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112 Duplication Anomalies, Ureteroceles and Ectopic Ureters
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Figure 8.10 Examples of conventional open surgical options. There are many variations depend-
ing on the anatomy and function in the individual case. (a) “Simplied Approach” normal lower
moiety, non-functioning upper moiety. Upper pole heminephrectomy combined with excision
of ureter accessible through the same incision. Aspiration of residual upper pole ureteral stump.
(b) Pyelopyelostomy. Ureters anastomosed at the level of the kidney. Upper pole ureteral stump
aspirated and left in situ. Alternatively, both ureters can be anastomosed in the pelvis adjacent to
the bladder – ureterouretrostomy (see text). (c) Excision of ureterocele and reimplantation of both
duplex ureters in their common sheath. (d) Heminephroureterectomy with excision of ureterocele.
Denitive surgical treatment but a major operation requiring two incisions or a laparoscopicallly
assisted procedure.
Infrasphincteric
An upper pole heminephrectomy is sucient in
such cases because it removes the renal parenchyma responsible for excreting the small
amount of urine which eventually emerges from
the opening of the ectopic ureter to cause incontinence. It is not necessary to remove the ectopic
ureter – although it may be reasonable to do so if
the heminephrectomy is performed laparoscopically since this does not require any additional
incisions.
Ureteroureterostomy
Ureteroureterostomy or pyelo pyelostomy used
to be limited to the small proportion of cases in
which there was sucient function in the upper
pole to justify its conservation. However, these
techniques are being increasingly applied to cases
with a poorly functioning upper pole moiety.
In the technique of distal ureteroureterostomy
the upper pole ureter is anastomosed to the lower
pole ureter in the pelvis. Before performing this
procedure, however, it is important to conrm
Bilateral single ectopic ureters 113
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that there is no reux into the lower pole ureter.
If the VCUG demonstrates that reux is present
the alternative options are to perform ureterouretostomy in conjunction with an antireux procedure or, alternatively to reimplant both ureters
together in their common sheath.
Ureteral Clipping
is novel technique has been reported for the
management of symptomatic ectopic ureters
associated with a non-functioning upper moiety.
Using a laparoscopic approach the ectopic ureter
is visualized and then clipped (ligated) – thus preventing the passage the urine responsible for causing incontinence. Initial results in small numbers
of patients have been promising but follow up has
been relatively short and there are uncertainties
regarding the long-term outcome of the hydronephrosis which develops in the upper pole following occlusion of the ectopic (upper pole) ureter.
VESICOURETERAL REFLUX
rather than pyelonephritic scarring. e management consists of removing the poorly functioning
lower pole together with as much of the reuxing
lower pole ureter as possible without compromising the adjoining upper pole ureter.
BILATERAL SINGLE ECTOPIC
URETERS (FIGURE 8.11)
is is an extremely rare abnormality which
occurs mainly in females. A single ureter on each
side drains in an ectopic location in the proximal
urethra. e ureteral ectopia is accompanied by
congenital weakness of the bladder neck and striated sphincter and greatly reduced functional
capacity of the bladder. Both ureters are usually
e management of VUR in duplex systems is
mainly concerned with lower pole VUR in complete
duplication and follows a very similar approach to
the management of VUR in single systems – as
described in Chapter 6. However, the rate of spontaneous resolution is lower than in single systems.
For this reason, greater consideration should be
given to surgical intervention if the child is experiencing symptomatic urinary tract infections.
Endoscopic correction is a reasonable option
for low grades of VUR (particularly in partial
duplication) but success rates are lower than for
comparable grades in single systems. For moderate or high grade VUR ureteral reimplantation
is usually required. When performing ureteral
reimplantation, both ureters should be mobilized and reimplanted together in their common
sheath to avoid jeopardizing the vascularity of
both ureters. However, this may not always be
feasible if one of the two ureters is dilated and it is
necessary to perform ureteral tapering.
Extensive loss of function in the ipsilateral
lower moiety is usually due to congenital dysplasia
Figure 8.11 Intravenous urogram demonstrat-
ing bilateral single ectopic ureters. Both ureters
drain extravesically and the bladder is of small
capacity.
114 Duplication Anomalies, Ureteroceles and Ectopic Ureters
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dilated and there are varying degrees of renal
dysplasia. is anomaly typically presents with
continuous dribbling urinary incontinence in
childhood or, more rarely, with features of renal
impairment in infancy.
●
e primary treatment consists of reimplantation of the ectopic ureters into the bladder.
