A new experimental model of calculous cholecystitis suitable for the evaluation and training of minimally invasive approaches to cholecystectomy.

Background: Novel, less invasive approaches such as single-incision laparoscopic cholecystectomy or natural orifice transluminal endoscopic surgery require preclinical evaluation and training. Therefore, there is a need for an experimental model closely mimicking the clinical situation. The aim of our study was to create an experimental model of calculous cholecystitis in a large laboratory animal and test its feasibility for the evaluation of different techniques of cholecystectomy.

Methods: In 11 laboratory pigs, gallstones were placed inside the gallbladder laparoscopically. Levels of inflammatory markers-leucocytes (WBC), C-reactive protein (CRP) and interleukin 6 (IL-6)-were monitored on the postoperative days (POD) 1, 2, 3, 7 and 30. Abdominal ultrasound was performed 2 and 4 weeks after the operation. Four weeks after the lithiasis induction, laparoscopic cholecystectomy was performed. The control group consisted of ten healthy animals in which a cholecystectomy was performed. The pigs were monitored for 30 days after surgery. All removed gallbladders were assessed histologically.

Results: The induction of lithiasis took 42 (35-52) min with no morbidity and mortality. The values of WBC, CRP and IL-6 increased significantly (vs. baseline) on POD 1, 2 and 3 (p < 0.05) and then normalised. Ultrasonography confirmed the presence of chronic calculous cholecystitis in all cases after 4 weeks. Laparoscopic cholecystectomy was significantly longer in animals with lithiasis, 63 (42-91) versus 46 (31-62) min (p = 0.018). Perioperative gallbladder wall perforation was significantly more frequent in the model group (8/11 vs. 1/10; p = 0.04). In contrast to healthy animals, all gallbladders with stones showed histological signs of chronic inflammation.

Conclusions: A new animal model of calculous cholecystitis was created. Laparoscopic cholecystectomy was more technically difficult compared to operating on a healthy gallbladder. This model may be a suitable tool for effective preclinical training and also for the evaluation of different techniques of cholecystectomy.