The etiology of small and fresh rectal bleeding in not-sick neonates: should we initially suspect food protein-induced proctocolitis?

This study was performed to identify the cause and frequency of food protein-induced proctocolitis (FPIPC) in not-sick neonates with small and fresh rectal bleeding and to verify the effectiveness of oral food elimination and challenge test (ECT) as a diagnostic method of FPIPC. We prospectively analyzed neonates with small and fresh rectal bleeding who were clinically normal. We investigated age at symptom onset, feeding at onset of bleeding, the time of bleeding disappearance, stool smear and culture, endoscopic findings, and histopathologies in the biopsy specimens of 16 not-sick neonates. We performed food ECT in cases with over 4 days of persistent rectal bleeding in the absence of any other etiology. In 16 not-sick neonates with rectal bleeding, the median age at symptom onset was 8.5 (1–43) days. Endoscopic abnormalities were observed in all 16 patients, and in 10 cases satisfying the pathological guidelines for FPIPC, two (12.5 %) were confirmed as FPIPC by food ECT. In the other 14 (87.5 %) cases, rectal bleeding spontaneously disappeared after on average at 4 (1–8) days and thus was diagnosed as idiopathic neonatal transient colitis (INTC). Conclusions: FPIPC is rare as a cause of small and fresh rectal bleeding in not-sick newborns and most of cases proved to be INTC. Although clinical findings are suspected as its symptoms and histological results satisfy its diagnostic criteria, FPIPC should be carefully confirmed through food ECT.