Pressure-limited vesico-amniotic shunt tube for fetal obstructive uropathy

IntroductionIn utero shunting (vesico-amniotic shunt) of obstructive uropathy in fetal lambs produces a shrunken, noncompliant bladder. We hypothesized that using a ventriculo-peritoneal shunt for the vesico-amniotic shunt may preserve the filling/emptying cycle and thus normal bladder development.Materials and MethodsWe created obstructive uropathy in 60-day gestation fetal lambs, ligating the urethra and urachus. Vesico-amniotic shunting was performed 21 days later using the valve end of a ventriculo-peritoneal shunt (valve shunt) or silastic tubing (nonvalve shunt). They were delivered at term (145 days), and the bladder volume was measured and compared to normal term fetuses. The lambs were sacrificed, and the kidneys and bladder removed for histology.ResultsTwenty-seven lambs were shunted. Of 14 valve shunts, 8 were effective. Of 13 nonvalve shunts, 11 were effective. The mean bladder volume was 57 ± 41 mL with a valve shunt and 8.8 ± 4.7 mL with a nonvalve shunt (P < .05) (normal term lambs, 65 ± 18 mL, n = 5). Histology of the shunted bladders showed increased fibrosis in the submucosal and muscle layers. This was less obvious in lambs with a valve shunt.ConclusionA pressure controlled shunt for fetal obstructive uropathy improves bladder volume but does not prevent bladder wall fibrosis.