Contemporary Predictors of Conversion from Laparoscopic to Open Appendectomy

Abstract

We defined the contemporary conversion rate from laparoscopic appendectomy (LA) to open appendectomy and identified pre-operative factors associated with conversion. Retrospective review of 941 consecutive LAs performed for suspected acute appendicitis in a single urban university hospital between 2000 and 2007. Patient characteristics, clinical features, physical examination findings, laboratory values, computed tomography (CT) findings, surgeon identity, operative findings, and pathologic results were assessed. Categorical variables were compared in patients undergoing LA and those in whom conversion was necessary using the Fisher exact test; the Student t-test was used to compare continuous variables. Multivariable analysis was performed with binomial logistic regression. Statistical significance was established at α = 0.05. The overall conversion rate was 4.1% and did not change significantly over the course of the study. By univariable analysis, conversion was significantly associated with older age, male gender, American Society of Anesthesiologists (ASA) score >2 points, longer duration of symptoms, rigidity on physical examination, increased percentage of neutrophils on admission white blood cell differential count, extraluminal air on CT, inexperience of the attending surgeon with LA, retrocecal location of the appendix, gross necrosis or perforation, murky or purulent ascites, and microscopic evidence of perforation. By multivariable analysis, advanced age (hazard ratio [HR] 1.02 per year; 95% confidence interval [CI] 1.01-1.04, p = 0.02), ASA score >2 points (HR 11.2; 95% CI 5.6-24.4; p < 0.001), CT inflammation grade ≥ 4 (HR 4.8; 95% CI 1.9-12.3; p = 0.001), and attending surgeon inexperience (HR 7.4; 95% CI 2.6-20.8; p < 0.001) were independent predictors of conversion. The conversion rate during laparoscopic appendectomy has not changed significantly over the past seven years and remains ~4%. Independent pre-operative predictors of conversion are advanced age, ASA score >2 points, attending surgeon inexperience, and extensive inflammation observed on pre-operative CT scan. Proceeding directly with open appendectomy under these circumstances may reduce operative time, expense, and morbidity.