Current trends in the management of posterior urethral valves in the pediatric population.

P urethral valves (PUVs) are the most common congenital abnormalities causing bilateral renal obstruction. The widespread use of prenatal ultrasonography has contributed to an increase in the incidence and awareness of PUVs. The treatment of children with this anomaly has also evolved as radiographic imaging techniques and our understanding of the pathophysiology of obstructive uropathy has improved. Today, patients with PUVs who develop end-stage renal disease have the hope of undergoing renal transplantation; patients with PUVs represent 1% of those awaiting transplantation.1 Urodynamic investigation has allowed us to treat incontinence secondary to associated bladder dysfunction effectively, and the development of smaller endoscopic instruments and newer valve ablation devices have helped minimize perioperative morbidity. The mortality rate associated with PUVs has declined from 50% in the past few decades to less than 5%.2 Renal hemodialysis, excellent broadspectrum antibiotics, and improvements in neonatal intensive care units have contributed equally to the decline in mortality. According to Walker and Padron,3 mortality from PUVs usually occurs in newborns with severe bilateral renal dysplasia and pulmonary hypoplasia who were stillborn or died shortly after birth, neonates who died of sepsis or electrolyte imbalances, or older children and adolescents who eventually had renal failure. Despite these advances, 24% to 45% of patients will have renal insufficiency during childhood.4–7 Unfortunately, prenatal diagnosis of PUVs has not improved this rate. PUVS are encountered most commonly in males; however, anecdotal cases have been reported in females. Urethral valves have a wide range of clinical and anatomic presentations. Although most patients are diagnosed in the prenatal and neonatal period, published reports regarding patients presenting in adolescence and the second decade of life lends credence to the idea that PUVs may be a spectrum of disease as suggested by Hendren8 in 1971. The incidence is estimated to be between 1:3000 and 1:8000.1–8 Everyone agrees that to salvage renal function and maximize growth in infants with PUVs, obstruction of the urinary tract should be relieved at the earliest gestational age possible. Some believe that prenatal intervention is warranted if pulmonary hypoplasia or postnatal pulmonary insufficiency is to be avoided. Although controversial, prenatal intervention is technically difficult, and the ethical dilemma associated with it precludes its use in many surgical centers worldwide. PUVs can be associated with hypospadias, ureteropelvic junction stenosis, imperforate anus, dysgenetic kidneys, double urethra, solitary kidney, crossed renal ectopia, congenital heart disease, and arguably, prune belly syndrome. Three types of valves were described by Young and associates9 in 1919. Type I valves originate distal to the verumontanum on the floor of the posterior urethra. The valve cusps diverge distally in an anterolateral orientation and fuse anteriorly in the midline. Type II valves are folds of tissue that run between the bladder neck and the verumontanum. Type III valves are located just distal to the verumontanum; they are often characterized by a diaphragm-like appearance with an opening located posteriorly. Type I valves remain the most common type, and type III valves are very rare. The true incidence of type II valves is not known because most of these patients are asymptomatic, and some investigators doubt their existence. Dewan10 has advocated the presence of a common congenital posterior urethral obstruction morphology and termed this entity congenital obstructive posterior urethral membrane. This clinical observation sugFrom the Division of Urology, Department of Surgery, Creighton University, Omaha, Nebraska; Division of Pediatric Urology, New York Hospital-Cornell, New York, New York; and Divison of Pediatric Urology, Schneider Children’s Hospital, Long Island Jewish Medical Center, New Hyde Park, New York Reprint requests: Paulos Yohannes, M.D., Division of Urology, Department of Surgery, Creighton University, 601 North 30th Street, Suite 3822, Omaha, NE 68131 Submitted: October 22, 2001, accepted (with revisions): February 5, 2002 REVIEW CME ARTICLE