Diagnostic peritoneal lavage (DPL) is a technique designed to sample the peritoneal cavity for evidence of catastrophic pathology, while incurring minimum risk. The authors describe two unstable pediatric patients, one with acute lymphoblastic leukemia and shock and one with Fanconi anemia on high-frequency oscillation after stem cell transplantation, both presumed to have intra-abdominal perforation. DPL was uneventfully performed at the bedside in both patients. The authors suggest DPL be considered as an alternative to laparotomy in critically ill pediatric oncology and stem cell transplantation patients.