Rectal bleeding in early infancy: a warning sign of necrotizing enterocolitis that should not be overlooked in high-risk infants

Rectal bleeding in infants younger than 3 months may arise from benign conditions but can also represent an early sign of necrotizing enterocolitis (NEC).

We aimed to describe etiology, management, and outcomes of rectal bleeding in early infancy.

We retrospectively analysed data from patients presenting with rectal bleeding between 2015 and 2024, collecting demographics, comorbidities, diagnostic work-up, treatments, recurrence, and outcomes.

Ninety-one infants were included, with a median age at onset of 20 days; 34 (37.4%) were preterm and 43 (47.3%) had congenital heart disease (CHD). NEC was the most frequent diagnosis (35.1%), followed by isolated rectal bleeding (IRB, 22.0%) and infectious gastroenteritis (16.5%). Among infants diagnosed with NEC, 25.0% required surgery; it occurred predominantly in those with CHD (25/32, 78.1%) and preterm infants (7/32, 21.9%). Stool pathogens were detected in 25.3% of cases. Bleeding recurrence occurred in 16.5% of infants. In-hospital mortality was 2.2%.

NEC is the leading cause of rectal bleeding in early infancy, followed by IRB. Although IRB is often benign, rectal bleeding should always prompt careful evaluation, particularly in high-risk infants such as those with CHD and those born preterm, in whom rectal bleeding may represent an early manifestation of NEC. Early recognition and close monitoring are essential to optimize outcomes.