Abdominal drainage to prevent intra-peritoneal abscess after appendectomy for complicated appendicitis

This is the second update of a Cochrane Review first published in 2015 and last updated in 2018. Appendectomy, the surgical removal of the appendix, is performed primarily for acute appendicitis. Patients who undergo appendectomy for complicated appendicitis, defined as gangrenous or perforated appendicitis, are more likely to suffer postoperative complications. The routine use of abdominal drainage to reduce postoperative complications after appendectomy for complicated appendicitis is controversial.

To assess the safety and efficacy of abdominal drainage to prevent intraperitoneal abscess after appendectomy (irrespective of open or laparoscopic) for complicated appendicitis; to compare the effects of different types of surgical drains; and to evaluate the optimal time for drain removal.

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), Ovid MEDLINE, Ovid Embase, Web of Science, the World Health Organization International Trials Registry Platform, ClinicalTrials.gov, Chinese Biomedical Literature Database, and three trials registers on 24 February 2020, together with reference checking, citation searching, and contact with study authors to identify additional studies.

We included all randomised controlled trials (RCTs) that compared abdominal drainage versus no drainage in people undergoing emergency open or laparoscopic appendectomy for complicated appendicitis. We also included RCTs that compared different types of drains and different schedules for drain removal in people undergoing appendectomy for complicated appendicitis.

We used standard methodological procedures expected by Cochrane. Two review authors independently identified the trials for inclusion, collected the data, and assessed the risk of bias. We used the GRADE approach to assess evidence certainty. We included intraperitoneal abscess as the primary outcome. Secondary outcomes were wound infection, morbidity, mortality, hospital stay, hospital costs, pain, and quality of life.

Use of drain versus no drain We included six RCTs (521 participants) comparing abdominal drainage and no drainage in participants undergoing emergency open appendectomy for complicated appendicitis. The studies were conducted in North America, Asia, and Africa. The majority of participants had perforated appendicitis with local or general peritonitis. All participants received antibiotic regimens after open appendectomy. None of the trials was assessed as at low risk of bias. The evidence is very uncertain regarding the effects of abdominal drainage versus no drainage on intraperitoneal abscess at 30 days (risk ratio (RR) 1.23, 95% confidence interval (CI) 0.47 to 3.21; 5 RCTs; 453 participants; very low-certainty evidence) or wound infection at 30 days (RR 2.01, 95% CI 0.88 to 4.56; 5 RCTs; 478 participants; very low-certainty evidence). There were seven deaths in the drainage group (N = 183) compared to one in the no-drainage group (N = 180), equating to an increase in the risk of 30-day mortality from 0.6% to 2.7% (Peto odds ratio 4.88, 95% CI 1.18 to 20.09; 4 RCTs; 363 participants; low-certainty evidence). Abdominal drainage may increase 30-day overall complication rate (morbidity; RR 6.67, 95% CI 2.13 to 20.87; 1 RCT; 90 participants; low-certainty evidence) and hospital stay by 2.17 days (95% CI 1.76 to 2.58; 3 RCTs; 298 participants; low-certainty evidence) compared to no drainage. The outcomes hospital costs, pain, and quality of life were not reported in any of the included studies. There were no RCTs comparing the use of drain versus no drain in participants undergoing emergency laparoscopic appendectomy for complicated appendicitis. Open drain versus closed drain There were no RCTs comparing open drain versus closed drain for complicated appendicitis. Early versus late drain removal There were no RCTs comparing early versus late drain removal for complicated appendicitis.

The certainty of the currently available evidence is low to very low. The effect of abdominal drainage on the prevention of intraperitoneal abscess or wound infection after open appendectomy is uncertain for patients with complicated appendicitis. The increased rates for overall complication rate and hospital stay for the drainage group compared to the no-drainage group are based on low-certainty evidence. Consequently, there is no evidence for any clinical improvement with the use of abdominal drainage in patients undergoing open appendectomy for complicated appendicitis. The increased risk of mortality with drainage comes from eight deaths observed in just under 400 recruited participants. Larger studies are needed to more reliably determine the effects of drainage on morbidity and mortality outcomes.