Fig. 1

Intraoperative images of the three different LAISR approaches. a–c Laparoscopic transabdominal approach for intersphincteric resection (TAISR). a Inferior mesenteric artery was transected at the root. b Hiatal ligament was dissected and transected at the posterior side. c Tissue was separated along the puborectalis and internal sphincter to the deep and superficial parts of the external sphincter, and a coloanal anastomosis was performed. J: Puborectalis muscle k: Deep external sphincter muscle l: Superficial external sphincter muscle. m: Rectal stump. d–f Laparoscopic transabdominal perineal approach for intersphincteric resection (TPAISR). d Circumferential incision of the rectal mucosa into the intersphincteric space. e Prolapse of the rectum after complete rectal dissociation along the sphincter space. f Colonic anal canal or rectal anal canal anastomosis was performed through the perineum. g–i Laparoscopic transanal pull-through approach for intersphincteric resection (PAISR). g Pull-through of the distal rectum with two rubber tubes. h Transection of the distal intestine under direct vision. i Tumor specimen was intact, and the distal margin was clearly visible