INTRODUCTION — The safety of colorectal surgery, as performed in patients with colorectal cancer and inflammatory bowel disease, has improved dramatically over the last 50 years due to improvements in preoperative preparation, antibiotic prophylaxis, surgical technique, and postoperative management [1]. Nevertheless, complications such as those related to colorectal anastomoses continue to occur. (See "Overview of the management of primary colon cancer" and "Surgical treatment of rectal cancer" and "Surgical management of ulcerative colitis".)
The risks, management, and outcomes of anastomotic complications of colorectal surgery will be reviewed here. These complications include bleeding, dehiscence and leakage, strictures, and fistulas [2]. The risks, management, and outcomes of intra-abdominal, pelvic, and genitourinary complications following colorectal surgery are reviewed elsewhere. (See "Management of intra-abdominal, pelvic, and genitourinary complications of colorectal surgery".)
MORBIDITY AND MORTALITY RISK FACTORS — Colorectal surgery is associated with appreciable morbidity and mortality. Prospective studies, both multicenter and single center, have evaluated patient outcomes after colorectal surgery [3-9]. The rate of major morbidity ranged from 20 to 35 percent [4,7], and the 30 day mortality rate ranged from 2 to 9 percent [4-9]. There does not appear to be a significant difference in 30 day mortality rate between malignant versus benign indications for surgery [4,7,9].
Independent preoperative risk factors that are associated with an increased risk of in-hospital complications include [4,7]:
●Age greater than 70 years
●American Society of Anesthesiologists (ASA) physical status score – Grade III to V
●Emergency surgery
●Neurologic comorbidity
●Cardiorespiratory comorbidity
●Hypoalbuminemia
●Long duration of operative procedure
●Peritoneal contamination
●Rectal excision
Independent preoperative risk factors that are associated with an increased risk of in-hospital and 30 day mortality include [4-9]:
●Emergency surgery
●Loss of greater than 10 percent total body weight
●Neurologic comorbidity
●Age greater than 70 years
●Stage IV cancer (versus earlier-stage cancer)
●ASA physical status score – Grade III to V
●Low surgeon case volume
ANASTOMOTIC COMPLICATIONS — Intestinal anastomotic complications are associated with an increased patient mortality and morbidity, including the potential need for emergency reoperation and prolonged hospitalization. The most common complications include:
●Minor and major bleeding
●Dehiscence and leaks
●Strictures
●Fistulas
Minor bleeding — Minor bleeding is defined as bleeding that does not require blood transfusion and/or intervention (endoscopic, angiographic, or surgical). It usually ceases within 24 hours. Minor anastomotic bleeding after hand-sewn or stapled anastomoses is common but rarely reported. It is usually manifested by the self-limited passage of dark blood with the patient's first few bowel movements. It is estimated that approximately 50 percent of patients who present initially with minor bleeding will progress to major bleeding and require a blood transfusion [10]. There are no high-quality data from prospective studies that have addressed this issue.
It is hypothesized that anastomotic bleeding occurs secondary to inadequate clearance of the mesentery prior to division and/or stapling of the bowel. The risk of bleeding is increased in patients with a bleeding diathesis. Proposed techniques to reduce minor bleeding include [11]:
●Careful inspection of the staple line, especially for side-to-side and functional end-to-end anastomoses.
●Inversion and inspection of the linear staple line prior to closure of the enterotomy through which a stapling instrument was passed has been advocated by some experts.
●Suture ligation, as opposed to electrocauterization, of significantly bleeding points.
●Utilization of the antimesenteric borders of each limb to construct the anastomosis, thereby avoiding inclusion of the mesentery into the staple line.
●Reinforcement of the anastomosis with an absorbable suture is an option used by some surgeons.
Major bleeding — Major bleeding is defined as one or more of the following:
●Hemodynamic instability
●Blood transfusion
●An emergency procedure is warranted (eg, endoscopic, angiographic, surgical)
The reported rate of major bleeding from an anastomosis following colorectal surgery ranges in most studies from 0.5 to 4.2 percent [10,12-14]. Data are limited for ileocolic anastomoses [2]. There is no significant association between the risk of bleeding and the technique of performing the anastomosis (hand-sewn versus stapled colocolic anastomoses) [14]. Specific risk factors for major anastomotic bleeding have not been identified, at least in part due to the small number of reported cases.
Management — The management of patients with anastomotic bleeding should follow the same principles as the management of patients with lower gastrointestinal bleeding from other causes. (See "Approach to acute lower gastrointestinal bleeding in adults" and "Lower gastrointestinal bleeding in children: Causes and diagnostic approach".)
Surgical intervention should be reserved for unstable patients or those who fail conservative measures [13]. We suggest the following approach:
●Initial management should be conservative with supportive care, including blood transfusions and correction of any underlying coagulopathy. Operative management should be considered early for patients with hemodynamic instability despite aggressive resuscitation.
