Improved Outcomes in Colon and Rectal Surgery part 7 pps

 improved outcomes in colon and rectal surgery A more difficult or dense adhesion can be approached from differ- ent angles to help define the appropriate plane. Oftentimes, simpler adhesions can be taken down on either side or even behind the dense adhesion to help delineate the proper path of dissection. Placing one’s fingers on either side of the adhesion and palpating can be of assistance to feel the plane and also sometimes stretch out the adhesion for easier division. Of course, one of the biggest keys to success is proper traction and counter-traction. If the traction is too forceful though, tearing of the bowel may occur. If an enterotomy does occur, it should be repaired immediately with absorbable sutures to minimize contamination. If the case is difficult and more injuries are predicted, temporary closure can be employed until all adhesiolysis is complete. A segment of bowel with extensive injuries may be best resected. Waiting until all injuries have been identified and a plan made can save sig- nificant time on unnecessary repairs. Sometimes dissection can be performed in an extraperitoneal plane to avoid bowel injury, leaving peritoneum adherent to the bowel wall. Other times a small piece of bowel wall may be left behind, adherent to a more critical structure, such as the ureter or iliac vessels, in order to avoid morbid injury at these crucial sites. Leaving devascularized bowel serosa or muscularis in-situ is not a problem. Any mucosa left behind, however, should be desiccated with electrocautery to prevent formation of mucoceles or malignancy. Consideration should be given in each case to preventing adhe- sions, which lowers the risk of bowel obstruction and makes any future surgeries easier. Adhesion formation is a local response of the peritoneum and pertonealized structures to ischemia, desiccation, or trauma and may form as result of the primary disease process or due to contact with surgical instruments, staples, suture, gloves, sponges, and other irritants introduced at the time of surgery. It is assumed that laparoscopy can minimize some of these insults by limiting bowel manipulation and exposure of the peritoneal surface to potential irritants.(28–30) Preliminary evidence in this regard can be found by noting that laparoscopic assisted ileocolic resection is associated with reduced rate of bowel obstruction when compared to open surgery.(31, 32) Adhesions to the anterior abdominal wall are minimal or absent.(33) (See Figures 6.3 and 6.4) (34) Additionally, the CO2 pneumoperitoneum is felt to be protective of certain types of injury.(35, 36) Initial hope for elimi- nation of adhesive disease with the advent of laparoscopy (37) has been replaced by the realization that adhesions do indeed form and reform after laparoscopy, primarily in the operative field, (38, 39) but to a lesser extent than with open surgery. Despite these advantages, bowel obstruction continues to occur frequently in patients following laparoscopic surgery. The mechanism, severity, and risk of obstruction have shifted how- ever. In a report for the French Association for Surgical Research, Duron (39) and colleagues noted that only 33% of postoperative bowel obstructions following various laparoscopic surgeries were due to multiple adhesions, while an additional 17% were due to a single band. Intestinal incarceration (in abdominal wall defect or port site) (See Figures 6.5 and 6.6) was responsible for another 46%. All told, 25% of patients required resection. A report from the Western Pennsylvania Hospital describes unique mechanisms of bowel obstruction, such as internal hernia, are common after laparoscopic bariatric surgery.(40) The reason for this is assumed to be the result of a laparoscopy-related decrease in scar formation between newly apposed peritoneal surfaces which leaves defects open.(41) One can imagine this same phenomenon following laparoscopic colon resection. Obstructions due to inter- nal hernias are associated with a high incidence of bowel threatening ischemia and therefore require a high index of suspicion and prompt surgical management. The authors’ experience is that relaparoscopy, in this patient population, is an excellent technique for diagnosing and managing these obstructions and other complications.(40) General principles to minimize adhesions include gentle han- dling of the tissue, hemostasis, and avoidance of infection and ischemia. Products such as Seprafilm TM (Genzyme), a bioabsorb- able membrane of sodium hyaluronate, and carboxymethylcellu- lose, can be placed at the time of surgery to reduce the incidence of adhesions.(42–44) It should be noted that these products should not be placed adjacent to a fresh anastomosis.