A premature neonate on top feeding develop abdominal destension and bleeding per rectum. He recently recovered from acute upper respiratory tract infection. What is the probable diagnosis

.Necrotising enterocoilitis occurs among premature infants under stress in first week of life. pathogenesis:mucosal injury, bacterial infections of the injured gut with E.colli,,Klebsiella,Pseudomonas ,Clostridia, Salmonella,formula feeding clinical features: stage 1:unstable temperature,apnea,lethargy,mild abdominal distension,vomiting, in stage 1B ,blood is present in stools stage 2:clinical signs as above,bowel sounds are diminished,tenderness may be present.In 2B there may be metabolic acidosis and thrombocytopenia. Stage 3:above features+low BP,bradycardia,apnea,acidosis,DIC,even anuria ESSENTIAL PEDIATRICS,O.P.GHAI,PG NO:139, 7th edition