We reviewed the records of 395 patients seen from January 1983 through May 1988, who after sustaining blunt thoracoabdominal trauma had diagnostic peritoneal lavage (DPL) performed percutaneously by the Seldinger wire technique of Lazarus and Nelson. The test was considered grossly positive if 10 cc of blood were aspirated from the catheter immediately after its insertion into the peritoneal cavity. Microscopic criteria for positivity included more than 100,000 RBC or 500 WBC/cc of lavage return, elevated amylase or bilirubin, or the presence of vegetable fibers or bacteria. Seventy-two (18%) of the patients were true positives and 315 (80%) were true negatives. There were four false positives (1.3%) and one false negative (0.2%), giving the test a sensitivity of 99% and a specificity of 98%. Complications occurred in three patients, for a rate of 0.8%, and included catheter insertion into a large ovarian dermoid cyst, needle perforation of the ileum, and needle perforation of the sigmoid colon. This technique of DPL can consistently be performed much more rapidly than the open method. Therefore we conclude that percutaneous DPL is as accurate as, as safe as, and quicker than open DPL for determining intra-abdominal injury in blunt trauma patients.