(45) A qualification must be maintained in the case of adhesions encountered when operating on a patient with a malignancy. If the adhesions are between a cancer and another structure, they Figure 6.3 Laparoscopic images demonstrating lack of adhesions in a patient undergoing laparoscopic appendectomy for appendicitis 2 years after hand-assisted laparoscopic anterior resection for recurrent sigmoid diverticulitis. (Courtesy of Thomas E. Read, MD, Pittsburgh, PA).  other intraoperative challenges should be treated as an extension of the malignancy. In other words, they should not be divided, but instead resected with the specimen. This process might require partial resection of another structure such as another limb of bowel or abdominal wall. Not all adhesions encountered during surgery for malignancy are malig- nant adhesions however. Attention should be paid to the extent of the tumor such as growth through the full-thickness bowel wall and its relationship to the adhesions as well as the characteristic of the adhesion. lesiOn lOcalizatiOn Up to 22% of endoscopically unresectable colorectal neoplasms with benign histology on initial biopsy harbor invasive adeno- carcinoma. Adhering to oncologically sound principles for these neoplasms is advised.(46) Many of these will not be easily palpable during surgery and even more difficult to localize laparoscopically. For operative planning, particularly when considering a laparo- scopic approach, accurate localization of the tumor is imperative to avoid removal of the wrong segment of intestine.(47) Colonoscopy alone as a localizing technique is inaccurate (48) unless the tumor is clearly noted to be in the direct proximity of to an unmistakable landmark such as the rectum or cecum. As such, localization should be more definitively accomplished preoperatively. Endoscopic injection of India ink in three or four quadrants of bowel adjacent to and distal to, but not through the tumor, is safe and reliable, and preferred in most centers (49, 50) (See Figure 6.7). Other adjuncts for localization include endoscopic placement of clips and subsequent plain film of the abdomen (See Figure 6.8). Alternatively, barium enema or CT colography can be employed. (51) Though more costly than India ink injection and associated with radiation exposure, these modalities offer the additional advantage of preoperative planning for room set up and patient positioning for left vs. transverse vs. right colectomy. One disad- vantage of these approaches is they offer no direct intraoperative evidence of the lesion localization. Therefore they may be most effectively used in conjunction with India ink marking. Some centers have reported success with preoperative endo- scopic clip placement followed by intraoperative laparoscopic Figure 6.4 Laparoscopic images demonstrating lack of adhesions in a patient undergoing laparoscopic appendectomy for appendicitis 2 years after hand-assisted laparoscopic anterior resection for recurrent sigmoid diverticulitis. (Courtesy of Thomas E. Read, MD, Pittsburgh, PA). Figure 6.6 A port site hernia causing a bowel obstruction and injury to the bowel. Figure 6.5 A port site hernia causing a bowel obstruction and injury to the bowel.  improved outcomes in colon and rectal surgery ultrasonography or intraoperative fluoroscopy.(52) These intra- operative imaging modalities, though effective, tend to be cum- bersome, resource intensive, and operator dependent. Due to the flexible nature of the colonoscope, the distance of the tumor from the anal verge cannot be accurately measured on colonoscopy. When the tumor is obviously within the colon or is palpable within the rectum, this limitation of the colonoscope is not an issue. Unfortunately, not uncommonly, a tumor reported to be in the sigmoid colon by colonoscopy is actually much lower and represents rectal cancer. A rigid proctoscope is very useful to accurately measure the distance of the tumor from the anal verge, which not only helps in planning surgery but also determines if the tumor is in a location that its stage might warrant preoperative neoadjuvant therapy.(53) Careful preoperative assessment and planning is the best way to ensure that the appropriate segment of the intestine is removed. The most notable preventable cause includes assumptions made based on colonoscopic determination of a site that is not within the direct proximity to an unmistakable landmark such as the rectum or cecum. Occasionally, however, despite our best efforts, localization attempts fail to identify lesions intraoperatively in up to 12% of cases.(54) Failure to visualize a tattoo can result from disappearance of the tattoo compound, particularly when products other than India ink are used.(55) Additionally, failure to inject the ink compound into the submucosal tissue plane can result in dissemination of the ink and imprecise localization or intraperitoneal injection. Although this presents little direct risk to the patient, it does present a problem with definitive intra- operative localization. Techniques that have been described to minimize this occurrence include injecting saline to develop the submucosal plane before injection of ink.