Diagnostic peritoneal lavage in acute peritonitis.

Fifty patients were studied prospectively to determine the value of diagnostic peritoneal lavage in the evaluation of acute peritonitis. Forty-five patients had a clinical diagnosis of acute peritonitis based on physical findings, and 5 patients were normal control subjects. All lavages were performed with an open technique in the operating room prior to laparotomy. Lavage fluid was analyzed for white and red blood cell counts, the differential, amylase, protein, bilirubin, and pH. Results were analyzed by multiple logistic regression. Thirty-two of the 45 patients with clinical peritonitis had the diagnosis confirmed at laparotomy. A white blood cell count in the lavage fluid greater than or equal to 200 cells/mm3 was associated with a 99% probability of peritonitis.