Abdominal distention and metabolic acidosis are common in critically ill infants and children, and can be manifestations of an intra-abdominal catastrophe. This series demonstrates the value of bedside sonography (US) in this difficult assessment. Eight infants and children presented with the above situation. Seven were immediately post-cardiopulmonary resuscitation and none had antecedent histories of abdominal pain or bilious vomiting. Abdominal radiographs could not rule out intra-abdominal pathology such as ischemic bowel. Review of all laboratory and radiological data showed US to be a discerning modality for acute bowel pathology. A characteristic pattern of echogenic ascites, thickened bowel wall, dilated, fluid-filled bowel lumen, and lack of peristalsis was seen in those children with gangrenous bowel. Sonographic examination accurately predicted the status of the bowel in all patients. Four patients survived: two had segmental ileal necrosis, one had localized gangrene of the jejunum (twice), and one had necrotic bowel from a closed-loop obstruction. The four who died had malrotation with volvulus (two), superior mesenteric venous thrombosis, and one was immunocompromised with pulmonary aspiration. We conclude that bedside US can be extremely valuable as an adjunct in assessing the abdomen and diagnosing gangrenous bowel in critically ill infants and children.