Fluid retention between the walls of invaginated bowel in a 2-year-old boy who presented with intermittent irritable crying. Longitudinal US scan shows the short-segmental small bowel intussusception with entrapped fluid (arrows) between the intussuscepient and intussusceptum. Repeated US 1 hour later did not demonstrate the small bowel intussusception any more and the patient discharged with an improved state.