Isolated Fetal Ascites, Neonatal Outcome in 51 Cases Observed in a Tertiary Referral Center

Introduction Prenatal detection of isolated ascites is a rare finding on ultrasound, usually suggestive of an underlying pathology that may negatively impact on the pregnancy and neonatal outcome. The purpose of the present study was to evaluate the outcome of primary isolated ascites in relation to gestational age (GA) at diagnosis. Materials and Methods Data were prospectively collected for fetuses with ascites that have been followed in our center of prenatal diagnosis and therapy from 2004 to 2014. Patients have been divided in group I when ascites was detected before the 24th week of GA and group II if it was noticed later. Prenatal workup included detailed ultrasound, maternal blood group and presence of antibodies, maternal infection screening, fetal karyotyping, and if needed fetal paracentesis. Postnatal data included GA at birth, mode of delivery, weight at birth, neonatal and surgical outcome. Results During the study period, 51 fetuses were included. Among them, 28 in group I and 23 in group II. An associated anomaly was prenatally identified in 84% of the fetuses. Prenatal demise occurred only in patients belonging to group I for an overall incidence of 10%. An associated disease was confirmed after birth in 61% of cases in group I and in 74% in group II (p = ns). There was a higher incidence of gastrointestinal pathology in group II than in group I (47 vs. 10%, p = 0.004); with a significant prevalence of meconium peritonitis (32 vs. 4%, p = 0.016). Nine patients (17.6%) died after birth, all in group I, because of major systemic malformations. Overall, the postnatal outcome was good in 63% (n = 32) of the cases, and more than half of them belonged to group II (p = 0.003). Conclusion A wide range of etiologies have been found to be associated with isolated fetal ascites. A systematic diagnostic workup and multidisciplinary prenatal counseling can improve the accuracy of prenatal identification of associated pathologies. The early detection of fetal ascites, before the 24th week of GA, is associated with a significant risk of perinatal death; otherwise, a late diagnosis of fetal ascites is associated with an increased risk of gastrointestinal diseases, especially with meconium peritonitis.