<s>[INST] context: A (Necrotising enterocollitis) IntussusceptionNelson 18th/1569-70Correlation with prior or concurrent respiratory adenovirus (type C) infection has been noted & the condition may complicates otitis media,gastroenteritis. Henoch-schonlein purpura or upper respiratory tract infection -Nelson 18th/ 1569It is postulated that gastrointestinal infection or the introduction of new food protein result in swollen peyer pateches in the terminal ileum & which lead to mucosal prolapse of the ileum into the colon, thus causing an intussusception.Stools of normal appearance may be evacuated in the first few hours of symptoms. After this time, fecal excretions are small or more often do not occur & little or no flatus is passed. Blood is generally passed in the 1st 12 hr, but at times not for 1-2 days, & infrequently not at all; 60% of infants pass a stool containing red blood & mucus, the currant jelly stool.The presence of bloody mucus on the finger as it is withdrawn after rectal examination supports the diagnosis of intussusception.Necrotising Enterocolitis (NEC): Nelson 18th/755The onset of NEC usually occur in the 1st 2wk of life but can be as late as 3 month of age.The first signs of impending disease may be nonspecific including lethargy & temperature instability or related to gastro intestinal pathology such as abdominal distention & gastric retention. Obvious bloody stools are seen in 25% of patient.Almost all patients of NEC are artificially fed prior to the onset of illness. Breast milk is protective. (O.P. Ghai 6th/164)Mucosal injury in intestine is attributed to ischemic damage due to fetal distress, perinatal asphyxia, respiratory'distress syndrome, hypothermia etc.Meckel's Diverticulum (Love & Bailey 25th/83)A meckel's diverticulum is a remnant of the vitelline duct that is located about 60 cm proximal to the ileocaecal valve & is present in about 2% of individual.It may cause peptic ulceration & profuse (relatively painless) dark red rectal bleeding.This disease has no association with respiratory infection or top feeding.Volvulus [Nelson 18th/ 1557)Gastric volvulus is a triad of sudden onset of severe epigastric pain intractable rectching with emesis & inability to pass a tube into the stomach.The clinical presentation of gastric volvulus is non specific & suggest high intestinal obstruction. [/INST] question: A infant on top feeding develops distension of abdomen & bleeding per rectum. He recently recovered from acute upper respiratory tract infection. What is probable diagnosis: | options: A: Necrotising entero collitis B: Volvulus C: Meckel's diverticulum D: Intussusception | answer: A </s>