Utility of lavage alkaline phosphatase in detection of isolated small intestinal injury.

The ability of lavage alkaline phosphatase (LAP) to detect small intestinal injury was studied in 81 patients who underwent diagnostic peritoneal lavage following blunt and penetrating abdominal trauma. Patients with a grossly positive lavage were excluded. The LAP of five patients with small intestinal injury (79.0 +/- 41.7 IU/L) was significantly greater than in 76 cases without (1.2 +/- 0.4 IU/L; P less than .05). LAP greater than or equal to 3 was seen in six patients. Four had isolated small intestinal pathology, and one had combined small and large bowel injury. In three of these five, other lavage values were normal. One possible false positive occurred. The sensitivity of LAP greater than or equal to 3 (100%) exceeded that of usual lavage parameters in the detection of small intestinal injury. LAP may be a sensitive marker for small intestinal pathology in the immediate postinjury period.