Steve J. Hodges, MD
Anthony Atala, MD
BASICS
DESCRIPTION
• Congenital obstruction of the posterior urethra that can cause variable degrees of dysfunction of all segments of the urinary tract, including the bladder, ureters, and kidneys
• Urinary tract dysfunction can include
– Functional bladder disorders including increased bladder wall thickness, fibrosis, and hyperactivity that may progress to myopathy and poor function
– The bladder changes may affect the upper tracts by transmitting high pressure to the renal parenchyma, causing deterioration of renal function
– Patients may have congenital renal dysplasia
EPIDEMIOLOGY
Incidence/Prevalence
• Congenital disorder
• 1 in 4,000–7,500 live male births
• No racial predilection
• Most common cause of lower urinary tract obstruction in males
• Accounts for 16.8% of children with ESRD
• The prevalence is 1:2,400–1:8,000
RISK FACTORS
• No racial predilection
• Only affects males
Genetics
• This disorder is usually sporadic.
• Cases have been seen in twins and siblings suggesting a poorly understood genetic component.
PATHOPHYSIOLOGY
• Congenital mucosal membrane (fold/valve) in the posterior urethra
• Hugh H. Young Classification (1919)
– Type I: Folds that extend distally from the verumontanum to divide into 2 membranes that attach to the anterolateral wall, most common variant (95%)
– Type II: Folds extending from the verumontanum to the bladder neck superiorly, not clinically obstructing, only of historical significance
– Type III: Transverse membrane in the posterior urethra, has a central aperture, located distal to verumontanum, rare (5%)
ASSOCIATED CONDITIONS
• Renal dysplasia
• Bladder diverticula
• Ascites
• Urine extravasation
• Vesicoureteral reflux
• Azotemia
• Hydroureteronephrosis
• VURD
GENERAL PREVENTION
No known methods of prevention
ALERT
High risk of end-stage renal disease in urethral valve patients.
DIAGNOSIS
HISTORY
• Antenatally
– No specific questions in the maternal or family history aid in diagnosis
– Prenatal US usually demonstrates bilateral hydroureteronephrosis and thick walled bladder in males (+/– oligohydramnios)
• Postnatally
– Nature or strength of urinary stream is a poor predictor of valves, or severity of obstruction
– Failure to thrive may be seen
– Straining or grunting while voiding
– May present with symptoms indicative of sepsis in a neonate due to UTI
– Delayed presentation considered in any male with a chronic history of day and night urinary incontinence, UTI, and/or chronic polydipsia/polyuria
PHYSICAL EXAM
• Common neonatal presentation
– General: Palpably enlarged bladder, possible abdominal distention due to ascites
– Pulmonary: Pulmonary distress syndrome, pulmonary hypoplasia
– Musculoskelet al: Potter’s facies, limb deformities (in patients with severe oligohydramnios)
– Genitalia: Bulge in the penoscrotal junction during urination is a sign of anterior urethral valves
DIAGNOSTIC TESTS & INTERPRETATION
Lab
• Urinalysis and urine culture
• Serum electrolytes, BUN, and Cr
• Cr has early prognostic value
• Elevated Cr in 1st few days of life (after the 1st 5 days) indicates renal dysfunction and poor prognosis
• Cr >1 at the end of the 1st yr of life predictive of eventual ESRD
Imaging
• Renal/Bladder US
– Assesses for hydroureteronephrosis, corticomedullary differentiation, echogenicity, signs of renal dysplasia, thickness of renal parenchyma and bladder wall
• VCUG
– Diagnoses urethral valves, detects vesicoureteral reflux and bladder trabeculation diverticula
– Shows dilated posterior urethra, trabeculated bladder, vesicoureteral reflux, perhaps ascites
– Hydroureteronephrosis
• DMSA Renogram
– After 6 wk of life may be used to evaluate renal function, dysplasia
Diagnostic Procedures/Surgery
• Prenatal
– Antenatal US: Bilateral hydroureteronephrosis (+/– oligohydramnios, the earlier the diagnosis the worse the prognosis)
• Postnatal
– US, VCUG, laboratory evaluation
– Cystoscopy: Confirms the diagnosis of PUV by direct visualization of the obstructing valves
Pathologic Findings
N/A
DIFFERENTIAL DIAGNOSIS
• Anterior urethral valves
• Bilateral UPJ obstruction
• Congenital urethral polyp
• Congenital urethral stricture (Cobb collar)
• Megacystis-megaureter
• Megalourethra