(56) The surgeon must be prepared to deal with the case where local- ization efforts have failed. Blind resection is not advised unless confidently guided by preoperative imaging. Mobilization of the flexures and dissection of the omentum off the transverse colon may reveal a hidden tattoo mark. During laparoscopy, palpation cannot be performed well but a hand assist device can be used to overcome this limitation. Still there are cases where the lesion is too small to palpate and remains unfound. Under such circumstances, intraoperative colonoscopy can permit localization.(57) Use of CO 2 insufflation during the colonoscopy will minimize bowel dis- tention. This is critical if laparoscopic assisted surgery is planned. Requiring equipment, expertise, and time, this is best reserved as a back-up rather than a primary localization modality. Regardless of the technique of localization, opening the specimen after resection to confirm the presence of the lesion is recommended. abdOminal wall clOsure Abdominal wall closure is required following laparotomy and at the specimen retrieval site for laparoscopic colectomy. Wound- related complications such as acute wound failure (dehiscence), infection, and incisional hernia can result in significant morbid- ity. Malnutrition, tobacco abuse, and/or requirement for systemic corticosteroids or chemotherapy will increase risk. Ideally, these factors should be modified preoperatively whenever possible. Intraoperatively, proper technique minimizes the risk of wound complication and will be the focus of this discussion. Acute wound failure, defined as an early separation of the abdominal musculoaponeurotic layers, occurs at an incidence of approximately 1.2% (range 0–2.3%), (58–62) with the majority occurring between the 6th and 9th postoperative days.(63, 64) The most common cause is felt to be suture tearing through the fascia but may also occur as a result of abdominal wall rupture away from the incision or excessive suture interval. Suture break- age and knot slippage are rare.(58, 6, 65–70) An incisional hernia is failure of complete abdominal wall heal- ing following abdominal surgery, resulting in a myofascial defect. The reported incidence of incisional hernias in the literature varies from 9–19%. They often require repair, with recurrence rates as high as 45%, causing further complications. The ideal abdominal wound closure should minimize this complication. Figure 6.8 A plain film of the abdomen after endoscopic placement of clip (arrow) can provide valuable information about the location of the lesion and aid in preoperative planning. Figure 6.7 India ink injected endoscopically before laparoscopy provides excellent lesion localization.  other intraoperative challenges technique Numerous studies have demonstrated mass closure to be superior to layered closure in clinical practice (71–73), since incorporating large bites of tissue reduces the pressure per unit area caused by the suture and decreases the risk of suture cut-through (74, 75). Although a randomized trial of mass versus layered closure showed no significant difference in wound rupture, (76) and most clini- cal studies comparing mass closure to layered abdominal closure have not revealed a difference in the incidence of incisional hernia formation, (73, 77) mass closure of the abdominal wall is currently favored because of its safety, efficacy, and speed. It is important to note that peritoneum heals by regeneration of the layer over the entire defect, and not in incremental advancement from the wound edge.(78, 79) Randomized studies revealed no difference between a one-layered closure (peritoneum not sutured) and a two-layered closure (peritoneum sutured) in midline and paramedian inci- sions.(73, 80) Peritoneal closure is therefore not vital in abdominal closures and may contribute to adhesion formation. Experimental models and cadaveric studies have shown that continuous abdominal wall closure provides the greatest wound security in terms of abdominal dehiscence.(81, 82) Continuous suturing is thought to equalize the tension differences between individual stitches and distributes the tension along the suture line, thus reducing the risk of tissue strangulation and late cut- through.(65, 81, 83, 84) The number of knots and therefore the likelihood of knot slippage may be minimized. A meta-analysis comparing six randomized controlled trials of continuous versus interrupted closure (irrespective of suture type) found the inci- dence of incisional hernias to be significantly less with continuous closure.(85) There is a zone of collagenolysis and matrix degradation that extends out 0.75 cm from each wound edge.(86, 87) Further, fascia strength near its cut edge decreases by 50% during the first 48 hours after an operation.(88) Experimental models have demonstrated a continuous closure while maintaining a 1 cm stitch interval and a 1 cm tissue bite reduces dehiscence rate as compared to smaller tissue bites by minimizing the risk of suture cut-through.