Irrigation versus suction alone during laparoscopic appendectomy; A randomized controlled equivalence trial

The objective of this study was to compare operative peritoneal irrigation versus suction alone during laparoscopic appendectomy in adult patients; our hypothesis was that the two methods are equivalent in terms of rate of post-operative intra-abdominal abscess. There has been only one prospective, randomized, superiority trial in children, that showed non-significant difference in the rate of intra-abdominal abscess comparing irrigation to suction alone during laparoscopic appendectomy for perforated appendicitis. Non-significant difference in a superiority trial does not imply equivalence.

This was a single-institution, prospective, randomized controlled equivalence study based on a null-hypothesis of non-equivalence between irrigation and suction alone. Adult patients with intra-operative findings of an acutely inflamed appendix, with suppuration or perforation localized to the right iliac fossa, paracolic gutter or pelvis were randomized to irrigation or suction alone. The primary endpoint was the rate of intra-abdominal abscess. An unconditional exact test of equivalence was used to test the null-hypothesis.

Eighty-one patients were included for analysis. Two (5%) of 40 patients in the irrigation group and two (4.9%) of 41 in the suction-only group developed postoperative intra-abdominal abscess. The 95% confidence interval for the difference between the two groups was -0.1200 to 0.1244, captured within the pre-defined δ limits (-0.15, 0.15). With reference to the rate of intra-abdominal abscess, equivalence was demonstrated between irrigation and suction-only techniques.

In patients with suppurative or perforated appendicitis, the rate of intra-abdominal abscess is equivalent between groups treated with peritoneal irrigation and suction alone.