An unusual colo-ovarian fistula of advanced colorectal carcinoma: A case report and literature review.

In colorectal cancer, the invasion of the colon is not unusual, but the perforation of all layers of the colon or rectum and the presentation of the patient with generalized peritonitis is rare. Colo-ovarian fistulas have as their starting point either in the sigmoid colon, rectum, appendix or, more frequently, as a benign or malignant ovarian tumor. The present study reports an extremely rare case of colorectal cancer with perforation at the rectosigmoid junction into a metastatic ovarian tumor. Intraoperatively, a colo-ovarian fistula with diffuse peritonitis was diagnosed. The treatment consisted of a hysterectomy with bilateral salpingo-oophorectomy, and the resection of the colo-ovarian fistula was performed using the Hartmann procedure. The prognosis was poor due to the advanced stage of colorectal cancer and complications from peritonitis. Due to the rarity of this pathology, an extensive electronic search and an analytical review of studies published in the PubMed and Web of Science databases was performed, identifying 21 eligible studies on malignant colo-ovarian fistula (11 cases due to advanced stages of primary ovarian cancer and 10 cases of malignant transformation of cystic teratoma) and no case in which the primary tumor was of colorectal origin. Based on the literature review, the current case report aimed to obtain and present a better understanding of the pathology, differential diagnosis, therapeutic strategy and prognosis of the condition.