Acute Ischemic Gangrene of the Rectosigmoid Colon in a Patient With Rectal Cancer in the "Watch-and-Wait" Protocol.

Acute rectal ischemia is a rare entity because the rectum has abundant blood supply from the inferior mesenteric, internal iliac, internal pudendal, and marginal artery with rich collaterals. We present a case of an acute ischemic proctosigmoiditis with a history of rectal cancer who completely recovered after total neoadjuvant treatment and was in the "watch-and-wait" protocol. Urgent laparoscopic low anterior resection and protective ileostomy were performed. Causes of acute rectosigmoid ischemia include old age, diabetes, atherosclerosis, previous aortic surgery due to aneurysm, vasculitis, and radiotherapy. Ischemia may be present as only involving the mucosa, which can be managed conservatively, but full-thickness necrosis requires urgent surgical intervention. Endoscopic examination is the gold standard in initial diagnosis. Ischemic gangrene of the rectosigmoid colon is a rare condition and can be life-threatening unless an urgent surgical intervention is performed.