Gas-filled Umbilical Hernia
(Pneumo-umbilicus). A CT Sign of
Hypertensive Pneumoperitoneum

Several signs of pneumoperitoneum, related to the diaphragmatic domes, right upper quadrant, lesser sac, and lower abdomen, have been recognised by using first plain abdominal radiographs and later Computed Tomography (CT).

These findings are especially evident when an abundant, eventually tension, valvular pneumoperitoneum is present (Addison N et al, Br J Surg 1976; 63 : 877). In this case the gas under pressure distends the peritoneal spaces, ligaments and folds, elevates the diaphragm, compresses the viscera, and eventually dissects through all possible pathways, including the retroperitoneum or a patent inguinal canal (Bray JF, Br J Radiol 1982; 55: 867, Cho KC et al, Radiology 1997; 202: 651, Grassi R et al, Br J Radiol 1996; 69: 774). We add another occurrence; an encapsulated gas collection within the umbilical area demonstrated by helical CT in a subject with tension pneumoperitoneum. To the best of our knowledge this sign, which we named “pneumo-umbilicus”, has not been reported previously.