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Posterior Urethral
Valves
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Posterior urethral valves are a congenital pair of obstructing
leaflets in the region of the verumontanum in the prostatic urethra.
The etiology is unclear, but they may form when the ventrolateral
folds of the urogenital sinus fail to regress. Obstruction from
urethral valves increases voiding pressures that result in dilatation
of the prostatic urethra, hypertrophy of the bladder neck, bladder trabeculation,
vesicoureteral reflux, renal dysplasia, and loss of renal function.
The degree of obstruction creates a spectrum of damage and, consequently,
a wide range of clinical presentations. Posterior urethral valves
(PUV) are the most common cause of lower urinary obstruction in
male infants and the most common type of obstructive uropathy leading
to childhood renal failure. The incidence of PUV is 1 in 5000 to 8000
male infants.
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Most infants with posterior urethral valves (PUV) are identified
with bilateral hydroureteronephrosis on prenatal ultrasonography.
The classical “keyhole” appearance on antenatal
sonographic evaluation is very suggestive of PUV and represents
the dilated posterior urethra (small hole) and the bladder (large
hole). Other causes of bilateral hydroureteronephrosis include prune
belly syndrome, vesicoureteral reflux, and bilateral ureterovesical
junction (UVJ) obstruction. After birth, the diagnosis is confirmed
with a voiding cystourethrogram (VCUG). If the diagnosis is not detected
on prenatal ultrasonography, the infant may present with a wide
range of signs and symptoms, including delayed voiding, a distended bladder,
palpable kidneys, a poor urinary stream with dribbling, or urosepsis.
Constitutional symptoms such as abdominal distension, failure to
thrive, and vomiting may occur. An infant may present with signs
of renal failure such as hyponatremia and hyperkalemia. Later in
childhood, nonspecific voiding problems such as incontinence, nocturnal
enuresis, frequency, and recurrent urinary tract infections may
result from PUV.
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Massive unilateral vesicoureteral reflux is a unique entity seen
in PUV patients and is termed valve, unilateral, reflux,
and dysplasia (VURD) syndrome.
Because of the pressure pop-off afforded by the refluxing kidney, the
contralateral kidney is protected, the ipsilateral side takes the brunt
of the increased voiding pressure, and patients with VURD syndrome
usually have a better prognosis in regard to end-stage renal function
when compared to children with a PUV presentation involving compromise
of both kidneys.
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Although the relief of obstruction in utero had theoretical benefit,
treatment trials have shown no long-term benefit.9,10 Treatment
of fetal-diagnosed posterior urethral valves (PUV) at birth is critical
to relieve the obstruction. Immediate stabilization of the baby
with bladder drainage is mandatory. It is preferable to insert a
6F feeding tube instead of a Foley catheter, as the tube lumen is
larger, and the lack of a balloon reduces bladder instability. Sepsis, electrolyte
abnormalities, acidemia, and fluid imbalance demand aggressive management. After
stabilization of the infant, primary transurethral valve ablation
is performed when technically feasible.10 If the
urethra is too small to accept an infant cystoscope, a temporary vesicostomy
may be performed. High diversion with loop ureterostomies is reserved
for infants whose renal function continues to deteriorate despite
bladder drainage; this condition is often indicative of intrinsically
poor renal development and future function. Older boys can almost
always undergo primary transurethral valve ablation because urethral
size is not an issue, and overall renal function is usually better
preserved.
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Long-term complications from PUV include the development of bladder
dysfunction and onset of renal insufficiency. Bladder dysfunction may
be manifest by detrusor instability and a small noncompliant bladder.
Some patients will develop the so-called “valve bladder” syndrome, which
is characterized by persistent hydroureteronephrosis in the absence
of an ureterovesical junction (UVJ) obstruction and is related to
a small-capacity, high-pressure bladder. Some patients can be managed
effectively with double voiding or anticholinergic medication and
clean intermittent catheterization. If bladder capacity and hydroureteronephrosis
do not improve, surgical bladder augmentation may be required. The incidence
of end-stage renal disease in PUV is approximately 25%.
A useful predictor of renal failure is the nadir serum creatinine
at 1 year of age. A serum creatinine < 0.8 g/dL after
the age of 1 makes renal failure less likely.11
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The prune belly syndrome is a complex consisting of congenital
absence or deficiency of abdominal wall musculature, bilateral cryptorchidism,
and anomalies of the urogenital tract, mainly, dilation of the prostatic
urethra, bladder, and ureters. The syndrome is also known as the triad
syndrome or the Eagle-Barrett syndrome.
