Perinatal management of posterior urethral valves detected by prenatal ultrasonography

Abstract

(Purposes) Posterior urethral valves (PUV) are the most common cause of mechanical infravesical obstruction in children. It is emphasized that this disorder has broad spectrum of severity, and patients presenting signs and symptoms in neonates or early infancy are at high risks for renal failure. The clinical pictures changed dramatically with the introduction of prenatal diagnosis by ultrasonography (USG). We report on perinatal management of PUV detected by prenatal USG, especially stressing on the significance of early delivery in risky fetuses. (Patients and Method) From 1987 to 1996, we treated 6 patients with PUVs who had been detected by prenatal USG. Fetal hydronephrosis was noticed between 26 to 29 weeks of gestation. Oligohydramnios was apparent at the same weeks of the detection or 2 to 7 weeks later. Fetal conference including obstetrician, neonatologist, anesthesist and urologist was taken place to discuss the date and mode of delivery. Among the patients, 5 were induced early delivery around 30 weeks of gestation. After birth, serum Cr was monitored, and small feeding tube was placed in the urethra. Primary valve ablation was indicated in 4 patients whose Cr returned to near normal after the urethral drainage. One required upper tract diversion because of the continuous elevation of Cr levels. (Results) Of the patients, one died of respiratory failure from lung hypoplasia. Ventilation support was needed in 3 patients. The patient who required upper tract divesion went into ESRF when he was 6 months old. Except for this patient, renal function improved in 4 patients with nadir Cr levels between 0.4 mg/dl to 0.6 mg/dl. Transurethral valve ablation was done on 5 patient between 16th to 40th days after birth with the lowest body weight at operation of 1450 g. Cystometric studies in neonatal periods showed small capacity, and hypertonic bladder in all patients. Valve ablation and administration of anticholinergics improved bladder function. (Conclusion) Prenatal ultrasonography clearly demonstrate the pathological features of the fetus with PUVs. Because oligohydramnios started in the early 3rd trimester indicates acute renal failure of the fetus, early delivery followed by emergency treatment may salvage the most severe type of this entity.