Introduction : Optimal timing of percutaneous transhepatic gallbladder drainage (PTGBD) and subsequent laparoscopic cholecystectomy (LC) according to the severity of acute cholecystitis (AC) is not established.

Methods : Total 739 patients with AC without common bile duct stone who underwent PTGBD and subsequent LC from January 2010 to December 2019 were retrospectively reviewed. We defined difficult surgery (DS; open conversion, subtotal cholecystectomy, adjacent organ injury, transfusion, operative time≥ 90 minutes, or estimated blood loss≥ 100 milliliters) and poor postoperative outcomes (PPO; postoperative hospital stays≥ 7 days, or postoperative complication ≥ grade II). The receiver operating characteristic (ROC) analyses were performed for evaluating appropriate duration from onset of symptom to PTGBD (duration A) and from PTGBD to LC (duration B).

Results : Of the 739 patients, 458 were for grade I AC, and 281 were for grade II/III AC. In grade I AC, the cut-off value for the relationship between duration A and PIO was 4.5 days. The cut-off value for the relationship between duration B and PPO was 7.5 days. In multivariate analysis, duration A≥ 5days and duration B≥ 8days were statistically significant predictors for DS and PPO, respectively. In grade II/III AC, the cut-off value for the relationship between duration A and PPO was 2.5 days. In multivariate analysis, duration A≤ 2days was statistically significant predictor for PPO.

Conclusions : Optimal timing of PTGBD and LC is for duration from onset of symptom to PTGBD ≤4days with duration from PTGBD to LC ≤7days in grade I AC, and for duration from onset of symptom to PTGBD >2days