Paediatricscommon
A 7-month-old previously well boy is brought to the emergency department after six hours of episodes of sudden inconsolable screaming during which he draws his knees up to his chest. Each episode lasts several minutes; he was playful between the first episodes but is now pale, quiet and drowsy between them. He has vomited twice (milk-coloured) and passed one loose stool containing blood-stained mucus. On examination he is afebrile, there is an ill-defined fullness in the right upper quadrant of the abdomen, the right lower quadrant feels comparatively empty, and the inguinal regions and scrotum are normal. Which one of the following is the most likely diagnosis?