• Multicystic dysplastic kidney
• Neuropathic bladder
• Nonneurogenic neurogenic bladder (Hinman syndrome)
• Plicae colliculi
– Normal anatomic finding
– Represents this folds of mucosa that extend from the verumontanum in the prostatic urethra to the membranous urethra
• Prune belly syndrome
• Urethral atresia
TREATMENT
GENERAL MEASURES
• Place urethral catheter immediately after birth to drain the bladder (1)
• Measure daily weights, I/O’s (fluid balance), routine vital signs
• Fluid and electrolytes as needed
MEDICATION
First Line
• Prophylactic antibiotics
– <2 mo age: Amoxicillin 20 mg/kg/d
– ≥2 mo of age: Trimethoprim-sulfamethoxazole 2 mg/kg/d (concentrates in urine); nitrofurantoin is an alternative
• Anticholinergics for bladder dysfunction
SURGERY/OTHER PROCEDURES
• Transurethral ablation of urethral valves is possible in 80% of neonates
• Cutaneous vesicostomy in children too small for endoscopy (usually <2,000 g)
• Bilateral cutaneous pyelostomies of mostly historical significance, but may be used in extreme cases
ADDITIONAL TREATMENT
Radiation Therapy
N/A
Additional Therapies
• Prenatal surgical intervention remains investigational
– Associated with risk of fet al and maternal morbidity; long-term renal benefit proven
• In children with persistent worsening renal function and hydroureteronephrosis following valve ablation may require upper tract diversion if possible to salvage renal function
• Persistent vesicoureteral reflux following valve ablation may require vesicoureteral reflux
• Low compliance fibrotic bladder or myogenic failure (valve bladder) may require enterocystoplasty and/or clean intermittent catheterization (CIC)
Complementary & Alternative Therapies
• Behavioral measures
– Timed voiding, constipation therapy
• Biofeedback
– Physical therapy to relax external sphincter
• Diet
– Avoid bladder irritant, caffeine
• Perineal hygiene
– Voiding positioning
ONGOING CARE
PROGNOSIS
• Depends on the amount of congenital renal dysplasia, vesicoureteral reflux, bladder function
• Incontinence and later ESRD correlated
• Cr >1 mg/dL at the end of the 1st yr of life correlated with ESRD
• Long-term bladder dysfunction may progress to overactive/fibrotic bladder or possibly eventual myogenic failure
• Sexual function and fertility seems to be normal in most patients
COMPLICATIONS
• End-stage renal disease
• Voiding dysfunction
• Incontinence
FOLLOW-UP
Patient Monitoring
• Follow-up for observation of progress of renal function, as high risk of ESRD
– Usual late or difficulty toilet training; treat voiding dysfunction, incontinence
– Patients need serial electrolyte and Cr measurements, US evaluations, VCUG following ablation to monitor success of surgery, resolution of reflux
– UDS for bladder function
– Prophylactic antibiotics as needed
Patient Resources
http://www.chop.edu/healthinfo/posterior-urethral-valves-puv.html
REFERENCE
1. Hodges SJ, Patel B, McLorie G, et al. Posterior urethral valves. Scientific World Journal. 2009;9:1119–1126.
ADDITIONAL READING
• Heikkilä J, Holmberg C, Kyllönen L, et al. Long-term risk of end stage renal disease in patients with posterior urethral valves. J Urol. 2011;186(6):2392–2396.
• Taskinen S, Heikkilä J, Rintala R. Effects of posterior urethral valves on long-term bladder and sexual function. Nat Rev Urol. 2012;9(12):699–706.
See Also (Topic, Algorithm, Media)
• Anterior Urethral Valves
• Bladder Outlet Obstruction
• Hydronephrosis/Hydroureteronephrosis, (Dilated Ureter/Renal Pelvis), Pediatric Incontinence, Pediatric
• Hydronephrosis/Hydroureteronephrosis, (Dilated Ureter/Renal Pelvis), Prenatal
• Posterior Urethral Valves Image 
• Urethra, Obstruction
• VURD Syndrome
CODES
ICD9
• 599.69 Urinary obstruction, not elsewhere classified
• 753.8 Other specified anomalies of bladder and urethra
• 753.15 Renal dysplasia
ICD10
• N13.8 Other obstructive and reflux uropathy
• Q61.4 Renal dysplasia
• Q64.79 Other congenital malformations of bladder and urethra
CLINICAL/SURGICAL PEARLS
• No benefit to early delivery as children with pulmonary hypoplasia also have severe renal dysplasia.
• Select centers offer prenatal interventions with dubious efficacy.
• Poor kidney function at presentation is associated with worse renal prognosis.