Green Vaginal Discharge in a Late-Preterm Neonate With Massive Ascites

A late-preterm girl (35 + 1 weeks; birth weight 2440 g) was born after preterm labor in the setting of meconium-stained amniotic fluid and a tight body cord. At birth, she presented with abdominal distension and right upper quadrant ecchymosis. Within hours, she developed progressive respiratory distress requiring escalation from continuous positive airway pressure to intubation in the setting of worsening abdominal distension. Gastric decompression yielded bilious fluid, and she was started on intravenous fluids and antibiotics. Initial radiographs demonstrated paucity of bowel gas without pneumoperitoneum or calcifications. After transfer to a tertiary neonatal intensive care unit for suspected intra-abdominal pathology, she was pale with sluggish capillary refill and had a tense, distended abdomen with absent bowel sounds. Laboratory evaluation revealed anemia and coagulopathy, and abdominal ultrasonography demonstrated massive ascites with internal debris and abnormal hepatic venous flow. Despite stabilization, abdominal distension progressed over several days. On day of life 4, thin dark-green fluid drained from the vaginal introitus in the setting of otherwise normal external genitalia and anorectal anatomy. What is the most likely diagnosis?