Colorectal Tumors: From Transanal Pull-through Approach to Bilateral Pelvic Osteotomy. A Critical Review

Colorectal resection should only be reserved to really aggressive tumors (high grade/ infiltrative adenocarcinoma and leiomyosarcoma). A miminum of 4-5 cm of macroscopically healthy tissue should be given in case of aggressive tumors and only after that the tumor extent has been carefully determined by endoscopy and CT scan (1). In case of less aggressive tumors (carcinoma in situ, polypoid adenocarcinoma) a not full thickness rectal excision (sparing the muscular layer) and a strict further monitoring (periodical rectal digital exploration, colonoscopy and abdomen ultrasound) may be an alternative. Conservative resection may be accomplished manually or with stapler after “pull out”, i.e. rectal prolapse through traction of full thickness stay sutures applied to distal rectum (2). However, the author strongly recommends this procedure only for distal/middle rectal lesions since an excessive traction to exteriorize more proximal lesions may result in an “uncontrolled” full thickness intrapelvic tear of the rectal wall requiring opening of the pelvis to correct it.

Amputation of different tracts of colo-rectum may be performed according to different techniques depending on tumor location, extent and complete staging (2) but major complications may develop. In general, complications may arise because of several reasons but, apart from an incorrect surgical technique, they are mainly related to impaired vascularization and tension. Rectal vascularization is provided by the cranial (from caudal mesenteric artery), middle and caudal (from internal pudendal a.) arteries. The cranial rectal a. is the most important and, if ligated, all rectum and distal colon should be eliminated (3). An impaired vascularization +/- tension may lead to potential complications such as anastomosis dehiscence (3-5 days from surgery) or permanent fibrotic stenosis resulting in protracted tenesmus, mainly in small dogs. Intrapelvic anastomotic dehiscence is a dramatic event, often leading to death or euthanasia. During healing a transient stenosis is likely to occur in all the anastomotic intestinal sites but the development of an annular and persistent fibrous ring in an anastomotic intrapelvic location is likely to result in either obstruction or protracted tenesmus requiring surgical revision or, as a minimum, balloon dilation (bougienage).  [...]