Introduction Prune-Belly syndrome (PBS) is characterised by abdominal wall absence/hypoplasia, urinary system anomalies, and bilateral undescended testicle triad. The incidence is one in 30,000–50,000 live births, and 95% of the cases are male. Herein, we introduced a preterm infant with atypical PBS presented with fetal urinary ascite, abdominal wall defect, and bilateral undescended testicle.

Case A male twin premature neonate was born 2800 gr (10–50p) at 34 weeks gestation by caesarean section due to preterm labour and fetal distress. His Apgar score is 6 and 8 at postnatal 1^st and 5^th minute. His parents were non-consanguineous. It was learned the presence of fetal ascite at 21^st gestational age. On physical examination, abdominal distension due to fluid, bilateral undescended testicle were detected; abdominal muscles could not be palpated; eye examination and hearing test were normal. The abdominal ultrasonography (US) of the patient showed diffuse ascites, hypoplasia of the abdominal wall muscles, and bilateral testes in the inguinal canal. On his abdominal magnetic resonance imaging, ascites was detected. Transfontanel US, portal vein doppler US and voiding cystourethrography were normal. Echocardiography revealed patent ductus arteriosus, ventricular and atrial septal defect. Pericardial effusion was not observed. There were no anomalies of extremities and vertebra on his radiograms. The patient’s karyotype (male, 46, XY), routine biochemical evaluation, ferritin levels, viral serologies (TORCH, parvovirus B19) and metabolic scans were normal. While urea and creatinine levels were 19 mg/dl and 0.49 mg/dl in the serum, their levels were 23 mg/dl, and 0,55 mg/dl in the ascite fluid evacuated by paracentesis so, ascite fluid was considered urinary ascite in this case. The patient was discharged at 21 days of age.

Conclusion Fetal urinary ascite may be seen even if there is no coexisting urinary anomaly in the cases with PBS.