End-to-Side Ileo-Sigmoid Anastomosis and Late Onset Gangrenous Diverticulitis: A Case Report

End-to-side ileo-sigmoid anastomosis converts the proximal colon into a blind intestinal segment which is excised during the surgery. If we do not resect the proximal colon, it is expected to behave like a colonic diverticulum, but direct evidence of this assumption is lacking. During an exploratory laparotomy, we detected an end-to-side ileo-sigmoid anastomosis and found that the proximal colon was gangrenous. The patient passed away during the postoperative period, yet their remarkably long period of symptom-free survival remained intriguing.