Fig. 2

Main steps of surgery. a IMA was exposed and then ligated. Black arrow indicates the root of IMA. b The dissection of mesorectum in transabdominal approach. c The dissection to intersphincteric groove in transabdominal approach. d Purse-string suture was performed to expose the anus to achieve the optimal view in transanal approach. Red arrow indicates the lower edge of the tumor. e The specimen was dragged out by anus. f The tumor specimen was dissected by the linear stapler. g The applicator was pushed into the tumor bed transanally. h The applicator was put into the tumor bed by laparoscopic surveillance. White arrow points the spherical applicator in the pelvic cavity. i Wet gauzes were put to isolate and protect the adjacent structures from radiation