Etiopathogenesis, evaluation & Mx of PUV

Dr. Shubham Lavania

20/05/2016

Introduction

• A congenital obstruction of the posterior urethra ascribed to valvelike leaflets

– 1769 by Morgagni

– Langenbeck in 1802

– Hugh Hampton Young coined “posterior urethral valve”(1919)

– Randall carried out the first endoscopic resection of valves in 1920

Incidence

• The most common structural cause of urinary

outflow obstruction in pediatric practice

• The most common type of obstructive uropathy

leading to childhood renal failure

• 1 of every 5000 to 8000 male births

• 10% of prenatally diagnosed hydronephrosis

• 1 PUV in 1250 fetal ultrasound

CLASSIFICATION

• Young classification 1919

PUV Defined

• Type I– Obstructing membrane that extends distally from each

side of the verumontanum towards the membranous urethra where they fuse anteriorly

• Type II– Described as folds extending cephalad from the

verumontanum to the bladder neck

• Type III– Represent a diaphragm or ring-like membrane with a

central aperture just distal to the verumontanum– Thought to represent incomplete dissolution of the

urogenital membrane

95% 5%

more serious

Type 1 PUV

• Develop when the mesonephric ducts enter the cloaca more anteriorly than normal.

Type 3 PUV

• Incomplete dissolution of the urogenital membrane

Pathophysiology

Primitive tissues mature in an abnormal environment of high intraluminal pressures and organ distention

• UNIVERSAL INJURY

IN THE URINARY

TRACT

Renal Dysplasia

• Defined as a congenital defect of tissue development without premalignant potential

• Histological diagnosis

• Cause ? 1- high pelvic pressure during

nephrogenesis2- primary embryologic abnormality

from abnormal position of uteteric bud

Renal Function

• Children with PUV may demonstrate gradual loss of renal function over time

• Cause:1- Renal parenchymal dysplasia2- Incomplete relief of obstruction3-parenchymal injury from :* UTI*HTN*Progressive glomerulosclerosis

from hyperfiltration* Obstruction

• ESRD

-Occurs in 25% - 40%

-1/3 soon after birth

-2/3 during late teenager

Renal Tubular Function

• 50% of patients with PUV have impairment concentration ability

• Persistently high urinary flow rate regardless of fluid intake or state of hydration

• severe dehydration and electrolyte imbalance

• ureteral dilatation and high resting vesicalpressure

Hydronephrosis

• Significant urethral obstruction variable degree of ureteral dilatation

• After relief of obstruction : gradual but substantial reduction of hydronephrosis

• If not reduced we have to role out:1- High intravesical pressure 2- ureteral muscle weakness 3- UVJ obstruction

Vesicoureteral Reflux

• Present in 33 - 50%

• Usually Secondary

– High intravesical pressures

• 33% resolve spontaneously when obstruction treated

• 33% do well on prophylactic antibiotics

BLADDER DYSFUNCTION

• Commonly presented in patient with PUV

• Usually primary, secondary to irreversible

change in organization and function of the

smooth muscle from outlet obstruction

• Present as urinary incontinence (20%)

• Bladder dysfunction persist in 75 % after valve

ablation

• May cause deterioration of renal function

• Three groups of dysfunction were described

- Detrusor –hyperreflexia (29%)

- Hypertonic and poor compliant bladder

(31%)

- Myogenic failure and overflow

incontinence (40%)

Valve Bladder Syndrome

• The term valve bladder syndrome was coined by Mitchell in 1982

• Factors responsible for devolution of a bladder into a valve bladder

(1) polyuria.

(2) poor bladder compliance with high-pressure voiding and elevated wall tension bladder, and

(3) residual urine volume.

Clinical Presentation

• Varies by degree of obstruction

– Symptoms vary by age of presentation

• Antenatal

– Bilateral hydronephrosis

– Distended and thickened bladder

– Dilated prostatic urethra

– Oligohydramnios - accounts for co-presentation of pulmonary hypoplasia.

