Introduction: Colorectal anastomotic leak, a feared complication, results in significantly increased patient morbidity, mortality, and hospital resource utilization. The overall incidence of colorectal anastomotic leak is approximately 11% with increasing rate the closer the anastomosis is to the anal verge. Because surgeons are unable to reliably predict which anastomosis would fail, most will construct a diverting ileostomy for low colorectal anastomosis to circumvent the devastating complications of anastomotic failure. Despite extensive investigations on technical considerations of anastomosis construction, anastomotic leaks continue to occur at an unacceptably high rate.
Discussion: In this review, we examine the major known risk factors and technical considerations that have been implicated as factors in leakage. Although surgical technique has evolved over the past several decades with the advent of newer surgical staplers, laparoscopy, and robotics, we have not witnessed a decrease in the incidence of colorectal anastomotic leaks suggesting that the fundamental pathogenesis of anastomotic leak remains unknown. Among the factors contributing to anastomotic healing, intestinal bacteria remains largely overlooked even though compelling evidence exist that intraluminal microbes could play a major role in pathogenesis of anastomotic leak. Further investigation focusing on intestinal microbes could be one such avenue for uncovering the elusive cause of colorectal anastomotic leak.