Introduction
Although significant improvements in oncologic outcomes after surgery for colorectal cancer have been achieved, the issue of anastomotic leaks remains a challenge. In fact, an anastomotic leak is one of the most serious complications of any restorative colon or rectal resection. Leaks account for a quarter of all postoperative deaths after colorectal surgery and up to one third of all deaths after low anterior resection. In addition to mortality, anastomotic leaks are associated with increased morbidity and decreased quality of life because of the rate of permanent ostomy (up to 72%), the need for additional surgeries, and the functional consequences of the related sepsis. In the literature, the major focus has been on the causes of anastomotic leaks, with little attention given to their management. The mortality rate has not changed in the past three decades despite significant improvements in critical care, and our knowledge of factors contributing to leaks unfortunately has not resulted in effective leak prevention. Anastomotic leaks traditionally have been thought to be due to problems with technique, yet the rate of leaks has remained unchanged despite the introduction of the surgical stapler. If leaks were the result of technical error, surgeons would be the best predictors of these events. However, studies have shown that a surgeon’s own judgment in predicting the risk of a leak is very poor. Given that anastomotic leaks remain both inevitable and unpredictable, the only way that postoperative outcomes can be improved is through early detection and better management when they do occur.
What Defines a Leak?
Despite the constant rate of anastomotic leaks, little consensus exists among surgeons about how to manage the problem. Much of this lack of consensus could be due to variation in how an anastomotic leak is defined. The definition of an anastomotic leak used in this chapter will be consistent with the definition put forth by the International Study Group of Rectal Cancer. An anastomotic leak is defined as a defect of the intestinal wall at the anastomotic site leading to a communication between the intra- and extraluminal compartments. This communication can be confirmed radiographically, endoscopically, or intraoperatively. Anastomotic leaks can be symptomatic (clinical) or asymptomatic (subclinical). Clinical leaks generally cause symptoms of pelvic discomfort and signs of sepsis and can be identified endoscopically or with imaging. Subclinical leaks may only be identified at a follow-up endoscopy, prior to stoma closure, or during surveillance for cancer risk.
Principles of Management
The goals of any leak management strategy should be preservation of the anastomosis, minimal morbidity and mortality, and maintenance of quality of life. These goals can best be achieved through early diagnosis, control of sepsis, and use of interventions that do not increase the risk of a permanent stoma.
Early Diagnosis
Mortality rates have been shown to increase from 0 to 18% if an anastomotic leak is recognized after the fifth postoperative day. A delay of 2½ days in definitive intervention for a recognized leak increased the mortality by 15%. A leak that is present from the time of the operation is difficult to diagnose early in the postoperative period because signs and symptoms take time to appear, especially if a diverting ostomy is present or the patient has a prolonged ileus. Symptomatic leaks are typically diagnosed between 7 and 12 days after surgery. Asymptomatic leaks can be diagnosed months later, especially if the leak is through a portion of the anastomosis that is not in the direct fecal stream (e.g., the blind end of a side-to-end anastomosis). Overall, up to 42% of leaks are diagnosed after the patient is discharged. An anastomotic leak can cause a variety of nonspecific cardiovascular, pulmonary, and gastrointestinal (GI) symptoms. Signs and symptoms, such as fever and leukocytosis, are usually indicative of a postoperative infectious complication and rarely reach predictive values while the patient is still in the hospital. Peritonitis is unlikely in patients if their anastomosis is either extraperitoneal or covered by a proximal stoma. Drains placed at surgery can provide early clues to the presence of a leak but can just as easily be misleading. Goligher examined data from a large series of patients, all of whom underwent a postoperative contrast enema after undergoing colorectal anastomoses, and found a 30% leak rate. The study was performed prior to the introduction of stapling techniques but still serves to encourage a high index of suspicion for a leak after a colorectal anastomosis.
Imaging
Computerized tomography (CT), CT with rectal contrast material (CT-RC), and a gentle water-soluble contrast enema (WSCE) are the preferred techniques for diagnosing a leak but can fail to diagnose it at the vital early stage. CT-RC has proved to be more sensitive in identifying anastomotic leaks than WSCE and also permits accurate identification of any abscess that may be amenable to percutaneous drainage. Contrast material can be injected down the distal limb of the ostomy to prevent further disunion of the anastomosis by injection through the rectum.
