Accuracy of techniques to detect intraperitoneal abscess.

Overview

Three new diagnostic techniques, gray-scale ultrasonography, gallium-67 scanning (67Ga), and computed tomography (CT) were used in combination to detect intraperitoneal abscess in 30 patients. All 30 had sonography, 24 were scanned for 67Ga, and 15 underwent CT. Nine had three tests and 21 had two. Accuracy of results was evaluated by subsequent laparotomy in 16 and by clinical impression in the remainder. Ultrasound was accurate (true positive and true negative) in 12 of 16 (75%) operated patients, with 12% false-positive and 12% false-negative results. Gallium correctly diagnosed nine of 14 (64%) operated patients having 22% false-positive and 14% false-negative diagnoses. CT was accurate in five of seven (71%) patients evaluated by operation, with 14% false positives and 14% false negatives. Overall accuracies for both operated and clinical groups was ultrasound 57%, gallium 54%, and CT 67%, not significantly different results. Three tests agreed in only two of nine patients (22%), with no single test more accurate than another. Two tests agreed in 57%, with no test superior to another. It is concluded that ultrasonography, 67Ga scanning, and CT each have significant limits in diagnosing intra-abdominal pus. No single test is better than another. Disagreement among test results in the same patient obviates use of more than one technique in most instances.