Abstract
Intestinal nonrotation is a rare congenital anomaly resulting from incomplete midgut rotation during embryogenesis. Adult cases represent only 0.2% of the incidence of the disease. Familial adenomatous polyposis (FAP) is an inherited condition characterized by hundreds of colorectal adenomas and a near-100% lifetime risk of colorectal cancer. The coexistence of these two conditions has not been previously reported. A 28-year-old male presented with rectal bleeding. Laboratory evaluation revealed severe anemia and thrombocytopenia. Computed tomography revealed incidental intestinal nonrotation, with small bowel on the right and colon on the left, along with inversion of the superior mesenteric artery and vein. Sigmoidoscopy showed extensive polyposis consistent with FAP. The patient underwent laparoscopic total colectomy with ileorectal anastomosis. This case underscores the importance of identifying congenital anomalies such as nonrotation, and also reinforces the preoperative imaging as critical in anticipating anatomical variations, enabling careful surgical planning, and vessel preservation.