RESUMEN
Vaginal bleeding of the newborn is described as a normal phenomenon, occurring physiologically in a subset of baby girls as a response to decreased oestrogen levels in the postnatal period compared with in utero exposure. Here, we present the case of heavy vaginal bleeding prompting an evaluation via transabdominal ultrasound, which was ultimately diagnostic for uterus didelphys. We suggest that neonates with uterus didelphys are predisposed to heavy bleeding due to relatively larger amount of the endometrial tissue in two cavities. While diagnosis of Müllerian anomalies is typically made in adulthood, an earlier diagnosis facilitates timely medical and surgical intervention and prompts screening for concurrent and associated conditions. In summary, we recommend routine consideration of transabdominal ultrasound to investigate abnormal vaginal bleeding in the newborn.