When the abdomen misleads: Emphysematous pyelonephritis masquerading as pneumoperitoneum.

A presentation in septic shock with tense abdominal distension and left flank pain, combined with a plain radiograph showing massive subdiaphragmatic free air usually suggests perforation of a hollow viscus. A CT scan obtained before laparotomy was undertaken, showing gas destroying the left renal parenchyma with extension into the pararenal space and rupture through the posterior parietal peritoneum with an intact gastrointestinal tract. Laparotomy was thus avoided; pneumoperitoneum is not always gastrointestinal in origin.