However, further procedures such as bladder
●
augmentation and sphincter enhancing surgery
are oen required. As a last resort to achieve continence it may be necessary to perform surgical
closure of the bladder neck closure combined
with a Mitrofano procedure.
Treatment should be individualized
according to the anatomy, function and
presentation of each case.
Ureteroceles can be treated by endoscopic incision but there is a relatively
high requirement for secondary surgery.
A range of open surgical options are
available. Uretero-ureterostomy is
being increasingly performed as an
alternative to heminephrectomy.
KEY POINTS
●
e anatomy of complete ureteral
duplication is described by the MeyerWei gart Law.
●
Partial duplication is relatively common and is not usually of clinical
signicance. Complete duplication is
rarer and more frequently gives rise to
clinical symptoms and morbidity.
●
e upper pole moiety of a complete
duplex system which is associated with
a ureterocele or ectopic ureter is oen
poorly functioning or dysplastic.
●
MR urography is a valuable investigation for demonstrating an “occult”
duplex system suspected of causing
urinary incontinence in a girl.
●
Vesicoureteral reux is the commonest complication aecting a lower pole
moiety.
●
ere is no single approach to the
management of upper tract duplication.
FURTHER READING
Fufezan O, Tatar S, Dee AM, Cramariuc R,
Asavoaie C, Cosarca M. Large spectrum of
complete urinary collecting system duplication exemplied by cases. Pictorial essay.
Med Ultrason. 2013;15:315–320.
HK Le, G Chiang. Current urology reports,
2018 - Springer long-term management of
ureterocele in duplex collecting systems:
reconstruction implications
JR Dillman, AT Trout, EA Smith. Abdominal
Radiology, 2016 – Springer MR urography
in children and adolescents: techniques and
clinical applications.
Malik RD, Pariser JJ, Gundeti MS. Outcomes in
pediatric robot-assisted laparoscopic heminephrectomy compared with contemporary
open and laparoscopic series. J Endourol.
2015;29:1346–1352.
Sander JC, Bilgutay AN, Stanasel I, Koh CJ,
Janzen N, Gonzales ET, et al. Outcomes of
endoscopic incision for the treatment of
ureterocele in children at a single institution.
J Urol. 2015;193:662–666.
Posterior Urethral Valves and Other
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Urethral Abnormalities
DIVYESH Y DESAI and PATRICK G DUFFY
Topics covered
9
Posterior urethral valves
Anatomy/pathophysiology
Presentation/investigation
Treatment
Prognosis
POSTERIOR URETHRAL VALVES
Introduction
Urethral obstruction in children is usually
congenital in origin – with posterior urethral
valves (PUV) being by far the commonest cause.
Posterior urethral valves give rise to changes in
the upper urinary tract which reect the severity and duration of bladder outow obstruction
in fetal life. Severe obstruction which has been
present from early gestation is associated with
varying degrees of congenital renal dysplasia,
which is the principal cause of renal insuciency
and chronic kidney disease (CKD) in PUV
patients. Long-term morbidity also includes
symptomatic bladder dysfunction which oen
Long-term management
Anterior urethral diverticulum
Urethral duplication
Other urethral pathology
persists despite successful treatment of the
valves themselves.
Posterior urethral valves carried a mortality rate of almost 100% during the early years
of the 20th century and remained as high as
50% until the 1950s. By contrast, the mortality reported in one recent series was only 0.3%.
However, this reduction in early mortality has
come at the expense of a greater proportion of the
surviving children suering from chronic renal
failure. Posterior urethral valves are conned to
males, in whom the incidence is of the order 1 in
4000–6000 live births. Although some familial
cases have been reported, including in siblings,
no established genetic predisposition has been
identied and PUV generally behaves as a sporadic anomaly.
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Anatomy
Hugh Hampton Young in 1919 described the
rst classication of posterior urethral valves
based on postmortem dissection studies. He
described three types, Type I being the commonest (95%) which consisted of co-apting leaflets with a proximal attachment to the distal
verumontanum extending through the region
of the external urethral sphincter to attach to
the anterior urethral wall. Type III valves are
uncommon (5%) and are best described as a
transverse perforated membrane in the bulbar
urethra with no attachment to the verumontanum. Type II valves, are described as leaets
that extend upwards from the verumontanum to
the anterior aspect of the posterior urethra. It is
unlikely that Type II valves constitute a genuine pathological entity and they are generally
regarded as being non-obstructive mucosal folds
of no clinical signicance.
