Posterior urethral valves: Role of prenatal diagnosis and long-term management of bladder function; a single center point of view and review of literature

Abstract

Posterior Urethral Valves (PUV) are the most common cause of lower urinary tract obstruction. More severe forms are detected early in pregnancy (mainly type I), while other forms are usually discovered later in childhood when investigating lower urinary tract symptoms. Bladder dysfunction is common and is associated with urinary incontinence in about 55% (0%-72%). Despite the removal of the obstruction by urethral valve ablation, pathological changes of the urinary tract can occur with progressive bladder dysfunction, which can cause deterioration of the upper urinary tract as well. For this reason, all children with PUV require long-term follow-up, always until puberty, and in many cases life-long. Therefore, management of PUV is not only limited to obstruction relief, but prevention and treatment of bladder dysfunction, based on urodynamic observations, is paramount. During time, urodynamic patterns may change from detrusor overactivity to decreased compliance/small capacity bladder, to myogenic failure (valve bladder). In the past, an aggressive surgical approach was performed in all patients, and valve resection was considered an emergency procedure. With the development of fetal surgery, vesico-amniotic shunting has been performed as well. Due to improvements of prenatal ultrasound, the presence of PUV is usually already suspected during pregnancy, and subsequent treatment should be performed in high-volume centers, with a multidisciplinary, more conservative approach. This is considered to be more effective and safer. Primary valve ablation is performed after clinical stability and is no longer considered an emergency procedure after birth. During childhood, a multidisciplinary approach (pediatric urologist, nephrologist, urotherapist) is recommended as well in all patients, to improve toilet training, using an advanced urotherapy program with medical treatments and urodynamic evaluations. The aim of this paper is to present our single center experience over 30 years.

Keywords: bladder function; bladder outlet obstruction; eUrogen; pediatric; posterior urethral valves; prenatal diagnosis; renal function; urodynamic.

Figure 1

Post-natal management of PUV. PUV, posterior urethral valves; RF, renal function; US, ultrasound; VCUG, voiding cystourethrogram; UTI, urinary tract infection; FU, follow-up; Cr, creatinine.

Figure 2

Voiding cistouretrography (VCUG) in newborn patient with posterior urethral valves with dilation of posterior urethra and vesico-ureteral reflux.

Figure 3

Pathophysiology of chronic kidney disease in posterior urethral valves. Posterior urethral valves (PUV) lead to obstructions of the urinary tract, with consequent impairment of kidney and bladder function development. Impairment in kidney development may result in hypodysplasia with a reduced nephron mass, and chronic kidney disease. Chronic kidney disease can progress to end-stage kidney disease. Lower urinary tract dysfunctionn can be aggravated by polyuria of the impaired kidneys and cause secondary vesicoureteral reflux and recurrent urinary tract infections. The latter may cause parenchymal scars in the hypodysplastic kidneys and accelerate renal failure progression.

Figure 4

General principles of CKD and bladder dysfunction treatment. Prenatal intervention (vesicoamniotic shunting, valve ablation via fetal cystoscopy, vesicostomy by open fetal surgery) yields no renal benefit. Since lower urinary tract dysfunction increases risks of developing chronic kidney disease, it should be treated. Urinary tract infections should be prevented (prophylaxis) and treated. Symptomatic secondary vesico-ureteral reflux, which persisted despite management of lower urinary tract dysfunction, should be treated preferably with endoscopic technique. CKD progression should be slowed down, treating symptoms and hypertension, n end-stage kidney disease, dialysis or preferably transplantation is necessary.