●For persistent bleeding from a low anastomosis, a transanal operative approach is advocated:
•Proctoscopy is performed to evacuate clot.
•Bleeding points are suture ligated.
●For persistent bleeding from higher colorectal or ileocolic anastomoses, initial endoscopic management has been advocated [10,12,13]. However, the number of patients with anastomotic bleeding in each of these studies is small (6 to 17), thereby limiting an assessment of the true success rate. In a series of 1389 colorectal procedures, for example, seven patients (0.5 percent) developed an anastomotic bleed: six were treated endoscopically to control the bleeding, and one required operative management [13]. A potential complication of early postoperative endoscopy is anastomotic dehiscence [10]. Some authors advocate water immersion endoscopy for acute lower gastrointestinal bleeding in the early postoperative period after colorectal anastomoses to limit the risk of colonic leakage [15].
Endoscopic management of bleeding includes [10,12]:
•Isotonic saline washout.
•Electrocoagulation.
•Epinephrine injection.
•Application of hemostatic clips.
For persistent bleeding from higher colorectal or ileocolic anastomoses, angiographic localization and control using intra-arterial vasopressin has been effective [16]. However, theoretically, there is a risk of ischemia and anastomotic dehiscence after angiography [13].
Reoperation with resection of the bleeding anastomosis is necessary when endoscopic management is not successful [13]. There is no consensus regarding what constitutes a failure of endoscopic management in this setting. One may extrapolate from the published literature on the management of lower gastrointestinal bleeding from other causes. (See "Approach to acute lower gastrointestinal bleeding in adults", section on 'Colonoscopy'.)
Outcomes — As indicated by the above observations, data on the management of anastomotic bleeding after colorectal surgery are limited to studies of small numbers of patients. In a literature review of 17 patients with anastomotic bleeding, nonoperative management with endoscopic electrocoagulation or blood transfusion alone was successful in 14 (82 percent of patients) [10]. There are no data from prospective trials addressing issues such as mortality and morbidity.
Dehiscence and leaks
Incidence — The overall incidence of anastomotic dehiscence and subsequent leaks is 2 to 7 percent when performed by experienced surgeons [3,17-19]. The lowest leak rates are found with ileocolic anastomoses (1 to 3 percent), and the highest occur with coloanal anastomosis (10 to 20 percent) [11].
Most anastomotic leaks usually become apparent between five and seven days postoperatively. One study reported that almost one-half of all leaks occur after the patient has been discharged, and up to 12 percent occur after postoperative day 30 [18]. Late leaks often present insidiously with low-grade fever, prolonged ileus, and nonspecific symptoms attributable to other postoperative infectious complications. Small, contained leaks present later in the clinical course and may be difficult to distinguish from postoperative abscesses by radiologic imaging, making the diagnosis uncertain and underreported.
Definition and manifestations — There is no uniform definition of an anastomotic dehiscence and leak [17]. In a review of 97 studies, as an example, 56 different definitions of an anastomotic leak were used [20]. The majority of reports define an anastomotic leak using clinical signs, radiographic findings, and intraoperative findings [21,22].
The clinical signs include:
●Pain
●Fever
●Tachycardia
●Peritonitis
●Feculent drainage
●Purulent drainage
The radiographic signs include (usually computed tomography of the abdomen and pelvis with contrast) [23]:
●Fluid collections
●Gas-containing collections
The intraoperative findings include:
●Gross enteric spillage
●Anastomotic disruption
Risk factors — Risk factors for a dehiscence and leak are classified according to the site of the anastomosis (extraperitoneal or intraperitoneal). A prospective review of 1598 patients undergoing 1639 anastomotic procedures for benign or malignant colorectal disease found a significantly increased risk of anastomotic leak with extraperitoneal compared with intraperitoneal anastomoses (6.6 versus 1.5 percent; 2.4 percent overall) [24].
Extraperitoneal anastomotic leak — Major risk factors for an extraperitoneal anastomotic leak include:
●The distance of the anastomosis from the anal verge – Patients with a low anterior resection and an anastomosis within 5 cm from the anal verge are the highest-risk group for an anastomotic leak [24,25]. In the above-mentioned series of 1639 procedures, the risk of a leak was highest (8 percent) with ultra-low anterior anastomoses [24].
●Anastomotic ischemia – Two prospective studies using laser Doppler flowmetry assessed blood flow to the colon and rectum before and after mobilizing, dividing, and anastomosing the colon [17,26,27]. A decrease in colonic tissue perfusion proximal to the anastomotic site, at the anastomotic site, and at the rectal stump was reported. The magnitude of decrease in blood flow correlated with the subsequent development of an anastomotic leak.