Some authors have challenged Young’s classication which identied three distinct patterns
of valvular obstruction. Dewan and Ransley’s
anatomical and endoscopic studies point to a
single conguration comprising an obliquely
orientated congenital obstructive posterior urethral membrane (COPUM) with a variably sized
eccentric aperture located within it which arises
from the verumontanum and extends through
the region of the external urethral sphincter to
attach to the anterior urethral wall (Figure 9.1).
It has been argued that urethral instrumentation, including catheterisation, disrupts the
valve membrane in the midline to create the
appearance of two separate, side-by-side valve
leaets described as the classical Type I valves
by Young.
Pathophysiology
Posterior urethral valves are thought to originate
from abnormal interaction between the mesonephric ducts and the urogenital sinus around the
seventh week of gestation. Dilatation of the fetal
urinary tract secondary to obstruction caused by
PUV can detected on ultrasonography as early as
14 weeks gestation.
Figure 9.1 Endoscopic appearance of intact
valve membrane prior to endoscopic ablation.
Studies of experimentally induced fetal bladder outow obstruction in various animal models
have established the following:
●
Early outow obstruction leads to abnor-
malities in bladder wall components with an
increase in the collagen element, aberrant
innervation and renal dysplasia. e charac-
teristic histological features of renal dysplasia
include the persistence of primitive tubules
and the presence of abnormal mesenchymal
derivatives such as cartilage interspersed
between normal renal tissue.
●
Obstruction in later gestation results in the
typical features of chronic bladder out-
flow obstruction and raised intravesical
pressure, without the occurrence of renal
dysplasia.
●
Intrauterine intervention to relieve
experimentally induced obstruction in fetal
animal has been shown to result in resolution
of hydro-ureteronephrosis. is is accompa-
nied by reversal of the detrusor hypertrophy
and more normal innervation of bladder wall
muscle.
In man, the clinical features of PUV may be at
any point on a wide spectrum of pathology ranging from relatively mild obstructive changes to
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gross changes in the bladder and upper tracts
accompanied by severe renal dysplasia.
us, the long-term prognosis in an individual
with posterior urethral valves is determined by
a combination of abnormal development of the
urethra, bladder, kidneys and the ureters, and
secondary consequences of congenital outow
obstruction on the development and function of
bladder and the upper urinary tract.
e relative contribution made by these dierent factors to the long-term outcome for bladder
and renal function is oen dicult to determine,
and therefore predicting long-term outcomes
can be dicult. e urinary tracts of boys with
posterior urethral valves must therefore be monitored through childhood, adolescence and early
adulthood.
Presentation
The fetus
More than 80% of cases are detected on prenatal ultrasound. Although the underlying urethral
anomaly dates from the seventh to the ninth week
of gestation, dilatation of the urinary tract may
not develop until later in pregnancy. In 55% of
prenatally detected cases of PUV abnormal ultrasound ndings are visualised on routine maternal ultrasound scans performed between 16 and
20 weeks. In the remaining cases, the appearances of the fetal urinary tract are normal in the
second trimester, and the condition only becomes
apparent on scans performed in later pregnancy –
mainly for obstetric indications.
Functional outcome is closely linked to the
gestational age at which dilatation becomes
apparent, and studies have shown that when the
condition is detected at 16–20 weeks the prognosis is more likely to be poor, especially if oligohydramnios is present. Oligohydramnios is a
manifestation of fetal oliguria or anuria. In pregnancies which proceed to term, a severely aected
newborn infant may demonstrate features of
Potter’s syndrome (characteristic Potter’s facies
and skeletal “moulding” deformities) with death
supervening in the early neonatal period due to
pulmonary hypoplasia. Biochemical constituents of fetal urine such as sodium, calcium and
Table 9.1 Ultrasound features of posterior
urethral valves in the fetus
Male fetus
Bilateral upper tract dilatation
Persistently distended full bladder
Predictors of poor functional outcome and
early-onset renal failure
Detection before 24 weeks’ gestation
Bladder wall thickening
Echo-bright kidneys (renal dysplasia)
Oligohydramnios
b2-microglobulin have been studied as possible
predictive markers of renal function. However,
there is considerable overlap with normal values
and their prognostic sensitivity is less reliable
than information yielded by detailed evaluation
of the ultrasound appearances. In addition to
dilatation and renal dysplasia (bright kidneys),
predictive ndings may include pulmonary
hypoplasia, urinary ascites and perinephric urinomas (Ta ble 9.1). In cases where dilatation does
not develop until later in gestation, the prognosis
is generally good.
