The formation process and mechanism of gastrointestinal anastomosis after retrieval anchor-assisted endoscopic ultrasound-guided gastroenterostomy: a preclinical study

Background and aims Endoscopic ultrasound-guided gastroenterostomy (EUS-GE) is a promising method of treating gastric outlet obstruction. However, no study has investigated gastrointestinal anastomosis formation after EUS-GE. We aimed to evaluate the formation of gastrointestinal anastomosis after EUS-GE in a porcine model. Methods Retrieval anchor-assisted EUS-GE was performed on 15 Bama mini pigs. Five pigs each were randomly euthanized 3, 7, and 14 days postoperatively to evaluate the formation of gastrointestinal anastomosis and measure the anastomotic distance. The expression of transforming growth factor-beta 1(TGF-beta 1) and Smad3 in the anastomosis site were examined by immunohistochemistry. Results EUS-GE was successfully performed in all 15 pigs. The mean procedure time was 29.2 +/- 6.0 (range 18-40) minutes. The anastomotic distance was 34.0 +/- 3.6 cm in 14 pigs. The site of gastroenterostomy of one pig was at the ileum. For pigs euthanized 3 days postoperatively, the structure was mechanically maintained by a stent. For pigs euthanized 7 or 14 days postoperatively, the stomach and small intestine were anastomosed to form a stable structure. The level of TGF-beta 1 and Smad3 in the anastomosis site gradually increased from 3 to 14 days after EUS-GE. TGF-beta 1 and Smad3 expression had a significant difference between 3 days, 7 days, and 14 days after EUS-GE (P < 0.05). Conclusions For EUS-GE, the stomach and small intestine were initially linked together mechanically and spontaneously anastomosed to form a stable structure 7 days postoperatively. TGF-beta 1 and Smad3 play an important role in the formation of a stable structure of gastrointestinal anastomosis.