Idiopathic fetal ascites: A case report

Background Fetal ascites is usually detected in the context of hydrops. Isolated ascites, as defined by effusions only in the peritoneal cavity, without involvement of of the skin or other cavities, is uncommon and its pathophysiology unclear. Once isolated ascites has been diagnosed, a detailed sonogram through a specialist should rule out other structural anomalies (most commonly gastrointestinal, genitourinary or cardiac). Furthermore testing to rule out genetic conditions and intrauterine infections is needed. Once these ethologies have been ruled out, the rare(~4%) diagnosis of idiopathic ascites, without an identifiable cause and usually transient in nature (resolving pre- or postnatally) can be set.

Methods A 34-year-old primigravida was referred to our center with fetal ascites at 21+3 weeks. A detailed anatomy scan confirmed an isolated ascites, ruling out fetal anemia and other malformations. Drainage of the fetal ascites was performed on the same day. Genetic analysis as well as serologies for intrauterine infections were all normal.

Results Because of recurrent tense ascites within 6 days, a peritoneal-amniotic shunt was placed. This led to transient oligohydramnion over 5 days, most likely as the result of self resolving iatrogenic PPROM. The shunt was dislocated after 4 weeks with recurrent ascites. The parents decided to proceed with repeated drainage of the ascites. In total 4 further drainages were required. The last was performed at 37+1 weeks, followed by induction of labor and vaginal delivery of a healthy girl at 37+3 weeks. Postnatally the neonate showed minimal ascites, which resolved spontaneously over time.

Conclusion This case shows how the management of a case with fetal ascites in a center specialised in fetal diagnostics and intrauterine procedures can lead to the correct diagnosis of idiopathic ascites. This allows for appropriate management until the birth of a healthy term neonate requiring no procedures postnatally and avoiding unnecessary terminations or preterm deliveries

 

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Publication History

Article published online:
16 October 2025