Alkaline phosphatase levels in diagnostic peritoneal lavage fluid as a predictor of hollow visceral injury

Isolated injuries to hollow viscera may result in equivocal diagnostic peritoneal lavage (DPL) findings. Small bowel injuries cause alkaline phosphatase (AP) levels to increase in DPL effluent. The goal of this study was to better define the role of AP levels in the evaluation of the injured abdomen. We prospectively measured AP levels in 672 patients undergoing DPL. These were retrospectively compared with the clinical findings. All 12 patients with small bowel injuries and three of four with large bowel injuries had an AP level >10 IU/L. There was one patient with an AP level >10 IU/L without clinically significant intra-abdominal injury. An AP level >10 IU/L in the DPL effluent predicted injury requiring laparotomy with a specificity of 99.8% and a sensitivity of 94.7%. We recommend using AP levels only in the management of patients with equivocal findings on DPL who would otherwise not undergo laparotomy. This selective use of AP levels will improve the probability of early diagnosis of bowel injury without increasing the cost of care.