BACKGROUND: While it is well known that abdominal wall hernias can pose obstacles for colonoscopy, these may not be obvious in obese patients, particularly when the hernia is in an unusual place.

CASE REPORT: A 62-year-old man presented with inability to complete colon cancer screening by means of colonoscopy or barium enema. On exam, he was noted to have a Spigelian hernia present in his left lower quadrant abdominal wall. CT colonography identified incarcerated sigmoid colon within the hernia accounting for his inability to complete colonoscopy or barium enema. Repair of his Spigelian hernia was thus performed, allowing for ease of future colorectal cancer screening.

CONCLUSIONS: Colorectal cancer screening is an evidence-based benchmark for effective primary care, but is often ordered and interpreted like a blood test, without reference to the technical aspects of the procedure. Failure of colonoscopy requires examination of the patient and consideration of why the procedure failed. In particular, patients in whom colonoscopy fails must be carefully evaluated for occult partially obstructing hernias.

Keywords: Colonography, Computed Tomographic, Colonoscopy, Colorectal Neoplasms, Hernia, Abdominal