CRP Levels
C-reactive protein (CRP) appears to be a very promising marker for anastomotic leaks. CRP levels remain elevated beyond the third day postoperatively in all patients who have had leaks. We have noticed that the absolute value is less important than the trend. Postoperative CRP levels increase on postoperative days 1 and 2 but begin to decrease on postoperative day 3 and onward in the vast majority of patients who do not have a leak. If CRP levels are not declining by postoperative day 4 or 5, further investigation may be warranted. However, there is no level 1 evidence to prove that postoperative serum CRP levels accurately diagnose a leak. They are another piece of evidence that guides the clinician and adds minimal cost to the care of the patient.
Endoscopy
Endoscopy has primarily been used to assess a radiographically diagnosed colorectal anastomotic leak in the acute setting or prior to takedown of a diverting ostomy. When used in conjunction with CT-RC, endoscopy can provide additional information about the anastomosis that is important for the subsequent management of the leak. This information includes:
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The presence of ischemia or necrosis
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Exudate or other debris unlikely to adequately drain using percutaneous methods
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Disproving a false-positive WSCE study (a false-positive rate of up to 6.4% occurs in the setting of a side-to-end anastomosis)
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Evaluation of a suspected leak in more proximal anastomoses, which are known to be less adequately evaluated by contrast studies
Endoscopy has been proposed as a primary diagnostic tool to be used routinely for the evaluation of the esophagogastric anastomosis after esophageal resection. Patients without signs of a leak who underwent routine endoscopy were found to have either ischemia or a leak. Routine endoscopy did not cause an anastomotic complication or further worsening of the existing dehiscence. A normal anastomosis on endoscopy was a reliable negative predictor for absence of a leak. No colorectal studies have evaluated the safety and efficacy of routine endoscopy in diagnosing an anastomotic leak, and thus endoscopy should only be used to confirm a questionable leak seen on imaging.
Leaks from proximal colonic anastomoses can present with more significant symptoms than those from a colorectal or coloanal anastomosis, including peritonitis, profound sepsis, or septic shock. In such patients, a repeat exploration is mandatory, and the leak can be confirmed by either direct examination or intraoperative endoscopy. A stable patient should have a CT scan with oral contrast material to decide whether the diagnosis of an anastomotic leak should be further pursued. It is possible for a proximal leak to be walled off by the omentum or loops of intestine, with the possibility of an associated collection that is amenable to percutaneous drainage and bowel rest.
Variables Directing Management
Location: Intraperitoneal versus Extraperitoneal
Patients with anastomotic leaks within the peritoneal cavity more often present with sepsis from diffuse contamination and peritonitis than do patients whose leaks are extraperitoneal, which is the likely explanation for higher leak-related mortality associated with right-sided colon resections. Leaking intraperitoneal anastomoses should be resected and reconstructed (if possible) with diversion if contamination is severe or the interval from identification of the leak to a repeat operation is prolonged. If intestinal ischemia and an uncertain blood supply are present, a separated ostomy and mucus fistula is constructed.
Patients with distal extraperitoneal leaks may already have undergone diversion and rarely benefit from a laparotomy. Fecal diversion may be necessary if it has not already been performed. Revision of the low pelvic anastomosis should only be attempted if the defect can be seen and the risk of further disruption of the suture line is small.
Any established perianastomotic abscess (intraperitoneal or extraperitoneal) should be evaluated to rule out an anastomotic leak by searching for a connection to the anastomosis. A contained intraperitoneal perianastomotic abscess can undergo successful percutaneous drainage. Any resulting enterocutaneous fistula can be managed conservatively with bowel rest or diversion as needed.
Type of Anastomosis: Ileocolic versus Colorectal/Ileorectal
An uncontained leak from a colorectal anastomosis can be managed by abdominal washout and proximal diversion. This management has been shown to effectively control the sepsis after a resection for diverticulitis. Resection of the failed anastomosis and creation of an end ostomy is associated with increased morbidity and a higher risk of a permanent stoma. Repair of the anastomosis should only be attempted if the suture line will not be compromised. The risk of a leak after a colorectal anastomosis increases if the site of the anastomosis is lower in the rectum (10% to 17%).
