Total bilirubin amount in drainage fluid can be an early predictor for severe biliary fistula after hepatobiliary surgery.

The ratio of the bilirubin concentration in abdominal drainage fluid to the serum bilirubin concentration (d-Bil/s-Bil) has been used as a predictor of biliary fistula (BF) formation after hepatobiliary surgery. The d-Bil/s-Bil ratio is highly influenced by the amount of drainage and is not always reliable, especially when the amount of drainage is large. In this study, the usefulness of the d-Bil/s-Bil ratio and total bilirubin amount in the drainage fluid (TBA) (bilirubin concentration in the drainage fluid x the amount of drainage) as predictors of severe BF (sBF) formation was evaluated retrospectively from the data of 306 patients who had undergone hepatobiliary surgery. Of the 306 patients, 201 patients were included in the training set and the remaining 105 in the validation set, to determine the best parameter to predict sBF formation after hepatobiliary surgery. Receiver-operating characteristic curve analysis revealed that the predictive power of TBA was superior to that of the d-Bil/s-Bil ratio throughout the postoperative period, and that the TBA on postoperative day (POD) 1 showed the highest discriminatory power in the training set (area under the curve, 0.789; cutoff value, 470 mg/day). The TBA on POD 1 also showed the highest predictive power for sBF formation in the validation set, with a sensitivity of 100%, specificity of 97.1%, and accuracy of 97.1%. In conclusion, TBA may be a more reliable predictor of sBF than the conventionally used d-Bil/s-Bil ratio. Early prediction of sBF may be useful for early removal of unnecessary prophylactic drainage tubes after hepatobiliary surgery.