For fetuses at gestational age greater than 18 and less than 30 weeks, if oligohydramnios is present, investigation of fetal renal biochemistry is offered. In case of favorable fetal renal biochemistry, vesico-amniotic shunt is offered as a fetal therapeutic intervention. In case the fetal urinary biochemistry is considered not favorable, then we will repeat the urinary examination in 24 hours. If the fetal urinary biochemistry is still not favorable, we will repeat the examination for the last time (maximum of 3 times). If it is still not favorable, then fetal vesico-amniotic shunt is not offered. However, if a fetal urinary examination reveals improvement favorable urinary biochemistry), fetal vesico-amniotic shunting is considered. Prenatal follow-up and delivery follow the same algorithm described previously.