The neonate
When symptoms are present these usually relate
to bladder outow obstruction or, less commonly,
to clinical manifestations of impaired renal function. Clinical features of listlessness, poor feeding, irritability and failure to thrive are common.
e urinary stream, if witnessed, is usually poor.
e bladder is palpable in most instances; the
kidneys may also be palpated. Urinary ascites
is occasionally present and does not necessarily
denote a poor prognosis.
The infant
Presentation in infancy is generally with urinary
infection and in the majority of cases there are
no immediately obvious signs of PUV. Gramnegative sepsis and renal failure with gross
electrolyte disturbance were common forms of
presentation but with increasing detection by
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prenatal ultrasound and greater awareness of
the features of urinary infection in infants it has
become much less common for PUV to present
with sepsis than in the past. Chronically impaired
renal function is usually manifest as poor growth
and general failure to thrive.
The older child
Presentation may include manifestations of renal
failure such as growth retardation, urinary infections, haematuria or voiding symptoms (typically
prolonged voiding, rather than a poor urinary
stream). However, “late presenting” cases of
PUVs are oen at the milder end of the spectrum
of severity and may occasionally be diagnosed
during the investigation of diurnal or nocturnal
enuresis.
Investigations
Figure 9.3 Ultrasound illustrating the diagnostic
“keyhole sign.” Dilated (thick-walled) bladder
and dilated posterior urethra.
can be made with more certainty if these ndings
are also accompanied by dilatation of the posterior
urethra – the so-called “keyhole sign” (Figure 9.3).
Prenatal
e presence of posterior urethral valves can only
be inferred from the ultrasound appearances of
a distended fetal bladder and dilated upper tracts
(Figure 9.2). Alternative diagnoses include urethral
atresia (which is always lethal), prune-belly syndrome, megacystis–microcolon intestinal hypoperistalsis syndrome and high grade primary
vesicoureteric reux. However, the diagnosis of PUV
Figure 9.2 Prenatal ultrasound demonstrating
marked dilatation of both fetal kidneys and the
fetal bladder. The fetal spine and thorax are
clearly visible in both these longitudinal images.
Postnatal
Ultrasonography is the initial investigation.
Relevant ndings in the upper tracts may
include; dilatation (which is sometimes unilateral), perinephric urinoma (a rare occurrence)
and changes in the renal cortex denoting dysplasia (e.g. “echo bright” parenchyma and cysts).
Ultrasound appearances of the bladder include;
bladder wall thickening, trabeculation and sacculation. ere may or may not be residual urine
retained in the bladder. If voiding views can be
obtained, ultrasound may demonstrate dilatation of the posterior urethra.
Micturating cystourethrography (MCUG) provides the denitive diagnosis, with a range of ndings, as illustrated in Fig ures 9.4 –9.6. Vesicoureteric
reux is present in 40–60% of cases at the time of
initial evaluation and is unilateral in approximately
two-thirds of cases.
Initial assessment also includes measurement of electrolyte balance and renal function. It
should be noted, however, that serum creatinine
levels in the rst 48 hours of life are a reection
of maternal renal function and it is not until the
infant is a few days of age that the plasma creatinine becomes a reliable measure of his own renal
function.
Figure 9.4 Newborn infant: micturating cysto-
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urethrogram (MCU). Grossly dilated posterior
urethra, indentation by prominent bladder neck,
small trabeculated bladder.
Posterior urethral valves / Treatment 119
Figure 9.5 Newborn preterm infant, prenatal
diagnosis. Heavily trabeculated bladder with
diverticulum, prominent bladder neck and
demarcation between dilated posterior urethra
and non-dilated distal urethra at the site of the
valve membrane.
Treatment
The fetus
e rationale for fetal intervention is based on
the ndings of studies in experimental animals which indicated that obstructive renal
damage could be ameliorated by intrauterine
decompression of the obstructed fetal bladder.
However, the extent to which these experimental ndings can be applied to the clinical setting
in humans is debatable. Initially, fetal intervention in humans took the form of hysterotomy
and open fetal surgery but this was soon superseded by ultrasound guided insertion of a shunt
between the obstructed fetal bladder and amniotic cavity. (See Chapter 4) One metanalysis of
10 published studies identied a higher survival
rate in shunted fetuses and a higher percentage
Figure 9.6 MCU in a boy presenting in the
rst year of life with urinary infection. Smoothwalled non-trabeculated bladder, unilateral
grade IV reux.
