A 19-MONTH-OLD boy presented with a 5-day history of fever (temperature, 40°C), a 4-day history of nonbilious vomiting and small-volume, orangish mucoid stools, and a 1 -day history of abdominal pain. He was in moderate distress, guarding his abdomen. Abdominal examination revealed a soft but tender abdomen with significant guarding, especially from the right lower quadrant to the midline, where there was fullness. Rectal examination revealed no stool in the rectal vault or bowel wall tenderness.
There was a paucity of air on an abdominal roentgenogram. An abdominal ultrasound study showed a 3×5-cm mass (Figure 1).
Results of the laboratory evaluation were significant for a white blood cell count of 41.7 ×109/L, with 6% bands and 69% polymorphonuclear cells. The C-reactive protein level was 12.8 mg/dL (normal, <0.8 mg/dL).
Due to the acute nature of the results of his abdominal examination, the ultrasound findings, and the elevated white