Leakage after an ileocolic or proximal colon anastomosis occurs infrequently (at a rate of 2% to 3%). Resection and reanastomosis for ileocolic, colocolic, and small bowel anastomosis are as safe as diversion alone in patients undergoing staged laparotomies for secondary peritonitis. Therefore, in the case of an ileocolic anastomosis, it might be best to perform a resection and reanastomosis. The decision to divert will be influenced by the degree of contamination and the blood supply of the bowel of the anastomosis. In turn, the degree of contamination depends on the time from the leak to laparotomy. An additional factor in the decision about whether to resect and reanastomose with a diverting loop, or to resect and exteriorize, is that operations to close an end stoma typically require a midline incision with lysis of adhesions and carry increased morbidity (leak and mortality) compared with a loop ileostomy takedown through a local incision.
A large anastomotic dehiscence or significant necrosis at an ileocolic anastomosis in an unstable patient with a shortened inflamed mesentery (as a result of Crohn disease) and/or a large body habitus is an absolute indication for an end ileostomy and mucus fistula. Resection, repeat anastomosis, and loop ileostomy creation puts the patient at risk for another leak, and thus resection and creation of an end ileostomy and mucus fistula is a better choice.
Symptoms: Sepsis versus Symptomatic versus Asymptomatic
Signs of sepsis and septic shock mandate an immediate operation to control the infectious source because as time passes, mortality increases. Secondary peritonitis is associated with high mortality (20% to 60%).
The three key components to controlling the source of infection include (1) eradicating the source, (2) thorough drainage, and (3) preventing recurrent sepsis.
Early control of sepsis prevents multiorgan failure, and a quick but definitive operation is the goal. Laparotomy and washout should be the standard. Laparoscopic washout, especially if the previous operation was performed laparoscopically, can be considered, and diversion alone can effectively control the source of infection in a proximal anastomosis. Septic shock is an indication for anastomotic resection with creation of an end ileostomy and mucus fistula. In addition, if a column of stool is present above the leaking anastomosis, the anastomosis should be taken down and an end colostomy made to resolve the septic shock.
Abbreviated laparotomies with either a staged damage-control repeat laparotomy or maintenance of an open abdomen should only be considered if the source of sepsis cannot be controlled at the index operation. Patients effectively treated with closed abdomens at the first operation do far better than when either a repeat laparotomy is planned or the abdomen is left open. On-demand laparotomy is the preferred approach. If a significant improvement in overall status has not occurred within 48 hours, a repeat laparotomy is indicated. Mortality has been shown to increase by 50% if a repeat laparotomy is undertaken more than 48 hours after the initial laparotomy.
Asymptomatic leaks found on imaging have been considered benign, and treatment is not needed. Unfortunately, all leaks, with or without symptoms, are associated with perianastomotic inflammation and fibrosis. Despite this traditional view of asymptomatic leaks, recent research has shown that patients with subclinical leaks from a colorectal or coloanal anastomosis have higher incontinence scores, poorer bowel function, and an increased number of surgical or endoscopic procedures, costing up to $3080 per patient. Early diagnosis allows local drainage of extrarectal collection or placement of an Endo-SPONGE (B Braun Melsungen AG, Melsungen, Germany) to prevent the onset of fibrosis. Defects become less amenable to closure and rectal dysfunction becomes permanent as time progresses.
Previously Diverted: Proximal Diverting Ostomy versus Nondiverted
Diverted leaks at extraperitoneal anastomoses are less likely to be associated with poor function than are nondiverted anastomoses. Proximal diversion (either at the initial surgery or after a leak) improves healing and future function by allowing for easier and more effective use of endoscopic treatments of the leak. Continued passage of stool through the leaked anastomosis results in chronic inflammation, with severe pelvic fibrosis, decreased rectal compliance, and poor anal function. Although proximal diversion at the time of colorectal anastomosis may not prevent leakage, it certainly changes the impact of an anastomotic leak.
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