To investigate the incidence and distribution of Rokitansky-Aschoff sinus (RAS), RAS stone (RASS) and gallbladder adenomyosis (ADM) in the gallbladder wall, and to preliminarily unravel the mechanism of RASS and ADM.

In this prospective study, gallbladder specimens were collected from 70 patients who underwent laparoscopic cholecystectomy in BenQ Medical Center Affiliated to Nanjing Medical University from September 2017 to September 2019. Among them, 34 patients were male and 36 female, aged from 24 to 82 years, with a median age of 51 years. The informed consents of all patients were obtained and the local ethical committee approval was received. The gallbladder was cut into 4 parts: cystic duct, neck, body and bottom. The incidence and distribution of RAS, RASS and ADM in the gallbladder wall were observed by naked eyes and pathological microscope. The incidence of RASS and its correlation with the distribution pattern were compared by Chi-square test.

Among 70 gallbladder specimens, the incidence of RASS in the gallbladder wall was 27%(19/70). Under microscope, the overall incidence of RAS was 86%(60/70), 39%(27/70) for simple RAS, the incidence of RASS was 30%(21/70) and the incidence of ADM was 60%(42/70), respectively. The incidence of RAS in the cystic duct, neck, body and bottom was 44%(31/70), 61%(43/70), 71%(50/70) and 66%(46/70), respectively. Microscopically, the distribution of RAS in the cystic duct and neck was significantly correlated with that of RASS (χ²=4.399, 4.747; P<0.05), which was also correlated with the overall distribution of ADM in the gallbladder (χ²=4.432, P<0.05). The incidence of RASS under microscope in male patients was 44%(15/34), significantly higher than 17% (6/36) in female counterparts (χ²=6.280, P<0.05). Under naked eyes and microscope, the incidence of RASS in patients aged ≥61 years was 43%(10/23) and 35%(8/23), respectively, significantly higher compared with 19%(9/47) and 28%(13/47) in those aged <61 years (χ²=4.622, 4.096; P<0.05). The incidence of RASS under naked eye in the gallbladder wall of patients with melanin-like stones was 70%(7/10), significantly higher than 17%(8/46) in those with cholesterol-like stones (χ²=11.593, P<0.05).

RAS is evenly distributed in the cystic duct, neck, body and bottom of gallbladder. The incidence of RASS and ADM is probably associated with RAS. Male, aged ≥61 years and patients with melanin-like stones are more likely to develop RASS.