It is believed to result from urethral obstruction early in development
that results in urinary ascites with degeneration of the abdominal
wall musculature, lack of pulmonary development, and failure of
testicular descent. Impaired passage of urine from the bladder leads
to oligohydramnios, pulmonary hypoplasia, and Potter facies.12 Female
patients cannot develop cryptorchidism and therefore have an incomplete
form of the phenotype and account for approximately 5% of
cases.
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The severity of pulmonary involvement and renal disease affects
outcome. Death in the perinatal period is more likely in the most
severe expression of the process with pulmonary hypoplasia, complete
urethral obstruction (without a patent urachus), and renal insufficiency.
Advances in neonatal intensive care have improved the survival for
some of these infants, but the prognosis remains poor. In newborns
with prune belly syndrome (and a patent urachus), the severity of pulmonary
hypoplasia is reduced due to the absence of urinary ascites. These
infants often have moderate to severe renal insufficiency and failure to
thrive. The clinical course is one of either renal stabilization
or progressive loss of renal function culminating in renal transplantation.
Those infants with prune belly syndrome and an absence or deficiency
of the abdominal musculature with undescended testes but normal
renal function despite an abnormal urinary tract comprise the majority
of children with prune belly syndrome, and they do not develop significant
renal impairment.
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Diagnosis and Management
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Often, diagnosis is made prenatally by ultrasound. The most obvious
defect in newborns with the syndrome is the rugated, prunelike appearance
of the abdominal wall, often with visible peristalsis of bowel loops.
As the child begins to stand, a pear-shaped or pot-bellied appearance occurs.
Evaluation for other anatomic abnormalities, pulmonary function,
and renal function is required to predict outcome. The weakness
of the abdominal musculature limits respiratory effort and may result
in developmental delay in motor activities associated with axial
balance. Recurrent respiratory infections and chronic constipation
occur due to an impaired cough and strain from the lack of abdominal
musculature.
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Abnormalities of the urinary tract are the major factors affecting
the prognosis of children with prune belly syndrome. Typical radiologic features
include elongated, tortuous, and dilated ureters that have poor
or absent peristalsis and a large-capacity, smooth-walled bladder
with a patent urachus. Vesicoureteral reflux (VUR) is present in
70% of cases. The posterior urethra is dilated, and the
prostate is absent or hypoplastic.
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Abnormalities in the epididymis, seminal vesicles, and vas deferens,
in addition to the bilateral cryptorchidism, may be responsible
for the infertility uniformly seen with this syndrome. The anterior
urethra is usually normal; however, abnormalities range from urethral
atresia to a fusiform or scaphoid megalourethra. Renal dysplasia
and multicystic dysplastic kidney (MCDK) are common, and the extent
of renal parenchymal involvement determines ultimate renal function.
Bilateral cryptorchidism is a consistent finding of prune belly
syndrome. The location of the testes is usually at the level of
the iliac vessels in an apparent intraperitoneal position on a long
mesorchium.
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Varied approaches to the management of prune belly syndrome have
been advocated, including trials of fetal therapy with combined vesicocentesis
and amnioinfusion, but these approaches are not yet validated.13The
goals of early management are to preserve renal function and pulmonary
health, as well as to prevent infection of both. Invasive procedures
may complicate treatment of urinary tract infections and should
be avoided if possible. Many infants require no early intervention.
The dilatation of the urinary tract in prune belly syndrome is usually
a low-pressure, nonobstructive system. However, if during the newborn
period, renal function deteriorates secondary to obstructive uropathy,
intervention may become warranted. Temporary urinary diversion with
a vesicostomy or cutaneous pyelostomy may be employed. More extensive reconstructive
surgery (reduction cystoplasty and excision of distal ureters with
tapering and reimplantation of the healthier upper portion of the
ureters into the bladder) may be performed in an effort to reduce
stasis and prevent urinary tract infections in carefully selected
older children. Early orchiopexy is advocated and may be performed
in conjunction with reconstructive surgery or at the time of an
abdominoplasty. Patients are usually placed on antibiotic prophylaxis
to prevent urinary tract infections.
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Epispadias-Exstrophy
Complex
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The epispadias-exstrophy complex is the result of a persistent
cloacal membrane that does not retract normally toward the perineum.
