Cell count ratio: new criterion of diagnostic peritoneal lavage for detection of hollow organ perforation.

OBJECTIVES: Diagnostic peritoneal lavage (DPL) had been widely used in evaluating patients with suspected intraperitoneal injuries due to its high sensitivity. If the positive criteria are strictly followed, however, the incidence of nontherapeutic laparotomies will be unacceptably high. This realization has become more important recently with the popularization of nonoperative treatment for blunt solid organ injuries. For these patients, the early diagnosis of an associated hollow organ perforation is mandatory.
METHODS: Three hundred and twenty patients undergoing DPL over an 18-month period were retrospectively reviewed to evaluate the usefulness of "cell count ratio" in diagnosing hollow organ perforation. The cell count ratio was defined as the ratio between white blood cell count and red blood cell count in the lavage fluid divided by the ratio of the same parameters in the peripheral blood.
RESULTS: Two hundred twelve patients were diagnosed as having a positive DPL according to the classic criteria. Forty-four patients (21%) had a cell count ratio of greater than or equal to 1. The diagnosis at laparotomy was small bowel perforation in 31 patients, colon perforation in eight patients, diaphragmatic hernia in one patient, pancreatic transection in two patients, and liver laceration in two patients. None of the patients with a cell count ratio of less than I sustained hollow organ perforation. The average interval from injury to DPL was 5 hours, with the shortest being 1.5 hours.
CONCLUSION: A cell count ratio of greater than or equal to 1 predicted hollow organ perforation with a specificity of 97% and a sensitivity of 100%. The selective use of the cell count ratio has improved the probability of early diagnosis of bowel perforation without increasing the cost of care. Nonoperative management can be applied more confidently to those patients sustaining a blunt solid viscus injury of the abdomen if the cell count ratio is low. We conclude that the cell count ratio of DPL effluent is a very sensitive and specific indicator of hollow organ perforation. In the treatment of blunt abdominal injuries, if the cell count ratio is positive, nonoperative treatment should be abandoned and a laparotomy undertaken.