Surgeon Factors

The surgeon is also considered to be an independent variable for the risk of AL, which may be influenced by experience (number of procedures or years of experience) or individual technique/ability. While the role of such individual variations in the technique, decision-making, and ability is difficult and might be confounded by multiple factors, the presence of a learning curve in gaining proficiency in the performance of complex procedures, including IPAA, has been demonstrated. Operating time also influences AL and may be a reflection of a combination of factors including the complexity of the surgery, intraoperative complications, and the need for perioperative resuscitation, surgeon, disease, and patient factors.

Level of the Anastomosis

The location (left colon) and level of the anastomosis (distal) impact blood supply and possibly tension. Compromised perfusion and technical deficiency are major contributing factors for AL. A meta-analysis of 30 studies showed that high inferior mesenteric artery (IMA) ligation in sigmoid or rectal cancer had a higher risk for AL than low ligation of IMA.

Microbiome

Gut microbiotas are also considered to play a major part in AL. While many modalities are used for preoperative colon preparation to reduce bacterial translocation, their role in the prevention of AL is not clear. ^, An initial study from our group demonstrated a significant reduction in AL using a combination of mechanical bowel preparation and oral antibiotics. A meta-analysis including 40 studies of which 28 were randomized with 69,517 patients subsequently confirmed that mechanical bowel preparation along with oral antibiotic decontamination significantly reduced the AL rate as compared with mechanical bowel preparation alone.

Suture and Configuration

Other technical factors including the type of the suture material, anastomotic technique, and configuration of the anastomosis influence anastomotic healing but are also reliant on surgical technique. A systemic review suggests that a single-layer continuous technique using inverting sutures with slowly absorbable monofilament material seems preferable to all suturing techniques to reduce ALs.

Ischemia and Tissue Hypoxia

Tissue ischemia and hypoxia play a key role in the development of anastomotic complications. Intraoperative measurements of serosal oxygen tension with an electrode-based tissue oxygen tension showed that patients with low oxygen tension had a higher frequency of AL than those with high oxygen tension. Some surgeons have used intraoperative oxygen supplements or postoperative oxygen supplements to facilitate colonic anastomosis healing. ^, An intraoperative visual grading system based on bleeding from the marginal vessel was proposed that was shown to predict AL.

The University of California, Irvine Endoscopy Grading Scores were proposed for colorectal anastomosis: grade 1—circumferentially normal mucosa on either side of the colorectal anastomosis; grade 2—mucosal ischemia or congestion less than 30% of the circumference on either side of the colorectal anastomosis; and grade 3—mucosal ischemia or congestion greater than 30% of the circumference on either side of the colorectal anastomosis or any degree of ischemia/congestion on both sides of the anastomosis. ^, A grade 2 anastomosis was associated with a higher AL rate compared to a grade 1 anastomosis (35.7% vs. 7.4%, P < .05) in a case series of 318 patients with colorectal anastomosis for benign or malignant colorectal disorders. However, most surgeons would agree that any concern with an anastomosis intraoperatively necessitates a redo anastomosis, suggesting that an astute surgeon would only accept a grade 1 score.

Hand-Sewn Versus Stapled Techniques

Multiple studies showed that AL is comparable between stapled and hand-sewn anastomosis. However, a recent meta-analysis of six studies of 955 patients with ICA showed that stapled functional end-to-end ileocolic anastomosis is associated with fewer leaks than hand-sewn anastomosis. The expert surgeon judiciously uses both hand-sewn and stapled techniques depending on the individual patient and intraoperative situation based on the location of the anastomosis, access to the area, tissue quality and tension, surgery type, complexity, and duration, to name a few factors.

Configuration of Anastomosis

Configuration or orientation of colorectal anastomosis can be end-to-end ( Fig. 4.1A and B ), end-to-side, side-to-end, and side-to-side (isoperistaltic or antiperistaltic) ( Fig. 4.1C ), which can be achieved with hand-sewn or stapled anastomosis. In a meta-analysis of five studies involving 860 patients with end-to-side anastomosis and 1126 with side-to-side anastomosis, the former group has a lower risk for AL (odds ratio [OR] = 0.185; 95% confidence interval [CI]: 0.054–0.627; P = .007). As with the choice of hand-sewn versus stapled techniques, surgical decision-making depends on the particular circumstance, rather than a rigid approach based on such data, to promote the best outcomes.

Laparoscopic Versus Open Approaches

Various studies have reported comparable AL after laparoscopic versus open hemicolectomy. A laparoscopic approach in obese patients may have a higher risk for AL than open surgery, probably due to anatomy and limitation of the instrument.

Intraluminal Pressure

Intraluminal pressure may be a contributing factor for AL. A meta-analysis showed the placement of a transanal drainage tube reduces the risk of AL after anterior rection for rectal cancer. However, a recent randomized controlled trial of 560 patients with LAR for rectal cancer failed to show that the placement of transanal drainage tubes reduced AL as compared to control (N = 18; 6.4% vs. N = 19; 6.8%, P = .87). There has been concern about luminal air and pressure of salvage endoscopic therapy for AL. A meta-analysis of 16 studies that included salvage stents, over-the-scope endoscopic clips, vacuum therapy, and fibrin glue for AL from colorectal surgery showed that the endoscopic approach may be safe.

Intraoperative Testing of the Integrity of the Anastomosis

Intraoperative ICG fluorescent angiography can effectively assess vascularization of the colic stump and anastomosis in patients undergoing colorectal resection. ^, Its value in reducing AL is, however, controversial. A systematic review and meta-analysis of 23 studies totaling 7115 patients showed that intraoperative documentation of integrity (OR = 0.52, 95%CI: 0.34–0.82, P < .001) and perfusion (OR = 0.40, 95%CI: 0.22–0.752, P < .001) of the lower gastrointestinal tract anastomoses with ICG is associated with significantly lower rate of AL. Intraoperative testing of air leaks may predict the need for reoperation of AL. ^,

Role of Defunctioning Ostomy

While a proximal defunctioning ostomy (loop ileostomy of colostomy) does not reduce AL, it may mitigate the consequences of an AL when this does occur, since it reduces fecal contamination of the site of the leak. Thus, a defunctioning stoma reduces the need for reoperation for severe leaks and might promote healing when AL does occur. However, the creation of a defunctioning ostomy necessitates further surgery for closure and the presence of an ostomy might in itself be associated with various complications.