Article Summary: Irrigation of the abdomen in cases of significant contamination has long been a common practice in general surgery. The adage goes: “The solution to pollution is dilution.” St. Peter and colleagues have sought to prove or disprove the value of this practice in pediatric patients through a prospective randomized trial of patients with perforated appendicitis treated with laparoscopic appendectomy. 220 patients were enrolled in an IRB-approved, randomized trial over 30 months, with intent to treat. All other parameters of treatment were held as constant as possible, including antibiotics, post-operative care and feeding regimen. In patients who received irrigation, the amount of saline irrigation used was at the surgeon’s discretion and averaged nearly one liter per case (range 500-2000 ml). Only one patient crossed over from no irrigation to irrigation. All measured outcomes showed no statistically significant difference between the groups, including abscess rate (approximately 18%), operative time (+ 4 minutes for irrigation group), time to diet, length of stay and hospital charges. The authors conclude that saline irrigation offers no benefit in this group of patients.
Question 1: When early data comparing open appendectomy to laparoscopic appendectomy became available, the post-operative abscess rate in children (as compared to adults) treated laparoscopically for perforated appendicitis was reported to be much higher. The post-operative abscess rate in this study for both arms is 18-19%. Is this abscess rate unduly high, or does Dr. St. Peter’s explanation in the oral discussion that other studies do not compare comparable populations account for this complication rate? How would a study be designed to answer this question?
Question 2: This study was designed to have power to show a delta shift from 18% to over 35% in the post-operative abscess rate. Presumably, the size of the study would have to be enlarged to show a significant difference at a smaller delta. Since the abscess rates in both arms were so close, is the study sufficiently powered to answer the clinical question that authors posed?
Question 3: Given a post-operative abscess rate of 18-19%, one could argue that there must be a way to improve the outcomes and lower the abscess rate in this population. What types of interventions and studies to test them would you suggest? For example, would more irrigation or antibiotic irrigation have made a difference?
Question 4: This is a well-designed, well-controlled study for a defined population of patients. How applicable is this result to other patients with extensive peritoneal soilage from, for example, perforated bowel due to tumor, obstruction or trauma?
Please feel free to comment on any or all of the questions above. We look forward to hearing from you, the Annals readers.