Is mechanical bowel preparation necessary before primary colonic anastomosis? An experimental study

The necessity of preoperative or intraoperative mechanical bowel preparation of the colon, before primary anastomosis, has been recently challenged in clinical elective and emergency situations.

This experimental study in dogs investigated the safety of segmental resection and primary anastomosis in the unprepared or loaded colon.

Two segments of the descended colon were resected and anastomosed in each animal. Group I (12 anastomoses) received preoperative mechanical bowel preparation; the colon was not prepared in Group II (16 anastomoses); in Group III (12 anastomoses), a preliminary distal colonic obstruction was produced, and during the subsequent resection the colon was loaded. Postoperatively, animals were observed clinically, and anastomoses were assessed at autopsy on the ninth day.

All animals recovered uneventfully. At autopsy there was no evidence of anastomotic leakage.

In light of recent clinical reports and this experimental study, the ritual of mechanical bowel preparation should be further scrutinized.