Clinical Presentation

• Newborn– Palpable abdominal mass

• Distended bladder, hydronephrotic kidney• Bladder may feel like a small walnut in the suprapubic area

– Ascites• 40% of time due to obstructive uropathy

– History of Oligohydramnios– Respiratory distress from pulmonary hypoplasia

• Severity often does not correlate with degree obstruction• Primary cause of death in newborns

Clinical Presentation

• Early Infancy– Dribbling / poor urinary stream– Urosepsis– Dehydration– Electrolyte abnormalities– Uremia– Failure to thrive; due to renal insufficiency

• Toddlers– Better renal function (less obstruction)– Febrile UTI– Voiding dysfunction – incontinence– Daytime incontinence may be the only symptom in boys with

less severe obstruction

Diagnosis

Ultrasonography

• 1 in 1250 ultrasound screenings

• pathognomonic u/s findings:

– thickened, dilated bladder along with bilateral

hydroureter and pelvocaliectasis

– Oligohydramnios

– dilated posterior urethra

Antenatal U/S

Voiding Cystourethrography• Gold standard for diagnosing PUV

• Typically showed :

• VUR in 50% of patients with PUV

• Normal MCUG exclude PUV

Functional assessment

• Radionuclide Renal Scan

– quantification of differential renal function, and cortical deficits

– DTPA OR MAG-3

– with urethral catheter in place Exclude obstruction and assess split renal

function

• Serum Creatinine

– After 48 hours the infant's baseline laboratory values may be monitored.

– nadir creatinine value at 1 year of age is considered an important diagnostic tool

Initial Management

• Bladder Drainage– A 5 or 8 Fr pediatric feeding tube is ideal

– A Foley catheter should not be used, due to the tendency of the balloon to occlude the ureteral orifice and cause a bladder spasm.• Secondary obstruction

– Broad spectrum antibiotic coverage

– Metabolic panel• Assess renal function and metabolic abnormalities

• Acidosis, hyperkalemia common problems

Surgical Intervention

• Valve ablation

• Vesicostomy

• Upper tract diversion

• Circumcision

• Nephroureterectomy

• Transurethral Valve Ablation

– Incise at 5, 7 & 12 o’clock positions via Pediatric resectoscope

• Avoid urethral sphincter

• Catheter drainage for 1-2 days

• VCUG at 2 months to ensure destruction of valves

• Regular U/S to evaluate resolution of hydronephrosis

• Transurethral Valve Ablation– Alternatively, 8F cystoscope with a Bugbee

electrode adjacent

– Insulated crochet hook (“Whitaker hook”)• When urethra too small to accommodate

cystoscope/Bugbee

Antegrade valve ablation

• Zaontz and Firlit

• advantage of avoidance of instrumentation to the small male distal urethra

Vesicostomy

• reserved for

– the very lowbirth-weight infant

– continued impaired renal function,

– high bladder urine volumes,

– and upper tract deterioration after valve ablation or urethral catheterization.

•key operative step in creation of the vesicostomy is to

ensure that the posterior wall of the bladder is taut

•accomplished by bringing the dome of the bladder to the

skin

Upper tract diversion

Circumcision

• Risk of UTI in children with PUV is 50% to 60%

• UTI can quickly progress to pyelonephritis and sepsis

• Circumcision reduces that risk of UTI by 83% to 92%,

• Strongly recommended as a prophylactic measure for any boy diagnosed with posterior urethral valves

Antenatal m/m

• Intervention when antenatal sonography detects evidence of

– oligohydramnios,

– a dilated bladder, and

– severe hydroureteronephrosis—without renal cortical cystic lesions—in a fetus with a normal karyotype

• Vesicoamniotic shunting to treat oligohydramnios offers potential ameliorative effects on pulmonary function

PROGNOSTIC FACTOR

• Good Factors

• Nadir creatinine < 0.8 mg/dl

• S. creatinine < 1 mg/dl

• Pop-off mechanism

• - massive unilateral reflux

• -Urinary Ascitis (urinoma)

• - Large bladder diverticulum

Bad Factors• Age• Delayed correction• GFR < 50 % of normal in infancy• VUR- Bil -----> 57 % mortality- Uni. -----> 17 %- Non -----> 9 %• Loss of cortico medullary junction• delayed incontinence beyond 5 years

Transplantation in PUV Patients

• The prevalence of end-stage renal disease in PUV- up to 50%

• Obstructive uropathy as the second most common cause for transplantation

• Mixed outcome after transplantation

• Transplantation into a valve-affected bladder may carry a higher risk of ureteral obstruction

• However, there is no increased risk of graft loss compared to controls

Quality of Life with PUV

• have lifetime repercussions

• long-term risk factors

– valve bladder

– erectile dysfunction and infertility

– Risk of urinary tract infections

– associated comorbidities of renal transplantation

• counseling, preparing, and treating valve patients as they reach adulthood

Conclusions:Posterior Urethral Valves

• Two PUV types, Type I the most common, Type III with a worse prognosis

• Prognosis improved with improved symptoms within 1 month of therapy or the presence of a “Pop-off” valve

• Drainage, antibiotics and correction of metabolic disturbances key to initial care

• VCUG, U/S and renal nuclear scan to evaluate• Majority managed by valve ablation• Long-term sequelae significant, primarily renal

disease