In a meta-analysis of 20 studies, the use of indocyanine green fluorescence angiography was associated with an over 50 percent decrease in anastomotic leaks (3.7 versus 8.6 percent) [28]. The anastomotic sites were altered in almost 10 percent of the patients based on the result of indocyanine green fluorescence angiography.
●Male sex – In a prospective study of 196 patients undergoing rectal cancer resections, multivariate analysis showed a significantly higher rate of anastomotic leak in men with an anastomosis less than 5 cm from the anal verge [21]. It is likely that male sex has the greatest influence on anastomotic leak rates because operating in the narrower male pelvis is technically more challenging. In contrast, male sex does not appear to be a risk factor for intraperitoneal anastomotic leaks [29].
●Obesity – Data are conflicting regarding the role of obesity in anastomotic leak complications. A prospective review of 1417 patients found no association between obesity and the risk of an intraperitoneal anastomotic leak [29]. However, obesity may be a risk factor for an anastomotic leak for low colorectal anastomoses. A retrospective review of 131 patients found that patients with obesity undergoing an anterior resection less than 5 cm from the anal verge had a significantly increased risk of anastomotic leak compared with patients without obesity (33 versus 15 percent) [30].
Intraperitoneal anastomotic leak — Major risk factors for an intraperitoneal anastomotic leak include:
●American Society of Anesthesiologists (ASA) score grade III to V – A retrospective review of 1417 patients found a significantly increased risk of leak with ASA score grade III to V after an intraperitoneal anastomosis compared with those with an ASA score grade I to II (4.6 versus 0.8 percent) [29].
●Emergency surgery – The same retrospective review found a significantly increased risk of leak with emergency surgery after an intraperitoneal anastomosis compared with elective surgery (4.4 versus 1.0 percent) [29]. For patients with both an ASA score grade III to V and an emergency operation, the risk of an anastomotic leak was 8.1 percent.
●Prolonged operative time – A prospective study of 391 elective colorectal resections identified a significantly higher leak rate when the operative procedure was ≥4 hours in duration compared with shorter procedures (5.1 versus 0.5 percent) [25]. More difficult dissections and anastomoses were attributed to the longer operating times and increase in anastomotic leaks.
●Hand-sewn ileocolic anastomosis – In a meta-analysis of six trials with 955 participants with benign and malignant disease, hand-sewn anastomoses were associated with a significantly higher rate of overall anastomotic leaks compared with stapled ileocolic anastomoses (6.0 versus 1.4 percent) [2]. For the subgroup of 825 patients with cancer, hand-sewn anastomoses were also associated with significant risk of an anastomotic leak (6.7 versus 1.3 percent).
In contrast to being a risk factor for extraperitoneal anastomotic leaks as noted in the preceding section, neither male sex nor obesity appears to be a risk factor for intraperitoneal anastomotic leaks [29].
Controversial, inconclusive, or negative — Controversial, inconclusive, or pertinent negative associations between the following variables and an anastomotic leak have been reported:
●Neoadjuvant radiation therapy – Retrospective studies have found a positive, inconclusive, and no association between the use of neoadjuvant radiation therapy and the risk of an anastomotic leak [4,17,30-33]. There are no high-quality data from randomized trials that specifically address neoadjuvant radiation therapy as a risk factor.
●Drains – It is unclear if drains are a risk factor for anastomotic leaks, and the location of the anastomosis may be important. A randomized trial found no increase in anastomotic leaks with drains in patients undergoing elective colonic resection [34], while a large observational study found a significant increase in anastomotic leaks with drains in patients undergoing a low anterior resection for rectal cancer [35].
●Protective stoma – The controversy regarding a protective stoma involves whether or not the stoma prevents a leak and reduces the corresponding clinical consequences. Proximal fecal diversion by a protective stoma (eg, loop ileostomy, loop colostomy, or end ostomy) significantly reduces the overall risk of a reoperation following an anastomotic leak [36].
•In a prospective multicenter study of 2729 patients undergoing a low anterior resection, the overall anastomotic leak rate was similar in patients with and without a stoma (14.5 versus 14.2 percent) [37]. However, patients with a stoma had significantly lower rates of leaks that required surgical intervention (3.6 versus 10.1 percent) and a lower rate of mortality (0.9 versus 2.0 percent).
•A meta-analysis of four randomized trials including 358 patients undergoing a low anterior resection for rectal cancer found that patients with a protective stoma had significantly fewer anastomotic leaks compared with patients who had no protective stoma (9.6 versus 22.8 percent) [38]. Patients with a protective stoma had significantly fewer reoperations for leaks (odds ratio [OR] 0.27, 95% CI 0.17-0.59).
•In a randomized controlled trial of 234 patients undergoing a low anterior resection for rectal cancer that was included in the meta-analysis, the rate of anastomotic leakage with a protective stoma was significantly lower compared with no protective stoma in both men (10.0 versus 29.3 percent) and women (10.9 versus 26.7 percent) [39].