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of infants with normal renal function at 6
months to 2 years of age. However, the results
of comparative studies are dicult to critically
assess because of dierences in selection criteria and other weakness of methodology. In the
United Kingdom the multicentre percutaneous
shunting in lower urinary tract obstruction
(PLUTO) trial was established with the aim of
evaluating and comparing survival rates and
outcomes for renal and bladder function following vesicoamniotic shunting. Although the trial
was discontinued because of inability to recruit
sucient numbers of subjects, preliminary data
did not appear to identify any signicant benet
for renal function.
Fetal cystoscopy and intrauterine valve ablation has been reported as an alternative to vesico
amniotic shunting and there is limited evidence
to suggest that this approach might that have a
higher early survival rate. However, it has only
been used on a very limited scale and no longterm results are available.
In summary, although the published results of
fetal intervention have generally been disappointing, vesico amniotic shunting may have a limited
role to play when used on a selective basis.
Termination of pregnancy is probably the
most common form of prenatal intervention,
particularly when severe dilatation and associated oligohydramnios are detected in early pregnancy. In these circumstances decompression of
the obstructed urinary tract is of little benet for
renal function, since irreversible renal dysplasia
is almost invariably present.
Elective preterm delivery can be regarded as
another form of intervention, but it is probably
of limited benet except in cases where there is
evidence of rapidly progressing late-onset dilatation. In deciding the optimum timing for elective early delivery the predicted benet for renal
function must be carefully balanced against
the risk of pulmonary immaturity in preterm
infants.
Regardless of the controversies surrounding
fetal intervention, there is a universal consensus
that prenatal diagnosis has proved benecial by
facilitating prompt postnatal treatment of PUVs
and a corresponding reduction in the risk of
severe sepsis and pyelonephritic renal damage.
The neonate
To minimise risks of metabolic disturbance and
urinary tract infection (UTI), the obstructed urinary tract should be decompressed promptly by
either urethral or suprapubic bladder catheter
drainage. Once this has been achieved, there is no
compelling urgency to proceed to denitive treatment of the posterior urethral valves. Plasma biochemistry should be monitored during the rst
7–21 days to obtain a measurement of baseline
renal function (nadir creatinine) which serves as
a reasonably reliable predictor of the later functional outcome.
Endoscopic valve ablation
e denitive management of posterior urethral
valves consists of surgical resection or ablation of
the obstr uc ting valve membrane. For this purpose,
modern miniaturised endoscopes (Figure 9.7)
Figure 9.7 Cold knife and cutting resectoscope
loop for use with neonatal resectoscope. The
availability of instruments designed for neonatal
use including lasers has simplied management
and greatly reduced the incidence of instrumentation-induced urethral trauma.
Figure 9.8 Position of the cutting loop prior to
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ablation of the valve membrane.
can be used safely even in small premature neonates. e valve leaets are incised from margin to base (rather than fully resected). ese
incisions are conventionally performed in the
5 and 7 o’clock positions (Fig ure 9.8) – with
a further incision at the 12 o’clock position if
required. To minimise the risk of any damage to surrounding tissues we prefer to incise
the valve membrane with a cold knife blade
rather than a cutting diathermy loop. Incision
of the valve membrane at two or three sites is
sucient to relieve the obstruction. It is not
necessary to attempt complete removal of the
valve tissue and, indeed this carries some risk
of damage to adjoining tissues. Practice varies with regard to catheter drainage following
the procedure but this is advisable if signicant
intraoperative bleeding has been encountered.
We favour a follow-up cystoscopy 6–12 weeks
later to ensure completeness of valve ablation.
Some paediatric urologists combine this procedure with a circumcision performed under the
same anaesthetic.
e majority of boys can be eectively and
safely managed by denitive primary surgical treatment of their posterior urethral valves.
Urinary tract diversion is performed less
Posterior urethral valves / Treatment 121
frequently than in the past and there is no convincing evidence that it leads to any improvement
in the prognosis for renal function. Nevertheless,
there are still indications for urinary diversion in
individual cases.
Vesicostomy
Primary cutaneous vesicostomy drainage is
used for the management of boys with markedly
impaired renal function and/or gross vesicoureteric reux. In our centre its use for this purpose
has been largely superseded by reuxing ureterostomy. However, primary cutaneous vesicostomy remains a useful option in situations when
miniaturised instruments are unavailable.
e stoma is created at the apex of the bladder to minimise the risk of prolapse. Closure is
undertaken aer subsequent valve ablation at
around 6–18 months of age depending on the initial indication for selecting vesicostomy and the
child’s level of renal function (Figure 9.9).
Figure 9.9 Cutaneous vesicostomy.
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