Posterior urethral valves are the main cause of fetal lower urinary tract obstruction (LUTO) with typical sonographic signs like urinary tract dilatation and reduction of amniotic fluid. LUTO is associated with a high rate of perinatal mortality and is the main cause of kidney failure in early childhood. In such cases vesico-amniotic shunting is a common but risky procedure of fetal surgery to prevent anhydramnion and lethal lung hypoplasia. This case report demonstrates that lung hypoplasia can be prevented by vesico-amniotic shunting of the fetal megacytis in the 23rd week of gestation in a fetus with lower urinary tract obstruction and anhydramnion. The prenatal measured concentration of cystatin C in the fetal urine correlated with the postnatal impaired kidney function. The indication and therapeutic benefit of vesico-amniotic shunting remain controversially discussed in the literature because until today there is no evidence for a reduction in perinatal or long-term morbidity due to early fetal kidney damage. The earlier ultrasound detection of LUTO during the first trimester of pregnancy proposes the possibility of earlier intervention and protection of nephrogenesis. First case studies about first trimester vesico-amniotic shunting have been published; the influence on the postnatal kidney function merits further well-structured investigation.