Preoperative ultrasound to predict conversion in laparoscopic cholecystectomy

Laparoscopic cholecystectomy (LC) is the established treatment for symptomatic cholelithiasis. With its decreased postoperative stay, it is being performed increasingly in short-stay or outpatient settings. It is particularly important to identify preoperative factors that may predict conversion to open cholecystectomy (OC) at LC, with its concomitantly prolonged hospital recovery. In this series of 738 patients, the ultrasound features of stone size, gallbladder wall thickness, diameter of the common bile duct, number of stones, and the appearance of a contracted gallbladder were assessed preoperatively in all patients. The overall conversion rate was 3.5% (26 of 738). By logistic regression analysis, factors found to increase significantly the risk of conversion were patient age > 70 years (p < 0.01), a stone at least 20 mm in diameter (p < 0.05), a gallbladder wall thicker than 4 mm (p < 0.05), a common bile duct wider than 6 mm (p < 0.05), and contracted gallbladder on ultrasound (p < 0.02). The number of stones in the gallbladder was not significant. Using these risk factors, it was possible to divide patients into high- and low-risk groups. The 118 patients in the high-risk group had 18 of the 26 conversions, for a conversion rate of 15.3%. The 620 patients in the low-risk group had eight of the 26 conversions, for a conversion rate of 1.3%. This low-risk subgroup represented 84% of the series of 738 LC procedures and may have been suitable for outpatient LC. Using preoperative ultrasound, it is possible to predict patients who are at low risk of conversion and are suitable for ambulatory surgery.