Mucosal intussusception to avoid ascending cholangitis. Many methods have been devised to prevent ascending cholangitis following Kasai's hepatic portoenterostomy for biliary atresia. To investigate the effectiveness of mucosal intussusception in preventing ascending cholangitis, 20 mongrel dogs were randomized to undergo Roux-en-Y cholecystjejunostomy and common bile duct ligation with or without mucosal intussusception. Aeromonas hydrophila was instilled into the gastrointestinal tract. Bacterial cultures were grown from samples taken from the gallbladders and lower jejunum, and blood chemistry and barium studies were performed. The barium studies showed satisfactory lack of reflux in all ten dogs with mucosal intussusception. Only two of them had positive cultures for Aeromonas from the gallbladder 3 days after bacterial instillation into the jejunum. All ten dogs in the control group had positive cultures for Aeromonas from the gallbladder. Our results showed that the mucosal intussusception group had a significantly lower rate of recovery of organisms from the gallbladder compared with the control group when the organisms were instilled into distal intestine (P less than 0.05). The method is worthy of clinical trial as a means of preventing or treating ascending cholangitis. 