(89) suture material Slowly resorbed monofilaments (polydioxanone: PDS ® and polygly- conate: Maxon ® ) are the strongest sutures in the fresh state, followed by the nonresorbable monofilaments (nylon: Ethilon ® and polypro- pylene: Prolene ® ), and then the braided sutures (polyglactin: Vicryl ® , polyglycolic acid: Dexon ® ).(90) Silk and chromic catgut, are not appropriate.(91, 66, 92, 93) With regard to incisional hernia formation, it is known from experimental studies that the abdominal fascia continues to gain strength up to 3 months after surgery.(94) Nylon (Ethilon ® ) loses approximately 20% strength per year while Polypropylene, Surgilene ® , Ethibond ® , Tevdek ® , and polybutester (Novafil ® ) seem to retain their strength indefinitely.(95) Catgut, Dexon ® , and Vicryl ® have tensile strength half-lives in the range of 1–4 weeks, and are not suitable for fascial closure. Vicryl ® , compared with nonresorbable sutures (Prolene ® ), is associated with an increased rate of wound failure and incisional hernias (85). This is in con- tradistinction to more slowly resorbed materials, such as poly- dioxanone (PDS ® ), that do not appear to increase the rate of incisional hernia (85). Multiple randomized trials have failed to demonstrate a difference in dehiscence rates between resorbable and nonresorbable sutures.(58, 96, 97) Additionally, persistent sinus formation and chronic wound infection can be virtually eliminated with the use of resorbable suture.(73, 98) Multiple clinical studies implicate wound sepsis as the most important factor associated with incisional herniation. Multifilament sutures provide a better growth environment for bacteria and are associated with a higher incidence of wound infection compared to monofilament sutures.(77, 99, 100) In summary, a continuous, mass closure using slowly-resorbable monofilament suture with a 1 cm tissue bite and a 1 cm interval is likely the best technique for primary abdominal wall closure.(101) It is assumed that minimizing abdominal wall trauma vis-à-vis laparoscopic approaches may minimize wound related morbidity. retentiOn sutures Retention sutures are thought to aid abdominal closure by prevent- ing wound necrosis and avoiding evisceration. However, problems associated with retention sutures are several and include exacer- bation of the intraabdominal hypertension when the viscera are forcibly contained, and abdominal wall ischemia when the sutures become too tight. Furthermore, several studies have implicated retention sutures in the development of enterocutaneous fistu- lae even when they are placed extraperitoneally. With caution, retention sutures may be considered in abdominal wall closure in the patient with multiple risk factors for delayed wound healing; they are not recommended for those at risk for development of abdominal compartment syndrome. If loss of abdominal domain does not permit a tension free fascial closure, one can consider relaxing incisions to permit medial mobilization of the rectus. This requires dissection above the fascia laterally to the lateral edge of the anterior rectus sheath, which is then incised in the sagittal plane, similar to the technique for separation of parts. This technique should be used cautiously in patients at risk for abdominal compartment syndrome and those at above average risk for wound infection. synthetic prOstheses The use of synthetic mesh has been a popular technique in abdominal wall closures and reconstructions for many years and the most extensive experience is with polypropylene mesh (Prolene ® and Marlex ® ).(102) Multiple reports in the literature cite the advantages of this permanent material, which include availability, ease of use, high tensile strength and durability, maintenance of abdominal wall compliance, potential avoid- ance of future reconstruction, and permeability allowing for peritoneal drainage. However, several investigators have pointed out the many long-term complications related to polypropylene mesh. Most notably, the mesh acts as a nidus of infection and is associated with severe foreign body reactions leading to mesh extrusion and enterocutaneous fistulae with an incidence on the order of 23%.(103) The placement of omentum between the mesh and the viscera has been shown to reduce the early fistula rate to 1–4%.