["Disappearance" of retroperitoneal vessels - a case report].

: We report the ultrasound findings in a case of pneumo-retroperitoneum. The 74-year-old patient was admitted because of severe dyspnoea. Chest X-ray revealed a left-sided pleural effusion, and a drainage was performed. Later on the patient for the first time complained about severe pain in the lower abdomen. Ultrasound of the abdomen was performed. Sonographically, it was remarkably difficult to obtain images of the right kidney and the retroperitoneal vessels, as massive reverberation artifacts in the retroperitoneum were present. Plain radiography of the abdomen revealed free retroperitoneal and intraabdominal gas. At laparotomy a perforated diverticulitis of the sigma was discovered. Postoperative follow-up was uneventful, but the recurrent pleural effusion was later confirmed to be due to a malignant mesothelioma. This article discusses the characteristic sonomorphologic features of pneumo-retroperitoneum and its differential diagnosis. Although free retroperitoneal air is a rare condition, it is crucial for the examiner to be aware of the characteristic sonographic findings in order to initiate appropriate therapy.