The value of alkaline phosphatase in peritoneal lavage

The accuracy of peritoneal lavage for diagnosis of intra-abdominal injury in trauma is limited by its relative lack of sensitivity for hollow viscus injury. Peritoneal lavage in the dog indicates that alkaline phosphatase is an early marker of intestinal injury. If these results were confirmed in human patients, alkaline phosphatase determination would improve lavage sensitivity for hollow viscus injuries. A study was conducted to determine the usefulness of alkaline phosphatase in lavage in human beings. Alkaline phosphatase was measured in all trauma lavage samples sent for laboratory assay during a one-year period. Two hundred ninety-two lavages were performed: 25 were positive by laboratory criteria, and 66 were grossly positive. There were 13 intestinal injuries--nine were grossly positive, and four were diagnosed by laboratory results. Three of these four patients with intestinal injuries had elevated lavage alkaline phosphatase. All three (lavaged from 30 minutes to two hours after injury) also had elevated white blood cells or bile in the lavage fluid. The remaining intestinal injury was diagnosed by lavage bile but had no elevation of alkaline phosphatase (lavaged 15 minutes after injury). Two patients with elevated alkaline phosphatase in otherwise negative lavages were observed for at least five days; neither demonstrated any evidence of intra-abdominal injury. We conclude that alkaline phosphatase is no better than traditional determinants of intestinal injury in peritoneal lavage. In no patient was alkaline phosphatase helpful in diagnosing a hollow viscus injury, and its use would have prompted two unnecessary laparotomies. These data do not support the use of lavage alkaline phosphatase to identify hollow viscus injuries.