Predicting conversion from laparoscopic to open cholecystectomy presented as a probability nomogram based on preoperative patient risk factors

• First study presenting a predictive model for probability of conversion as nomograms.
• Two clinical variables, previous upper abdominal surgery and obesity, were significantly associated with conversion.
• Three ultrasound variables, choledocholithiasis, impacted stone at the neck of the gallbladder, and gallbladder wall width, were significantly associated with conversion.
• Four evidence-based probability nomograms were developed as a practical individual risk stratification tool to predict probability of conversion.

BackgroundWe aim to develop a risk stratification tool to preoperatively predict conversion (CONV) from a laparoscopic to open cholecystectomy.MethodsMultiple risk factors were analyzed with multivariate logistic regression and presented as probability nomograms.ResultsOf 732 patients, 47 (6.4%) required CONV. Among 40 preoperative risk factors evaluated, 5 variables were found to have significant association with CONV: 2 clinical variables, previous upper abdominal surgery (odds ratio [OR] 95.2) and obesity defined as body mass index greater than 30 kg/m2 (OR 12.3), and 3 ultrasound parameters, visible choledocholithiasis (OR 19.8), impacted stone at the neck of the gallbladder (OR 5.9), and gallbladder wall width in millimeters (OR 2.1). Nomograms based on this multivariate model demonstrate the individual preoperative probability of CONV. Internal validation using receiver operator curve analysis showed an area under the curve of .97.ConclusionFour probability nomograms were developed as a practical individual risk stratification tool to predict probability of CONV.