Herlyn–Werner–Wunderlich syndrome with a protruding hymen over the vaginal introitus in a neonate

•Herlyn–Werner–Wunderlich syndrome is a rare, congenital Müllerian anomaly.•The trilogy is uterus didelphys, obstructed hemivagina, and ipsilateral renal agenesis.•Presentation is usually cyclical abdominal pain and a vaginal mass after menarche.•Resection of hymenal or vaginal septum at an early stage can relieve acute symptoms.