(104) Recently mesh with an adhesion preventative film bonded to it (e.g., Sepramesh ® (Genzyme)) has been intro- duced. The adhesive reductive film may reduce the problem of  improved outcomes in colon and rectal surgery small bowel adherence to the underside of the mesh, which may reduce complications such as enterocutaneous fistulae and allow for an easier re-exploration or mesh removal. Use of polytetrafluoroethylene mesh (PTFE, Gore-Tex ® ) decreases the incidence of fistulization and mesh extrusion. However, PTFE impedes the free egress of abdominal fluid and may contribute to abdominal compartment syndrome and seroma formation. After appropriate consideration, polypropylene, or polytetrafluoroeth- ylene mesh may be considered for abdominal wall reconstruction when there is tissue loss. Resorbable meshes, polyglactin acid (Vicryl ® ) and polyglycolic acid (Dexon ® ), may provide a temporary solution in the man- agement of the difficult abdominal wall. In experimental studies, Dexon ® is 50–70% absorbed and Vicryl ® is almost fully absorbed by 10 weeks. Resorbable mesh offers the early advantages of permanent mesh without the late complications and allows for egress of fluid reducing the chances of intraabdominal hypertension. However, not surprisingly, the reported incidence of hernia is unacceptably high with the use of resorbable synthetic mesh.(105) biOlOgic meshes There are several commercially available meshes (either allografts or xenografts) that are derived from naturally occurring sources of collagen and related connective tissues. The most extensively studied of these is Alloderm (Lifecell) (acellular dermal matrix derived from donated human skin) (106–109) and Permacol (Tissue Science Laboratories) (intact porcine dermal collagen) (110). Other variations on the theme include Collamend (Bard) (cross-linked acellular porcine dermal collagen and its constitu- ent elastin fibers), Allomax ® (Bard) (human dermal collagen), and Strattice ® (Lifecell) (acellular dermal matrix derived from porcine skin). The purported advantage of all of these agents is a low risk of mesh infectious complication in contaminated fields. In the case of acellular dermal matrix, extracellular material provides a sig- nal for fibroblast incorporation, collagen deposition, and matu- ration resulting in tissue that cannot be differentiated from fascia. (111–113) Long-term data are lacking. cOnclusiOns The colorectal surgeon can be faced with any number of potential disasters. 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INTRODUCTION Surgical research over the past three decades has vastly enhanced our technical abilities and knowledge with respect to creating col- orectal anastomoses. The Miles operation, considered state of the art for many years after its description in 1908, has been supplanted by sphincter-saving operations which are now considered the gold standard for the majority of patients with rectal cancer. The era of anal sphincter salvage was ushered in with the commercialization of mechanical staplers that permitted colorectal surgeons to resect can- cers even in the distal rectum and maintain intestinal continuity.(1) In 1979, Heald articulated the concept of total mesorectal exci- sion for rectal cancer resection which was subsequently validated and popularized adding a new dimension to our understanding of curative rectal cancer surgery.(2) In addition, appreciation of the distal mural spread of rectal cancer allowed for closer distal margins without com- promising oncologic adequacy. Concomitantly, chemoradiation was demonstrated to be an effective adjuvant therapy and became part of the armamentarium routinely used to treat patients with rectal cancer. With the ushering in of the era of low, stapled colorectal anastomo- ses, and sphincter preservation, experience was gained diagnosing and treating patients in whom complications of these operations arise. The most common complications related to colorectal anasto- mosis are dehiscence and stricture. The following chapter reviews the relevant surgical literature with emphasis on diagnosis, treat- ment, and prevention of these complications. Less-common complications such as anastomotic cancer recurrence and anas- tomotic hemorrhage and other forms of intestinal anastomoses (ileorectal, ileal pouch anal) will not be reviewed. Leaks and strictures are uncommon events and many of the studies describing these complications present conflicting results, are not definitive, or are statistically under-powered. For a more thorough understanding of the literature, this chapter relies fre- quently on meta-analysis that combines independent clinical tri- als to come to a statistical consensus supporting evidence-based practice. While meta-analysis is not an infallible tool, a well con- ducted meta-analysis can allow for more objective appraisal of the evidence, which may lead to resolution of uncertainty and disagreement and may reduce the probability of false negative results (i.e., lower the rate of a type II error). ANASTOMOTIC DEHISCENCE Anastomotic leak is the most serious complication of colorectal operations as the clinical outcome due to anastomotic disruption can be catastrophic. The risk of death within 30 days of colorectal resection is significantly higher in patients who suffered a leak and mortality has been reported as high as 36% in some series.(3, 4) For patients who survive the acute physiologic trespass of an anas- tomotic leak, there may be formidable, far-reaching implications in terms of long-term survival, quality of life, and function.