The persistent membrane prevents medial mesenchymal ingrowth, causing
the future abdominal wall to remain laterally placed. With dehiscence
of the cloacal membrane, the posterior wall of the bladder becomes
exposed to the exterior on the surface of the abdominal wall. Bladder
exstrophy is almost always accompanied by epispadias. Epispadias
alone results if persistence of the cloacal membrane occurs only
inferiorly.
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The most common anomaly in this complex is classic bladder exstrophy,
occurring in 1 in 30,000 to 40,000 births with a male preponderance.
The risk of recurrence in a given family is 1%. The typical
features include a defect in the abdominal wall from the umbilicus
inferiorly, with the bladder open and exposed to the exterior. The
bony pelvis is shallow and does not make a complete ring, resulting
in a widely spaced, externally rotated symphysis pubis. In boys,
the penis appears foreshortened and wider, with dorsal curvature
with an open urethral plate. In girls, the mons and clitoris are
bifid, and the entire urethra is open dorsally. In both sexes, the
reproductive organs are normal. Indirect hernias are common. The
abnormal anatomy of the puborectalis muscle can result in rectal
prolapse. The upper urinary tracts are usually normal; however,
anomalies of renal development and fusion can occur. Bilateral vesicoureteral
reflux (VUR) is almost universal.
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The goals of management of the exstrophy-epispadias complex include
closure of the bony pelvis (with or without osteotomies), closure
of the bladder plate, reconstruction of the urethra, closure of
the abdominal wall defect, preservation of renal function, and creation
of a functionally and cosmetically acceptable penis in boys, and mons
and clitoris in girls. The surgical management is usually staged,
with closure of the bladder performed in the first 72 hours, but
a one-stage technique, including bladder closure concomitant with
epispadias repair, can also be performed. Epispadias reconstruction
and penile lengthening are usually accomplished at 1 year of age
if the staged approach is chosen. The final stage of surgical reconstruction
involves bladder neck reconstruction for age-appropriate urinary incontinence
and ureteral reimplantation to correct vesicoureteral reflux, which
is performed at approximately 4 to 5 years of age, or when there is
adequate bladder capacity. Some groups have shown encouraging results
with reconstruction of the epispadiac penis and closure of the bladder in
a single stage. Despite successful bladder closure and epispadias
repair, some bladders fail to grow. In these cases, bladder augmentation
with a bowel segment and clean intermittent catheterization are
required. With a staged approach, success rates for spontaneous
voiding with urinary continence approach 75% to 85%.
As the complete primary repair of bladder exstrophy is still a relatively
recent technique, data on long-term follow-up for continence are
still accruing for these children.
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Anterior Urethral Anomalies
++
Urethrorrhagia occurs only in boys and consists of terminal hematuria
or spotting of blood on the underwear. It is often associated with
mild dysuria. Diagnosis is made by history and confirmed with a
normal physical examination. The urinalysis may show microscopic
hematuria but is often negative. Evaluation should include an ultrasound
of the kidneys and bladder to exclude any structural anomalies if
hematuria occurs. Cystoscopy is rarely indicated unless the symptoms
persist beyond 6 months or the history is inconsistent with the
diagnosis. The symptoms are usually intermittent and may last for
up to 1 year or longer, but more than 90% resolve by 2
years.14 Although this condition causes great concern
and anxiety in parents, the process is self-limited, and reassurance
and patience is the preferred approach.
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Complete eversion of the urethral mucosa through the external
meatus or urethral prolapse occurs almost exclusively in prepubertal
girls of African descent. The etiology of the prolapse is unclear
but may be related to an intrinsic anatomic defect involving the
periurethral smooth muscle layers in association with episodic increases
in intra-abdominal pressure. Predisposing factors include coughing,
constipation, trauma, and urinary and vaginal infections. Presenting
symptoms include vaginal bleeding or spotting on the child’s
underwear and sometimes mild dysuria.15 Physical
examination often demonstrates a typical-appearing everted, hemorrhagic,
donut-shaped periurethral mass. A prolapsed ureterocele or a vaginal rhabdomyosarcoma
must also be included in the differential diagnosis due to similar
presentation. Often, this entity is misdiagnosed, and concern for
sexual abuse is raised. Management includes conservative medical
treatment with reduction of the prolapse, sitz baths, and topical
antibiotics. Surgical resection of the prolapsed portion of the
urethra may be required after the acute inflammation has resolved.