"Dog ear" formation after double-stapled low anterior resection as a risk factor for anastomotic disruption.

Purpose: The aim of this study was to investigate the possible deleterious effect of the lateral intersecting margins (so-called dog ears) on anastomotic disruption after experimentally performed double-stapled anastomoses.

Methods: Two groups of double-stapled side-to-end anastomoses were performed using pig small intestines. Group A consisted of 35 circular anastomoses and Group B of 32 double-stapled anastomoses with a bilateral dog ear. In both groups bursting pressures were tested using a water-filled, pressure-controlled automatic pumping system (Hamou Endomat), and special attention was paid to the location(s) in the anastomoses were the disruption(s) occurred.

Results: In Group A bursting pressures were significantly higher than in Group B (median pressure, 90 vs. 60 mmHg; P < 0.001, Mann-Whitney U test). Remarkably, in Group B in 13 cases (42 percent) the first disruption occurred at the corner of a dog ear.

Conclusions: We conclude that the lateral intersections of double-stapled anastomoses are a structural weak spot and that the currently most often applied double-stapled anastomosis is a less effective type of anastomosis than a complete circular one. Resolving this technical problem might help to reduce the number of anastomotic disruptions after low anterior resections.