RESUMEN
The aetiology of urinary tract obstructions (LUTO) is heterogeneous. The most common entities are isolated posterior urethral valves or urethral atresia in male foetuses. In female foetuses LUTO is frequently a part of complex malformations. The natural history of LUTO is characterised by high morbidity and mortality due to the development of severe pulmonary hypoplasia caused by oligo- or anhydramnios affecting the cannalicular phase (16-24 weeks of gestation) of pulmonary development. The degree of renal damage is variable and ranges from mild renal impairment in infancy to end-stage renal insufficiency, necessitating dialysis and transplantation. Foetal interventions in order to bypass the obstruction are biologically plausible and technically feasible. Vesico-amniotic shunting as well as (currently less frequent) foetoscopic cystoscopy and laser ablation of posterior urethral valves are minimally invasive treatment options. Previous reports indicate that prenatal therapy is suitable to reduce perinatal mortality but does not improve postnatal renal function. Selection of foetuses who may profit from prenatal intervention is aggravated by the lack of reliable prognostic criteria for the prediction of postnatal renal function in both ultrasound and foetal urine analysis. Furthermore, there is no randomised trial available at the time of writing. Because of a relevant complication rate and still no clear evidence for foetal benefit, interventions should be performed in specialised centres. Further studies are necessary to improve case selection of affected foetuses and to evaluate the impact of interventions in earlier gestational weeks. The data from the PLUTO trial (percutaneous shunting in lower urinary tract obstruction) conducted by the University of Birmingham may help to answer these questions. In the meantime selection of foetuses for prenatal intervention puts high requirements on interdisciplinary counselling in every case. A general treatment algorithm for foetal therapy is not available at the moment.