A 6-month-old baby presents with history of bloody diarrhea of 2 days duration with abdominal distension and on examination the baby screams, diagnosis is:

Discussing the options one by one: a. Intussusception The typical age group with sho history of bloody diarrhea and extreme tenderness on examination point towards intussusception b. HUS Sudden onset pallor, oliguria, edema, petechiae and lethargy; Usually there is history of severe gastroenteritis with blood stained stools but no severe pain abdomen c. Appendicitis Typically presents with right lower quadrant pain with/ without gastroenteritis. It is most common in older children, with peak incidence between the age of 12 and 18 year d. Ac. enterocolitis There is usually a history of fever, vomiting and colicky pain abdomen, usually associated with tenesmus