●Hand-sewn colorectal anastomosis – Hand-sewn compared with stapled ileocolic anastomoses are associated with a significant increase in leaks [2]. However, whether this is true for colorectal anastomoses is unclear [14,40].
•A review of nine prospective trials of 1233 patients with a colorectal anastomosis found no significant difference in overall dehiscence and leaks for a stapled anastomosis compared with a hand-sewn anastomosis (13.0 versus 13.4 percent) [14].
•In a prospective, multicenter trial of 732 patients with a colorectal anastomosis, there was an increase in radiographically detected leaks in hand-sewn anastomoses (14.4 versus 5.2 percent) but no difference in clinically detected leak rates [40]. No patient with a radiographic leak without clinical symptoms had an increase in morbidity. There was no difference in morbidity and mortality rates for patients with a hand-sewn or stapled anastomosis.
●Fibrin glue – A retrospective review of 1148 patients with rectal cancer undergoing a sphincter preservation procedure found that use of fibrin glue was an independent predictor of prevention of anastomotic leak (OR 1.94, 95% CI 1.04-3.64). [41]. The anastomotic leak rate in this series was 6.6 percent.
●Laparoscopic procedure – Randomized trials comparing laparoscopic with open colorectal resection for cancer have failed to show any difference in the rate of anastomotic leaks [42,43].
●Mechanical bowel preparation – The role of mechanical bowel preparation (MBP) is controversial. A meta-analysis of 13 prospective trials found no significant difference in overall anastomotic leak rate for patients with an MBP compared to those not having an MBP (4.2 versus 3.4 percent). This conclusion applied to both low anterior resection and intraperitoneal anastomosis.
●Nutrition – Nutritional factors, including hypoalbuminemia, alcohol intake, and weight loss, have shown variable and conflicting results [44,45].
●Perioperative corticosteroids – Data are inconsistent in determining the relationship between perioperative corticosteroid usage and risk of anastomotic leaks [3,25,46-48]. However, a systematic review that included 12 studies demonstrated a significantly higher rate of anastomotic leak for patients who received corticosteroids in the preoperative period compared with those who did not (6.8 versus 3.3 percent) [46].
●Nonsteroidal anti-inflammatory drugs (NSAIDs) – NSAIDs are commonly used for pain control in patients who undergo colorectal surgery. Some data suggest that postoperative use of NSAIDs may increase the risk of anastomotic leak [49-51]. Potential mechanisms include a reduction in prostaglandin-mediated collagen deposition, diminished collagen cross-linking, and increased anastomotic microthrombosis.
In a 2016 meta-analysis of 11 retrospective observational studies (>20,000 patients), NSAID use after colorectal surgery was associated with increased anastomotic leak (OR 1.46, 95% CI 1.14-1.86) [52]. The crude incidence of anastomotic leak was 6.9 percent for patients who received NSAIDs and 5.0 percent for controls. In the same study, NSAID use was not associated with increased anastomotic leak (OR 1.96, 95% CI 0.74-5.16) in the meta-analysis of six randomized trials (473 patients). However, the pooled incidence of anastomotic leak of 5.2 percent for NSAID users versus 2.5 percent for nonusers suggested a trend toward a difference; with only 473 patients and 19 events, the randomized trials were likely underpowered to assess for the risk of anastomotic leaks.
Intravenous ketorolac is a potent NSAID that is commonly used in enhanced recovery pathways for abdominal surgery. In one study of 398,752 patients, 5 percent of patients received ketorolac after colorectal (55 percent) or other gastrointestinal surgery (45 percent) [53]. Ketorolac use was associated with more readmissions for anastomotic complications (OR 1.20, 95% CI 1.06-1.36). In addition, patients who received ketorolac were more likely to require reintervention (OR 1.20, 95% CI 1.08-1.32), emergency department visit (OR 1.44, 95% CI 1.37-1.51), or readmission (OR 1.11, 95% CI 1.05-1.18) within 30 days of surgery. Another study of patients undergoing colorectal surgery, however, failed to find an association between ketorolac use and anastomotic leak [54].
Management — Once an anastomotic leak has been recognized, patients should receive intravenous fluid resuscitation and broad-spectrum antibiotics. Further management is dictated by the clinical scenario and, if patient stability permits, radiologic investigation to localize the leak and determine its severity. Management strategies include observation, bowel rest, percutaneous drainage, colonic stenting, surgical revision, diversion, or drainage [55].
Intraperitoneal anastomotic leak — Management of an intraperitoneal anastomotic leak is dependent upon the patient's clinical condition; the nature of the leak; and, if an exploratory laparotomy is performed, the intraoperative findings. The following treatment options are available, depending upon the clinical stability of the patient, radiographic findings, and feasibility of image-guided percutaneous drainage:
●A subclinical leak, which is defined as a leak detected radiographically in patients with no clinical abdominal findings, can be managed expectantly.
