Anterior left subphrenic abscess: characteristic plain film and CT appearance.

Abdominal abscesses located in the left upper quadrant may occur in two major anatomic locations, the subphrenic space or the lesser sac. The left coronary or triangular ligament extending from the dorsal aspect of the liver to the diaphragm separates the subphrenic space from the lesser sac. As the ligament usually extends posteriorly, the anterior subphrenic space extends under the dome of the diaphragm, occupying the most superior part of the left upper quadrant. Both the lesser sac and the left anterior subphrenic space extend to the right of midline. The left anterior subphrenic compartment is bounded on the right by the falciform ligament while the lesser sac extends to the right coronary ligament and foramen of Winslow. Therefore, abscesses either in the left anterior subphrenic compartment or lesser sac may extend across the midline into the right upper quadrant. Left anterior subphrenic abscesses will be immediately subdiaphragmatic while lesser sac abscesses extending to the right of midline will not usually extend up to the diaphragm. Six cases are presented demonstrating midline air-fluid levels and soft-tissue masses in the immediate subdiaphragmatic area, characteristic signs of anterior left subphrenic abscesses.