(5–7) GENERAL CONSIDERATIONS The incidence of anastomotic dehiscence is about 10% for col- orectal anastomoses within 7 cm of the anal verge.(8) The lack of a standardized definition of what actually constitutes a leak makes it difficult to compare series and draw meaningful conclu- sions.(9) Absence of a universal definition and the low frequency of leak events may explain why the surgical literature has so many similarly constructed trials with contradictory results supporting conflicting conclusions with regard to leaks. Common definitions include leaks identified by reoperation for peritonitis, demonstration of extraluminal contrast during an imaging study or observation of colonic contents through a pel- vic drain or through the vagina. When reviewing the literature, it is important to differentiate between patients with clinically rel- evant leaks and asymptomatic patients who have only radiologic evidence of leak as they have different clinical consequences and are treated differently. Due to the potentially devastating consequences of anasto- motic leak, there has been significant research investigating the causes of leaks as well as techniques to reduce the likelihood of anastomotic failure. A number of technical factors considered to contribute to the occurrence of anastomotic leak are subjective assessments made at the time of surgery and are difficult, if not impossible, to quantify objectively. Adequate blood supply to the ends of the bowel to be anas- tomosed is of critical importance. The mesentery and epiploic appendages should be stripped only enough to allow adequate visualization to permit anastomosis. Overzealous cleaning of the bowel compromises the blood supply to the anastomosis and must be avoided. In terms of the blood supply to the colon proximal to the anas- tomosis, preserving the left colic artery by transecting the main sigmoidal artery versus ligating the actual inferior mesenteric artery before the takeoff of the left colic (i.e., a high ligation) is oncologically sound but has not been shown to decrease the risk of leak.(8, 10) Rather than dogmatically coming across a specific named blood vessel, the level of transection along the mesenteric blood supply in a particular operation should be chosen to allow a tension-free anastomosis.(11) In cases where a colostomy is cre- ated for proximal diversion, care should be taken to preserve the 7 postoperative anastomotic complications marginal artery blood supply to the distal colon; this is especially important if the inferior mesenteric artery is transected. Although a variety of methods can be used to assess the blood supply to the anastomosis including Doppler ultrasound and intravenous fluorescein visualized with a Wood’s lamp, in the vast majority of cases, straightforward clinical assessment by inspection and pal- pation is sufficient for this determination. In an effort to improve the blood supply to the rectal side of the anastomosis (and to potentially better protect the hypogastric nerves), it is possible to spare the superior hemorrhoidal artery. Preserving the inferior mesenteric arterial supply to the rectum by transecting the individual sigmoidal branches mid-mesentery may be useful in cases of diverticulitis but would be wholly inap- propriate in cancer cases where mesenteric clearance and lymph node harvest are paramount. While sparing the superior hemor- rhoidal artery, there may be a tendency to avoid dissecting out the proximal presacral space in order to prevent injury to the artery. In operations for diverticulitis, the proximal rectum must be mobilized in order to ensure complete resection of the sigmoid colon and to facilitate passage of the trans-anal circular stapler to the stapled end of the rectum. In theory, sparing the superior hemorrhoidal artery may preserve blood supply to a colorectal anastomosis but data regarding a potential reduction in the leak rate is lacking. Tension across the anastomosis can decrease blood supply and physically disrupt the anastomosis. Care must be taken to suffi- ciently mobilize the bowel to eliminate or minimize any tension at the anastomosis. Technically, this may require division of the inferior mesenteric vein at the level of the pancreas to adequately release the descending colon mesentery to permit the colon to reach to the low pelvis. Similarly, the inferior mesenteric artery may be divided proximal to the takeoff of the left colic artery so that the left colic does not tether the colon up in the abdomen. In addition, splenic flexure release should be performed to afford tension-free reach of the colon to the pelvis when required, as is most commonly the case. Although not mandatory from an oncologic perspective, splenic flexure takedown is only omitted from curative resections when patient anatomy and tumor loca- tion permit.