γ-Guided diagnostic peritoneal lavage for detection of bowel perforation

Hypothesis: Bowel perforation can be diagnosed by detection of orally administered technetium Tc 99m sulfur colloid (^99mTc SC) in diagnostic peritoneal lavage (DPL) fluid using a handheld γ-detection probe. Design: A canine intestinal-injury model was used to test the hypothesis. The ^99mTc SC (55.5 MBq) was administered in 500 mL of saline via a nasogastric tube. A DPL with 500 mL of saline was performed at 60, 90, and 120 minutes after administration of ^99mTc SC. The radioactivity in the DPL effluent was measured using a hand-held γ probe. A DPL effluent count that was 3 SDs above the background count was considered a positive test result. Twenty animals with perforation and 5 without perforation (negative control) were studied. Results: There were no false-positive γ-DPL test resuits. Sensitivity improved by time up to 90 minutes. The lowest positive count in the DPL effluent measured by the γ probe corresponded to 0.2% of the administered activity. No radioactivity was detected in blood and urine samples or liver and spleen specimens. The sensitivity, specificity, accuracy, positive predictive values, and negative predictive values at 90 minutes were 95%, 100%, 96%, 100%, and 83%, respectively. Conclusions: γ-Guided DPL is a highly sensitive and 100% specific test in the detection of small-bowel perforation. Clinical studies are warranted to determine the patient-specific factors affecting diagnostic accuracy.