Experimental Study of Mechanical Integrity Testing in Stapled Large Bowel: Methylene Blue Leak Test Is Not Inferior to Air Leak Test

Background/Objectives: Anastomotic leakage remains the most devastating postoperative complication in colorectal surgery. The mechanical integrity of the newly formed colorectal anastomosis can be evaluated by visual inspection intraoperatively; both air leak and liquid leak tests are also used to evaluate the integrity of stapled colorectal anastomoses. It is not clear whether double-stapled anastomoses are more prone to leaks than single-stapled anastomoses. The aim of our study was to compare the methylene blue and the air leak test in the experimental setting of single-stapled and double-stapled porcine bowels. Methods: Twenty-four distal colons were excised from slaughtered pigs without delay. The proximal bowel end was closed with a linear stapler using blue cartridges. The bowels were randomly divided into single-stapled or double-stapled groups. Air leak and methylene blue leak tests were performed. A digital pressure monitor with a gradual pressure increase function was used to both gradually increase pressure within the bowel and to determine the pressure at which the stapler line disintegrated. Results: Air leakage occurred at a mean pressure of 51.62 (±16.60) mm Hg and methylene blue leakage occurred at 46.54 (±16.78) mm Hg ( p = 0.31). The air and methylene blue leaks occurred at comparable pressures in single-stapled bowels and in double-stapled bowels (47.21 [±14.02] mm Hg vs. 50.96 [±19.15] mm Hg, p = 0.6). Conclusions: The methylene blue solution leak test is not inferior to the air leak test. There is no significant difference in bursting pressure between single-stapled and double-stapled anastomoses.