Beware the contracted gallbladder - Ultrasonic predictors of conversion

Pre-operative ultrasound is the gold standard pre-operative investigation for patients undergoing a cholecystectomy. Ultrasound provides a sensitive approach for analysing characteristics of the gallbladder. Thus, we aimed to examine the importance of ultrasonic gallbladder characteristics on laparoscopic cholecystectomy conversion rates and then sought to devise a pre-operative predictive score for conversion based on our findings.

A retrospective analysis of patients undergoing a laparoscopic cholecystectomy was performed between January 2000 and December 2006. Patient demographic data and pre-operative imaging results from abdominal ultrasounds were analysed. We then devised a pre-operative predictive score for conversion based on independent variables derived from multivariate analysis.

A total of 1061 patients underwent a laparoscopic cholecystectomy. Conversion to an open procedure was required in 58 cases. The overall conversion rate was 5.4%. Univariate analysis revealed male gender (p < 0.0001), gallbladder wall thickness >4 mm (p = 0.0024), a contracted gallbladder (p = 0.005) and a dilated CBD (p = 0.0416) as being significantly associated with conversion. These variables were then evaluated using multivariate analysis and three variables, namely, male gender, a contracted gallbladder and a thickened gallbladder wall were identified as independent predictors. A pre-operative predictive score for conversion was devised from a training cohort (n = 761) and tested on a sub-cohort (n = 300). Patients with a score of 2 or more had a 19.2% risk of conversion (p < 0.001).

Conversion to an open cholecystectomy shows a strong associated with gallbladder ultrasonic characteristics which are available pre-operatively. The likelihood of conversion can be accurately predicted using a pre-operative scoring system.