(12) To further reduce the chance of leak, the bowel to be anas- tomosed should be healthy. Inflammation, edema, radiation changes, and thickened bowel wall due to chronic obstruction each influence the risk of leak. Under these suboptimal condi- tions, the bowel should be resected to normal, healthy tissue to allow safe anastomosis; otherwise, a primary anastomosis should be avoided. If unhealthy tissue precludes safe stapled anastomo- sis, then the anastomosis should not be handsewn; tissue unfit for staples is unfit for sutures. When preparing the colon for anastomosis, it is important to note the presence of any diverticula as incorporating a divertic- ulum into the staple line jeopardizes the anastomosis. To avoid this, it is helpful to suture the diverticulum in toward the anvil of the stapler so that the diverticulum ends up in the tissue donuts. Alternatively, the diverticulum can be eliminated by resecting additional colon. When marrying the circular stapler, it is important to pre- vent any extraneous tissue (i.e., vagina, adnexa, bladder, epiploic appendages, etc.) from catching in the stapler. This tissue can interfere with the firing mechanism of the stapler and increases the risk of anastomotic failure. Once the anastomosis is created, air testing with the pelvis under saline should be performed rou- tinely to identify occult defects requiring repair. Once a defect demonstrated by a leak test has been repaired, as evidenced by a negative repeat on-table leak test, the risk of postoperative anas- tomotic leak is not increased.(13) Similarly, in situations where the anastomotic donuts are incomplete but the leak test is nega- tive, the risk of anastomotic leak is not increased.(14) PROXIMAL DIVERSION Many surgeons divert patients undergoing low anterior resection with total mesorectal excision in the hopes of influencing the leak rate and/or the clinical consequences of a leak.(15, 16) Given the low frequency of anastomotic leak, in order to determine whether fecal diversion protects patients from leaking, large, well- designed, multiinstitution trials with homogenous study popula- tions are required. Nonrandomized studies testing the hypothesis that diversion decreases anastomotic failure are inherently biased because of patient selection as surgeons are more likely to divert patients in whom complications are anticipated. The Rectal Cancer Trial On Defunctioning Stoma in Sweden, a large, prospective trial including 234 patients, randomly assigned patients undergoing stapled colorectal anastomosis within 7 cm of the anal verge to have proximal fecal diversion.(17) The clinical leak rate in the diverted and nondiverted groups was 10.3% and 28%, respectively (p < 0.001). In addition, the need for urgent re-operation in the diverted and nondiverted groups was 8.6% and 25.4%, respectively (p < 0.0001). To further evaluate the pos- sible utility of a proximal stoma, a meta-analysis was performed evaluating the role of a defunctioning stoma in low rectal cancer surgery including the Swedish trial and three other smaller ran- domized, controlled trials.(18) The odds ratios for clinical leak and for re-operation due to a leak in diverted patients were 0.32 and 0.27, respectively (p < 0.001). While this meta-analysis and a few other studies demonstrate significant benefits in terms of decreasing the occurrence of leak, much of the remaining litera- ture only supports the concept that proximal diversion amelio- rates the septic consequences of leak but does not influence the actual rate of leak.(14, 19–22) Temporary fecal diversion is not without its own ramifications. It is difficult to predict which individual patients will develop a leak and routine stoma creation will reduce the quality of life in patients in whom no anastomotic complication would have occurred. Moreover, a certain percentage of diverted patients will, inevitably, never have intestinal continuity restored; although, a “temporary” diversion is more likely to become permanent in patients who have experienced a leak.(17, 23) Finally, stoma creation carries its own morbidity rate (i.e., increased wound infection rate at the original operation, stoma complications, morbidity of the reversal operation, etc.) and consumes signifi- cant healthcare resources.(20) Although there is no consensus regarding which patients should undergo proximal fecal diversion at the time of colorectal anasto- mosis, many surgeons routinely consider diversion in the setting of low pelvic anastomoses as these are more likely to leak.(5, 24) . hernia causing a bowel obstruction and injury to the bowel. Figure 6.5 A port site hernia causing a bowel obstruction and injury to the bowel.  improved outcomes in colon and rectal surgery ultrasonography. 51: 438–42.  improved outcomes in colon and rectal surgery 56. Park JW, Sohn DK, Hong CW et al. The usefulness of preop- erative colonoscopic tattooing using a saline test injection method. Layered and mass closure of the abdominal wall. Brit J Surg 1 970 ; 57: 664 7. 75 . DeBruin ThR. Prevention of abdominal disruption and postoperative hernia. Int Surg 1 973 ; 58: 408–11. 76 . Ausobsky