopic linear stapler is inserted through the 12 mm port in the lower abdomen, and the rectosigmoid is divided. Division may require one or two firings and is facilitated by the use of an articulated rotating stapler. The cut end of the rectosigmoid is grasped with a bowel grasper placed through the right lower quadrant port.

Figure 14. Laparoscopic sigmoid colectomy: exteriorization of distal colon

A minilaparotomy is then created, either as an extension of the left lower quadrant port incision or as an extension of the umbilical port incision. As in a right hemicolectomy, the length of the minilaparotomy is tailored to the size of the tumor. A wound protector is inserted to prevent implantation of tumor cells, and the cut end of the specimen is exteriorized through the minilaparotomy [see Figure 14]. The sigmoid colon is brought out of the wound until at least 15 cm proximal to the tumor has been exteriorized. The colon is then divided so as to leave an adequate proximal margin, and the marginal artery is ligated at this level to liberate the specimen.

Step 5: Anastomosis

Next, the colon is prepared for anastomosis. A purse-string suture is placed into the open mouth of the colon, and the center rod and the anvil of a circular end-to-end anastomosis (EEA) stapler are inserted. The colon is placed back into the abdomen, and the minilaparotomy is closed.

Pneumoperitoneum is reestablished, and under laparoscopic visualization, a stapled circular anastomosis is fashioned between the proximal cut end and the rectosigmoid stump. A leak test is performed by instilling normal saline into the pelvis, occluding the bowel proximal to the anastomosis, and injecting air through a rigid proctoscope or a flexible sigmoidoscope. A final exploration is performed to confirm that the small bowel has not migrated underneath the left colon mesentery.

Difficulty Identifying IMA

Especially in obese patients, initial identification of the IMA can be difficult from the medial approach (with dissection either too posterior or too anterior), leading to a bloody and confusing mobilization. The problem can be minimized by first retracting the sigmoid colon strongly out of the pelvis, then retracting it anterolaterally. This action pulls the IMA pedicle anteriorly away from the surface of the aorta. The next step is to feel for the sacral promontory with laparoscopic instruments and start the dissection there; this site affords the easiest entry into the avascular plane posterior to the IMA. If the bony promontory cannot be palpated, the colon has not been adequately retracted. If the correct plane still cannot be identified, it is advisable to switch to the lateral approach.

Injury to Hypogastric Nerve Plexus

The right and left hypogastric nerves travel along the anterior surface of the aorta and over the aortic bifurcation, then spread out toward the pelvic sidewall. Branches of these nerves—and sometimes the main trunks—adhere to the posterior aspect of the inferior mesenteric pedicle and consequently may be transected when the IMA is divided. To keep this from occurring, these nerves must be visualized and swept away in a posterior direction. The initial mesenteric window should be made wide enough for adequate visualization. The surface of the aorta and its bifurcation should not be skeletonized.

Injury to Left Ureter

With the medial approach, it is easy to dissect too deeply, extending the plane underneath the left ureter and the left gonadal vein. Care should therefore be taken to search for Toldt's retroperitoneal fascia and stay anterior to it. Ideally, the left ureter should be identified before the IMA is ligated. If this is not possible, it is advisable to switch to the lateral approach and mobilize the sigmoid colon accordingly.

Tearing of Splenic Capsule during Splenic Flexure Mobilization

Avulsion of the splenic capsule is usually caused by traction. The capsule is most vulnerable to injury when the colon is in close proximity to the spleen. The risk of splenic injury may be reduced by either (1) early (posterior) dissection of the renocolic ligament before lateral mobilization of the splenic flexure or (2) dissection of the flexure close to the colonic wall. The early separation of the left kidney from the left colonic mesentery (with the dissection plane remaining anterior to the retroperitoneal fascia) causes the flexure to drop down, which widens the distance between the colon and the spleen. During mobilization of the splenocolic ligament and the greater omentum, it is important that the dissection not wander away from the colonic wall; if it does, the anatomy can become even more confusing.

Positive Anastomotic Leak Test

When a leak test yields positive results, the anastomosis must be repaired or revised. If the site of the bubbling from the anastomosis can be identified and is on the anterior aspect of the colon, sutures may be placed laparoscopically for repair, and the leak test should be repeated. If the site of the leak is hard to identify, the rectum distal to the anastomosis may be dissected and divided and the anastomosis refashioned; however, this can be a difficult procedure. In cases where laparoscopic repair is not feasible, a small laparotomy (either a Pfannenstiel incision or a low midline incision) may be made, and the problem may be addressed by means of open techniques.

A colorectal anastomosis is created between the proximal and distal cut edges of the bowel. For a double-stapled anastomosis [see 5:29 Intestinal Anastomosis], a purse-string suture is placed into the open mouth of the proximal bowel, the center rod and the anvil of a circular EEA stapler are inserted, and the purse-string suture is tied. The body of the stapler is advanced into the rectal stump, and the spike is pushed through the rectal wall. Once the proximal bowel has been checked to confirm that it is not twisted, the stapler is engaged and fired. A leak test of the anastomosis is then performed by instilling saline into the pelvis and gently infusing air into the bowel with a rigid proctoscope or a flexible sigmoidoscope while occluding the bowel proximally.

The anastomosis can also be created by means of a handsewn technique or a single-stapled technique (in which purse-string sutures are placed in both the proximal bowel and the distal bowel); these alternatives are described in more detail elsewhere [see 5:29 Intestinal Anastomosis]. In many cases, handsewn and stapling techniques may be equally suitable; however, for anastomoses fashioned lower in the pelvis, staples should be favored over sutures.