Abdominal wall hernias are a common abdominal pathology with higher prevalence in our population. It is usually asymptomatic but complications such as strangulation, incarceration or bowel obstruction need early detection and emergency surgery. The purpose of this article is to describe the infrequent type of hernia, illustrate the imaging findings and review the differential diagnosis. A 76-year-old woman was admitted in the emergency room with abdominal pain, vomits and diarrhoea. At her admission, a colonoscopy was attempted to perform but it was not possible to go beyond the stenosis. A barium enema and a multi-detector computed tomography (MDCT) were performed revealing a large mass in the left ischiorectal fossa, containing herniated loops of sigmoid colon adjacent to rectum. Abdominal wall hernias occur at areas of congenital or acquired weakness in the abdominal wall and are considered external hernias. MDCT is essential to identify wall hernias, make an accurate diagnosis and help for its clinical assessment. Knowing the radiological features of various types of abdominal hernias on MDCT and barium-enhanced radiographs allows confident diagnosis of these pathologies.