●For patients who present with localized peritonitis and low-grade sepsis, a diagnostic imaging workup is initiated. We perform a computed tomography (CT) scan with oral, intravenous, and rectal contrast. Alternatively, a water-soluble contrast enema may be performed, if available in your institution. If a leak is present, the majority will be localized.
•If a free intraperitoneal leak is demonstrated, the patient should be taken to the operating room for surgical management.
•If the patient is stable with small, contained abscesses (<3 cm), we recommend conservative management with broad-spectrum antibiotics and bowel rest.
•For larger abscesses (>3 cm), multiloculated collections, or multiple collections, an attempt at percutaneous drainage should be made. In those cases where image-guided drainage is not technically feasible or where the patient's clinical condition deteriorates despite drainage, surgical intervention in the form of an exploratory laparotomy should be undertaken as described in the following paragraph.
●Patients who present with generalized peritonitis or high-grade sepsis with hypotension should be resuscitated and brought to the operating room for an exploratory laparotomy on an emergency basis. Surgical management is dependent upon the intraoperative findings.
•If an inoperable phlegmon is encountered, the safest approach is to place para-anastomotic drains and perform proximal temporary fecal diversion with either a loop ileostomy or colostomy.
●For patients who have a major anastomotic defect (generally defined as >1 cm or greater than one-third the circumference of the anastomosis) [55], the options include resection of the anastomosis with creation of an end stoma with/without mucus fistula, resection of the anastomosis with re-anastomosis and proximal diversion, or, rarely, exteriorization of both ends of the stoma.
•In selected patients in whom the defect is minor and the tissue quality is adequate, one may consider primary repair of the anastomosis with drain placement and proximal diversion.
Extraperitoneal anastomotic leak — In most cases, management of an extraperitoneal anastomotic leak is similar to that of an intraperitoneal leak. The following treatment options are available, depending upon the clinical stability of the patient, radiographic findings, and feasibility of image-guided percutaneous drainage:
●For patients with generalized peritonitis and high-grade sepsis, emergency operative management should be performed, as described in the previous section.
●Management of patients with a pelvic abscess depends upon the patient's clinical condition, location of the abscess, and whether the abscess is in continuity with a leak. Consideration of proximal diversion is warranted in symptomatic patients. Determination of whether the abscess is contained or is in continuity with the leak can be made by performing a water-soluble contrast enema.
•Patients with a contained abscess should be placed on intravenous antibiotics and undergo abscess drainage if the collection is larger than 3 cm. CT-guided drainage via a transabdominal, transvaginal, transanal, or transrectal route should be performed if technically feasible. Rarely, a trans-sciatic or transgluteal approach may be necessary.
•For very low pelvic abscesses that are in continuity with the anastomotic leak and that may be anatomically inaccessible by image-guided techniques, we perform an examination under anesthesia with transrectal or transanastomotic drainage. This approach is facilitated by making a wide opening in the anastomosis and/or inserting a mushroom-tipped catheter into the abscess cavity.
Outcomes — Anastomotic dehiscence and leaks are associated with an increased risk of mortality compared with patients without a leak (15.8 versus 2.5 percent) [3] as well as a prolonged hospital stay, an increased rate of mortality, and an increase in cancer recurrence rates [29,40,56]. A retrospective review of 1417 patients with an intraperitoneal anastomosis found a significantly longer length of hospital stay for patients with a leak compared with those without a leak (28 versus 10 days) as well as a significantly higher in-hospital mortality rate (32 versus 4 percent) [29].
Local recurrence — An anastomotic leak is associated with an increased risk for local recurrence for rectal and colon cancer. The following observations illustrate the range of findings:
●A meta-analysis of 11 prospective and retrospective studies that included 9896 patients with rectal cancer found a significantly increased risk of local recurrence with an anastomotic leak compared with patients with no leak (OR 1.60, 95% CI 1.33-1.92) [57].
●A prospective study of 1722 patients undergoing colorectal cancer resection found a significantly higher five-year mortality rate in patients with a leak compared with those without a leak (56 versus 36 percent) [56].
●In a prospective study of 306 patients with resectable colon cancer, patients with an anastomotic leak had, at 48 month follow-up, significantly higher rates of both tumor recurrence (45 versus 30 percent) and cancer-specific mortality (53 versus 31 percent) compared with patients without an anastomotic leak [40].
●In contrast, a meta-analysis of three prospective studies that included 1990 patients with colon cancer only found a nonsignificant increased risk of local recurrence with an anastomotic leak compared with patients with no leak (8.8 versus 6.6 percent, OR 2.16, 95% CI 0.88-5.29) [57].
