Approximately 4000 newborns (NB) per year develop NEC in USA. NEC is difficult to diagnose accurately early in its course because early signs are neither specific nor sensitive. Therefore, many NB suffer serious consequences due to late diagnosis and many others are treated unnecessarily because of suspected but never proven NEC. Because NEC alters the mucosal integrity of the GI tract, differences in GI absorption of an inert substance may be of value to differentiate early those NB who really have NEC from those who don't. IOH (Omnipaque, an iodine containing inert substance poorly absorbed by the normal GI tract) was found to be readily absorbed in an animal model of ischemic bowel disease. The purpose of this controlled, blinded study was to determine if CT scan counts of IOH concentration in urine samples, as a measure of GI absorption of IOH, is a useful test for early diagnosis of NEC. NB with and early clinical suspicion of NEC were eligible for the study (Group I). NB without suspicion of NEC who need a GI contrast study (GE reflux, GI obstruction) served as controls (Group II). Exclusion criteria were: renal failure, shock or definitive NEC. IOH (at 255 mOsm) was given by gastric infusion at 8 ml/kg when NEC was suspected. Urine was collected for 8 hs and then scanned by CT (Imatron Cine CT Scanner). NB's X-rays and clinical data were collected prospectively. NB's in group I were subdivided in two subgroups(I-NEC and I-NO NEC) according to final diagnosis made by classic criteria. The M.D.performing CT counts was blinded to group assignement and final diagnosis; clinical teams were unaware of CT counts. We studied 22 NB, 15 in Group I (7 inI-NEC; 8 in I-NO NEC) and 7 in group II. No side effects were found. NB in I-NEC had mean urine CT counts of 71(±12); all had a CT count >55. CT counts were 15(±9) inI-NO NEC and 11(±7) in Group II; all had counts <30. We conclude that this test is of value for ruling out or confirming early the diagnosis of NEC. Supported in part by NIH, MO1RRO1271