The retroperitoneal space is made up of multiple communicating compartments. Here we detail an unusual case of ectopic gas almost exclusively isolated to the properitoneal space, a space in communication with the retroperitoneum. This case is a reminder that when extraperitoneal gas is identified, the retroperitoneal structures should be interrogated carefully to identify a cause. Fig. 4. Axial CT images of the abdomen with PV contrast, showing the proposed origin of gas, from an ischaemic loop of bowel into either the lateral conal space or directly to the properitoneal space.