Chronic presacral sinus — A chronic presacral sinus is an infrequent complication of a posterior leak in a coloanal or ileal pouch-anal anastomosis. A retrospective review of 100 consecutive cases of total mesorectal excision with proximal diverting ileostomy identified a para-anastomotic sinus in eight patients [58]. Spontaneous closure occurred in three patients, and late malignant transformation developed in two.
Strictures — The incidence of an anastomotic stricture or stenosis after a colorectal anastomosis ranges from 0 to 30 percent [59-61]. This wide range is due at least in part to an imprecise definition of stricture. Studies have defined anastomotic stricture in terms of the inability to pass a proctoscope (12 mm diameter) [62,63] or a larger rigid sigmoidoscope (19 mm diameter) [61] through the stenosis. A clinically significant stricture typically presents with signs of a partial or complete bowel obstruction. The incidence of symptomatic strictures ranges from 4 to 10 percent [33,61,64].
Most patients with an anastomotic stricture do not require an intervention. This issue was addressed in a prospective study of 179 consecutive patients with a stapled colorectal anastomosis in whom a benign stenosis or inability to pass a rigid proctosigmoidoscope occurred in 20 percent [61]. Only eight patients (4 percent of all patients and 22 percent of those with a stenosis) presented with obstructive symptoms attributable to the stenosis; all eight were treated by endoscopic dilatation alone.
Risk factors — An anastomotic stricture may be the result of tissue ischemia, inflammation, radiation, anastomotic leak, or recurrent disease [65]. The literature supporting the role of the above factors in the pathophysiology of anastomotic strictures is sparse. Both randomized trials and prospective observational studies have identified the following risk factors for stricture formation:
●A stapled colorectal anastomosis, but not a stapled ileocolic anastomosis, is associated with an increased risk of stricture formation compared with a hand-sewn anastomosis. A systematic review of seven randomized trials with 1042 patients with a colorectal anastomosis found a significantly higher rate of stricture formation with stapled anastomosis (8 versus 2 percent) [14]. In contrast, a meta-analysis of six trials with 955 patients with an ileocolic anastomosis found no difference in the rate of stricture between the two types of anastomosis [2].
●In a prospective observational study, the risk of developing a stenosis following a colorectal anastomosis was 2.4 times greater in men compared with women (25 versus 14 percent) [61]. This may reflect the anatomically narrow male pelvis and the associated increased technical difficulty.
Management — Management of an anastomotic stricture depends upon its etiology and anatomic location.
Malignant strictures — When the initial resection is performed for malignancy, it is imperative to rule out local recurrence. The evaluation includes laboratory tests (carcinoembryonic [CEA]), radiographic imaging (CT scan, magnetic resonance imaging [MRI], endoscopic ultrasound, or positron emission tomography [PET] scan), and endoscopic biopsy of the stricture.
Malignant recurrence is reported to be rare in early strictures (up to six months), but the risk of local malignant recurrence increases with time [59]. In the absence of distant metastatic disease, surgical resection of a malignant anastomotic stricture should be performed, with restoration of gastrointestinal continuity if technically feasible. In the presence of distant metastatic disease or unresectable locoregional disease, proximal fecal diversion may be warranted for palliation.
A retrospective review of 68 patients undergoing a colorectal resection for malignant disease found that tumor recurrence was responsible for seven (10 percent) anastomotic strictures [63]. The initial management was endoscopic dilatation for all 68 patients, with a success rate of 59 percent (40 patients). For all seven patients with a stenosis secondary to recurrent tumor, the initial biopsy was negative for malignancy. Persistence or recurrence of stenosis following endoscopic dilatation led to a subsequent biopsy and the diagnosis of malignancy. Four of the seven patients were treated by a surgical resection, and the other three received a palliative colostomy.
Benign strictures — Benign low colorectal, coloanal, and ileoanal strictures are usually effectively treated with repeated dilatation using an examining finger or rubber dilators. Higher colorectal, colocolic, or ileocolic strictures may be managed endoscopically. Endoscopic balloon dilatation is successful in 88 to 100 percent of benign cases [61,63,66]. Endoscopic alternatives employing the use of self-expanding metallic stents or endoscopic transanal resection of strictures are effective in treating severe anastomotic strictures [67]. In refractory cases, surgical revision may be required, and, occasionally, permanent fecal diversion is warranted.
Outcomes — Endoscopic dilatation is more successful and carries a lower complication rate in patients who were operated upon for benign rather than malignant disease.
●In a retrospective review of 94 patients, endoscopic dilatation was significantly more effective with a benign stricture compared with a malignant stricture (88 versus 59 percent) [63]. The complication rate was significantly higher in patients who had previous surgery for cancer (23 versus 4 percent). Complications of endoscopic dilatation included benign restenosis (11 percent), perforation (5 percent), and abscess formation (2 percent).
