A 6-month-old baby with H/O bloody diarrhoea of 2 days duration with abdominal distension and on examination the baby screams, diagnosis is –
Clinical features of intussusception

Sudden onset
Severe paroxysmal colicky pain that recurs at frequent intervals.
Pain is accompanied by straining efforts with legs and knees flexed and loud cries (screaming).
Lethargy
Blood and mucus produce a current jelly stool.
Reflex vomiting is an early sign.
In later stages, vomiting becomes bile stained.
Abdominal distension and tenderness develop as intestinal obstruction becomes more acute.
Tender sausage - shaped palpable mass in the right upper abdomen with its long axis cephalocaudal.
Occasionally intestine prolapses through the rectum.
Intussuscetion
HUS
Appendicitis
Ac. Enterocolitis