Introduction Laparoscopic cholecystectomy (LC) is considered difficult in patients with an impacted gallstone (IG). We examined the efficacy of releasing an IG after percutaneous transhepatic gallbladder drainage (PTGBD) for acute cholecystitis (AC) and the usefulness of the Difficulty Score (DS) proposed in the Tokyo Guidelines 2018. Methods Data were collected from 28 patients who underwent LC after PTGBD for AC caused by an IG in our department. The IG was released by flushing the gallbladder with saline or performing cholecystography. Release of the IG was evaluated based on cholecystography or drainage findings. Surgical outcomes were evaluated by comparing whether the IG could be released. Results Nine patients had an IG (IG group) and 19 had a released IG at the time of surgery. Operation time was significantly longer (P = .008), Critical View of Safety score was significantly lower (P = .019), and DS was significantly higher (P < .001) in the IG group. In multivariate analysis, DS was the only independent factor for operation time (odds ratio = 8.943, 95% confidence interval 1.179‐167.032; P = .033). Conclusion Releasing an IG may reduce surgical difficulty and maintain surgical safety. DS can be useful in predicting surgical outcomes. Highlight Fujinaga and colleagues report that releasing impacted gallstones after percutaneous transhepatic gallbladder drainage shortened the operation time, increased the Critical View of Safety score, and decreased the Difficulty Score proposed in the Tokyo Guidelines 2018. These findings suggest that releasing impacted gallstones may reduce surgical difficulty and ensure surgical safety.