[Ultrasound detection of pneumoperitoneum based on typical ultrasound morphology]

The correspondence of sonography and radiography to figure out a pneumoperitoneum was studied in a group of 140 patients having undergone abdominal surgery. Sonography revealed 14 (82.4%) out of 17 radiographically positive patients. Because of the predominant collection of free air in the right upper quadrant, the ventrolateral liver surface represents the most important region in search of a pneumoperitoneum. In another 3 patients free peritoneal gas was diagnosed which was not revealed radiographically. The possibility to observe motion in real-time sonography repeatedly proved to be decisive for the certain diagnosis of free air (the shifting air under patient's movent and the immobility of the gas reflex under respiration). An observed "step" between the air in the costophrenic sinus and the abdominal gas reflex is considered to be an additional sonographic sign. These results justify combined evaluation of a suspected pneumoperitoneum by both plain film radiography and sonography prior to other imaging modalities.