Histopathology and microbiology of isolated rectal bleeding in neonates: the so-called 'ecchymotic colitis'

Rectal bleeding in neonates is an alarming event which suggests a possible necrotizing enterocolitis (NEC) but is usually the only symptom of an unexplained colitis characterized endoscopically by ecchymotic mucosal lesions, the so-called 'ecchymotic colitis' (EC). We studied histologically and bacteriologically 18 infants (mean age: 18 days) presenting with rectal bleeding by systematic rectosigmoidoscopy and intestinal biopsies. The 18 infants were hospitalized. Prematurity was found in seven cases and an underlying condition in 14 cases (respiratory distress: six cases; infection: six cases; surgery: two cases). Histology showed a mild to moderate inflammation (10/12) of the mucosa with a prevalence of polymorphonuclear cells (8/10), frequent focal haemorrhages (11/12) and foci of pneumatosis (4/12). Numerous bacteria were seen in the mucus layer focally forming large clusters. Cultures of intestinal biopsies yielded exclusively Enterobacteriaceae species: Escherichia coli (seven cases), Klebsiella spp. (seven cases), and Enterobacter cloacae (three cases); four cases were sterile. Our study demonstrates that neonatal bleeding is associated with endoscopic and histological 'ecchymotic colitis' lesions and with a peculiar microbial flora of EBC strains. EC and necrotizing enterocolitis share similar features raising the question of the link between the two syndromes.