Neonatal pneumoperitoneum without significant adventitious pulmonary air: use of metrizamide to rule out perforation of the bowel.

Pneumoperitoneum in the neonate may be due to air that has dissected from the chest. Four infants, in whom pneumoperitoneum, from thoracic air dissection, occurred in the absence of pneumothorax or pneumomediastinum are reported. The absence of abnormal collections of air in the chest is of no value in deciding whether a pneumoperitoneum is due to bowel perforation or air dissecting from the chest. Contrast bowel studies are needed in all cases of pneumoperitoneum in the infant to distinguish bowel perforation from intrathoracic origin of the air.