ABSTRACT
Cloacal anomalies are very rare congenital malformations with the incidence of 1/50,000-250,000 births. Hydrocolpos involves the dilatation of the vagina due to obstruction of the genital tract, leading to accumulation of secretions. Because of wide spectrum of abnormal anatomy involving urogenital and gastrointestinal systems, prenatal diagnosis is difficult. As ultrasound becomes more and more reliable, prenatal diagnosis is possible as early as in the second trimester. The presence of prenatally detected hydro (metro) colpos warrants a systematic evaluation of fetal and neonatal anatomy to rule out a large variety of possibly associated malformations or syndromes. We present a case of urogenital sinus maldevelopment which was initially presented as a fetal ascites.