●A retrospective study of 27 patients with colorectal anastomotic strictures refractory to endoscopic management underwent surgical revision with either a colorectal or coloanal anastomosis without a mortality and no evidence of restenosis in any patient at a median follow-up of 28 months [59]
Fistulas — The risk of a fistula occurring after a colorectal, coloanal, or an ileocolic anastomosis ranges between 1 to 10 percent [31,68-73]. Rectourinary (rectovesical, rectourethral) fistulas following colorectal surgery are rare [74,75]. Data are limited on the frequency with which rectourinary fistulas are malignant. In the largest series of patients with an acquired rectourinary fistula, only 3 of 15 fistulas were related to rectal cancer [74].
Fistulas can develop between the anastomosis and the skin, vagina, genitourinary system, and presacral space. Enterocutaneous (colocutaneous) fistulas that develop between the colorectal anastomosis and the skin are usually a late manifestation of an unrecognized anastomotic leak. (See "Rectovaginal and anovaginal fistulas" and "Enterocutaneous and enteroatmospheric fistulas".)
Risk factors — Risk factors for the development of a fistula include an anastomotic dehiscence and leak, an anastomosis ≤5 cm from the anal verge, preoperative radiation therapy, advanced cancer, resection for cancer, abscess, double stapled anastomosis, and inadvertent inclusion of the vaginal wall in a stapled anastomosis [31,69,70,76,77].
The following findings have been noted in different studies:
●In a retrospective review of three cohorts totalling 390 women undergoing a low anterior resection for rectal cancer, 20 (5.1 percent) developed a symptomatic anastomotic vaginal fistula (AVF) and 32 (8.2 percent) developed a conventional anastomotic leak [31]. The AVF was diagnosed clinically as an evident communication between the vagina and the anastomosis.
•Compared with women who did not develop an AVF or conventional anastomotic leak, women with an AVF were significantly more likely to have an anastomosis ≤5 cm from the anal verge (65 versus 19 percent), have received preoperative radiation therapy (85 versus 38 percent), and have Union for International Cancer Control (UICC) cancer stage IV (30 versus 8 percent).
•Compared with women who did develop a conventional anastomotic leak, women with an AVF were significantly more likely to have an anastomosis ≤5 cm from the anal verge (4.3 versus 5.0 percent), a lower body mass index (22 versus 25 kg/m2), and a diagnosis after hospital discharge (70 versus 41 percent). An AVF presented later than a conventional leak (25 versus 11 days).
•Intraoperative vaginal perforation, salpingo-oophorectomy, concomitant hysterectomy, and a previous hysterectomy were not associated with the formation of an AVF or a conventional leak.
●A questionnaire sent to members of the American Society of Colon and Rectal Surgeons regarding the incidence and treatment of rectovaginal fistulas (RVFs) following a low anterior resection (LAR) or an abdominal perineal resection (APR) reported on results of approximately 6300 LAR and 2100 APR procedures [69]. Fifty-seven patients developed an RVF. The hypothesized causes of the RVF included inadvertently including the vaginal wall with a stapled anastomosis, spontaneous drainage of a pelvic abscess, or recurrent tumor. Fifty-four fistulas were clinically evident, 53 occurred in a stapled anastomosis, and 48 were directly adjacent to the anastomotic site on clinical examination.
●In a retrospective review of 161 patients undergoing an LAR for a primary rectal cancer, 16 (10 percent) developed an RVF [70]. The risk of an RVF was greatest for patients treated with an intersphincteric resection (49 percent), a very low LAR (18 percent), LAR (7 percent), and those with a double stapled anastomosis compared with a single stapled anastomosis (15 versus 5 percent). No patient treated with a high anterior resection procedure developed an RVF.
Management — Fistulas are best managed by addressing the sites that are involved. Options include conservative management, diverting colostomy, or endoanal or endovaginal advancement flap reconstruction [70]. There are no high-quality data available from prospective trials.
●Rectovaginal and colovaginal fistulas – Spontaneous closure is unlikely for patients with colovaginal or rectovaginal fistulas, and proximal fecal diversion may be necessary to alleviate symptoms. The optimal time for surgical excision and repair of the fistula is controversial. High anastomotic vaginal fistulas may require a colorectal resection, while low fistulas may be amenable to transvaginal or transanal excision and repair [71]. (See "Rectovaginal and anovaginal fistulas", section on 'Surgical principles'.)
●Colocutaneous fistulas – Conservative and supportive management is the initial approach for patients with a colocutaneous fistula, since approximately one-half will close spontaneously at a mean of 30 days (range 10 to 180 days) [78]. If the fistula persists longer than six weeks or is a high-output fistula, it is less likely to close spontaneously. Definitive operative intervention should be delayed for approximately three to six months to allow for resolution of sepsis and/or to restore nutritional status. The management of enteric fistulas, including local control and nutritional support, is discussed elsewhere. (See "Enterocutaneous and enteroatmospheric fistulas".)
