Routine fecal occult blood testing does not predict necrotizing enterocolitis in very low birth weight neonates

To determine sensitivity, specificity, predictive value of routine fecal occult blood (FOB) testing on the identification of Bell's Stage II or III necrotizing enterocolitis (NEC) in very low birth weight (VLBW) infants.

Retrospective medical record review of VLBW infants from 2012- 2013 evaluating FOB results and clinical and demographic risk factors. We determined predictive values of positive FOB testing within 48 hours of definite NEC diagnosis. We performed logistic regression analyses for predictors of NEC and for predictors of having positive FOB during NICU admission.

The incidence of NEC in our cohort of 203 infants was 3.9% (n = 8). None had positive FOB results within 48 hours of diagnosis, and only 12.5% had any positive FOB within 7 days. Sensitivity of positive FOB for predicting definite NEC = 0%, specificity = 34.4%, and positive predictive value = 0%. A majority of VLBWs (67.0%) had > one positive FOB result during their NICU course. On logistic regression, intrauterine growth restricted (IUGR) infants had significantly higher odds of both developing NEC and of having positive FOB. Positive FOB was not a significant predictor of NEC. Those with lower birth gestational ages had higher odds of positive FOB.

Positive FOB testing occurred in a majority of VLBW infants, with higher odds in the more preterm and IUGR. However, the sensitivity, specificity, and predictive value of routine FOB testing for identifying NEC were all very poor. Our data demonstrates that this test offers no advantages in the early diagnosis of NEC.