Abnormality of posterior urethral valves is a common cause of obstructive uropathy during fetal life. The prognosis depends on the degree of oligohydramnios, with which posterior urethral valves are always associated; moreover, it is a factor that significantly affects the intrauterine development of the lungs as well as the severity of the kidney impairment. Nowadays, diagnosis is prenatally possible, which leads to early intrauterine treatment with urinary decongestion, thus prognosis is significantly improved. Nevertheless, chronic renal insufficiency occurs later to a significant number of neonates. In this paper, a case of a male fetus with posterior urethral valves manifested as fetal ascites after rupture of the urinary bladder wall, as well as bilateral hydronephrosis is described. The parents decided, after having been thoroughly counseled, to terminate the pregnancy due to the risk of severe chronic renal failure, based on amniotic fluid electrolyte tests.