●Rectourinary fistulas – Data are limited on the management of rectourinary fistulas. In a series of five patients with a rectourinary fistula related to a rectal cancer, surgical management included excision and repair or reconstruction in three, a permanent colostomy and a permanent urinary diversion in one, and a permanent colostomy with temporary urinary diversion in one [75]. All patients experienced relief of symptoms. The optimal surgical management of a rectourinary fistula for patients with locally curative disease is an excision and with reconstructive procedures. For patients with advanced or unresectable disease, a permanent fecal and/or urinary diversion procedure is necessary.
Outcomes — Morbidity and mortality with fistulas varies with the location of the fistula.
●Rectovaginal fistulas – Outcomes related to the management of RVFs following colorectal surgery are difficult to quantitate because of the small number of reported cases. The following findings are illustrative:
•A retrospective review included 16 patients with RVFs following LAR for rectal cancer [70]. Spontaneous closure of the fistula occurred in six patients, reconstructive surgery by various methods resulted in complete healing in eight patients, and death due to metastatic disease occurred in two patients.
•In a series of nine patients with RVFs following colorectal surgery, four required permanent fecal diversion to manage their fistula [71].
●Colocutaneous fistulas – Colocutaneous fistulas are generally low-output fistulas and have an almost 50 percent chance of spontaneously closing. In contrast, high-output fistulas are associated with mortality rates between 5 to 20 percent [78,79], and fistulas that do not spontaneously close are associated with a high morbidity rate [79].
●A retrospective review of 61 patients referred to a specialized center reported the complication and mortality rates following surgical repair of an enterocutaneous fistula with an open abdominal wound [79]. Initial management included treatment of sepsis and restoration of nutritional status, which was then followed by an operative resection of the fistula and closure of the abdominal wound. There were 3 postoperative deaths, 7 recurrent fistulas, and 52 patients with postoperative respiratory and surgical site infections. Recurrent fistulas occurred only in the patients with reconstruction of the abdominal wall with prosthetic mesh compared with suture closure (7 of 29 versus 0 of 34 patients).
●Rectourinary fistulas – There are few reported cases of a rectourinary fistula [75] and no high-quality data from prospective trials or large retrospective reviews reporting outcomes following a colorectal resection.
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Colorectal cancer" and "Society guideline links: Colorectal surgery for cancer".)
SUMMARY AND RECOMMENDATIONS — The safety of colorectal surgery, as performed in patients with colorectal cancer and inflammatory bowel disease, has improved dramatically over the years due to improvements in preoperative preparation, antibiotic prophylaxis, surgical technique, and postoperative management. Anastomotic complications following colorectal surgery include bleeding, dehiscence and leakage, strictures, and fistulas.
●For management of major anastomotic bleeding, the initial management should be conservative with supportive care, including blood transfusions and correction of any underlying coagulopathy. Endoscopic and/or surgical intervention should be reserved for unstable patients or those with persistent bleeding despite conservative measures. (See 'Major bleeding' above.)
●The management of an extraperitoneal dehiscence includes percutaneous drainage for a low pelvic abscess that is in continuity with anastomotic leak. For patients with a low pelvic abscess in continuity with the anastomotic leak that is not amenable to percutaneous drainage, an examination under anesthesia with transrectal or transanastomotic drainage should be performed. Consideration of proximal fecal diversion is warranted in symptomatic patients. (See 'Extraperitoneal anastomotic leak' above.)
●Options for management of an intraperitoneal dehiscence include conservative management with broad-spectrum antibiotics and bowel rest, image-guided percutaneous drainage of abscesses, temporary fecal diversion and/or drainage, or resection of the anastomosis. Early operative intervention is warranted for patients with generalized peritonitis and sepsis or patients with a free intraperitoneal leak on radiographic imaging. (See 'Intraperitoneal anastomotic leak' above.)
●The initial management for anastomotic strictures includes finger dilatation for low anastomoses and endoscopic balloon dilatation for higher anastomosis. It is imperative to rule out local recurrence if the initial resection was performed for malignancy. In refractory cases, surgical revision may be required, and, occasionally, permanent fecal diversion is warranted. (See 'Strictures' above.)
●Colocutaneous fistulas can be managed conservatively as most will close without operative intervention. (See 'Fistulas' above.)
●Anastomotic vaginal fistulas should be managed initially by proximal fecal diversion. Definitive surgical repair should follow. (See 'Fistulas' above.)
ACKNOWLEDGMENT — The UpToDate editorial staff acknowledges Lara J Williams, MD, MSc, FRCSC, who contributed to an earlier version of this topic review.
