Massive idiopathic isolated fetal ascites

Fetal ascites is commonly associated with gastrointestinal and urinary malformation, anemia, infection and chromosomal anomalies. Idiopathic massive fetal ascites is rare. We report a case of a 33-year-old pregnant woman referred at 17 weeks after significant ascites were detected in the absence of structural anomalies. Fetal cardiac scan were normal and viral diagnostic assay were negative. By 28 weeks massive ascites was detected with no other signs of fetal hydrops. Fetal middle cerebral artery peak systolic velocity was elevated. Umbilical artery Doppler, fetal growth and amniotic fluid volume were normal. Fetal echocardiogram was normal. Amniocentesis was done with normal karyotype results. Despite the persistence of massive ascites, serial ultrasound scans showed reassuringly normal growth and umbilical artery Doppler with high values of middle cerebral artery peak systolic velocity. At 33 weeks gestation an emergency caesarean section was done due to acute fetal distress. A female newborn was obtained with normal values of hemoglobin at birth. Liver, bladder and hepato-portal vascular flow were normal. Ascites resolved completely by day 8 and the baby was discharged after 15 days.