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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_32_библиотеки_им_акад_М_И_Перельмана
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8
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Duplication Anomalies, Ureteroceles
and Ectopic Ureters
PARVIZ HAJIYEV and BERK BURGU
Topics covered
Classication
Embryology
Pathology and denitions
INTRODUCTION
Complete or partial duplication of the upper
urinary tract is a relatively common congenital
anomaly with autopsy and radiological data indicating an overall incidence of the order of 1–3%.
e most common form is partial (incomplete)
duplication, in which two ureters emerge separately from the kidney but then converge to form
a single ureter draining via a single ureteric orice. Partial forms of duplication rarely give rise
to clinical problems and may be picked up as an
incidental nding during urological investigation
for unrelated symptoms.
Complete forms of duplication are characterized by two separate collecting systems in the
duplex kidney with ureters which remain separate throughout their length, entering the lower
urinary tract via two separate ureteric openings.
Investigations
Management
Complete duplication is much rarer, occurring
in less than 1% of individuals, mainly females.
Unlike partial duplication, complete duplication
anomalies are oen of clinical signicance. ey
may be associated with a range of symptoms and
complications including urinary tract infection,
urinary incontinence, bladder outow obstruction and functional renal damage. Duplication
occurs bilaterally in 40% of cases but the anatomical pattern is oen dierent between the two
upper tracts.
Complete duplication is frequently detected on
routine prenatal ultrasound screening but further
evaluation with diagnostic imaging is required
postnatally. Clinical presentations include urinary
tract infection, urinary incontinence, obstructed
voiding, pain and urolithiasis.
Upper tract duplication has a familial tendency and there is an incidence of 8% in close
relatives.
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EMBRYOLOGY
is is considered in Chapter 1 but can be briey
summarized as follows:
During the fourth week of gestation the ureteral bud branches o from the mesonephric
duct and advances toward the metanephric blastema to initiate development of the embryonic
kidney from around 32 days. A single ureteral
bud will usually induce normal nephrogenesis
and give rise to a single renal pelvis and normal
calyces. Division (bifurcation) of the ureteral
bud before it enters the metanephros results in
partial duplication – with the ureteral anatomy
being determined by the level of bifurcation.
Complete duplication occurs when the mesonephric duct gives rise to two separate ureteral
buds which each make contact with the metanephric blastema (Figure 8.1). A ureteral bud
derived from an aberrant (ectopic) position on
the mesonephric duct is more likely to penetrate and abnormal part of the metanephric
blastema – resulting in defective nephrogenesis
and renal dysplasia.
In complete forms of duplication the more
caudal of the two ureteral buds (draining the
lower pole of the kidney) has a tendency to open
in a superior and lateral position in relation to the
trigone. is may result in a shorter intramural
course of the distal ureter in the bladder predisposing to reux into the lower pole moiety of the
duplex kidney.
Paradoxically, the ureter draining the upper
pole moiety invariably drains in a more distal
(caudal) position in the urinary tract than the
lower pole ureter. is characteristic feature of
the ureteral anatomy in upper tract duplication is
described a s the Meyer-Weigart law. In females, an
ectopic upper pole ureter may enter the lower urinary tract at the bladder neck or more distally at a
level below the bladder neck and striated sphincter muscles. In the most severe forms of ectopia,
the ureter opens at the introitus or drains into the
vagina. In males, however, an ectopic upper pole
ureter always drains at a supra sphincteric level,
typically connecting with the vas, seminal vesicle
or ejaculatory duct. e embryological origin of
ureteroceles remains poorly understood.
Figure 8.1 Embryological origins of complete
duplication. (a) Accessory ureteral bud (blue)
arising in an abnormally cephalad position on
the mesonephric duct (green). (b) By 12 weeks
the upper pole ureter has been carried with the
mesonephric duct to an abnormally distal ectopic location. The more caudal ureteral bud (red)
may become incorporated into a superolateral
position on the trigone, with a short submucosal tunnel predisposing to reux. The relative
positions of the ureteral orices on the trigone
are also illustrated. The characteristic anatomical
patter of duplex ureters is dened by the MeyerWeigart law.
CLASSIFICATION
Upper tract duplication is subdivided into
●
Complete duplication
●
Partial duplication
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e anomalies associated with complete duplication include
●
Upper pole: ureterocele, ectopic ureter, upper
pole renal dysplasia
●
Lower pole: vesicoureteral reux
e anomalies associated with partial duplication
include
●
Pelvi ureteric junction obstruction (lower pole)
●
“Yo yo” reux between the two ureters above
their point of convergence. However, this
is a doubtful clinical entity in children of
unknown clinical signicance
Ureteroceles (Figure 8.2)
ese are classied as
●
Intravesical (entirely within the bladder)
●
Extravesical or ectopic (ie, a portion extends
beyond and below the bladder neck into the
urethra)
A ureterocele is dened as a cystic dilation of
the intravesical segment of the distal ureter. e
overall incidence of duplex system ureteroceles
is 0.02% – with the majority (80%) occurring
in females. e renal cortex drained by a ureter
Figure 8.2 Ureteroceles. (a) Cystic dilatation of upper ureteral bud with aberrant interaction with the
metanephric blastema leading to (b) duplex ureterocele and dysplastic upper pole moiety. (c) Single
system orthotopic ureterocele. (d) Duplex ectopic ureterocele. (e) Large prolapsing caecouretrocele
extending down between the decient trigone and urethra anteriorly and vagina posteriorly.
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terminating in a ureterocele is oen dysplastic
and the ureter and upper pole collecting system
are dilated (hydronephrotic). A ureterocele may
lie entirely within the bladder, in which case it
is unlikely to interfere with voiding and urinary
continence. However, up to 50% of duplex ureteroceles are termed “ectopic” because they extend
extravesically and encroach upon the bladder outlet and proximal urethra. e largest variety is the
caeco ureterocele, which extends further down
into the urethra and may appear as a cystic mass
in perineum by the external urethral meatus.
Ectopic ureteroceles can cause bladder outow
obstruction giving rise to voiding dysfunction
and elevated intravesical pressure – which may
have the potential to cause obstructive damage
to the contralateral kidney. Elevated intravesical
pressure caused by a prolapsed ectopic ureterocele
may also exacerbate any existing vesicoureteral
reux (VUR) into the ipsilateral lower pole.
e majority of infants with duplex system
ureteroceles are now identied by prenatal ultrasonography. In infants in whom the abnormality
has not been identied prenatally, the most common clinical presentation is with urinary tract
infection in the early months of life.
Less frequently, the condition presents with
symptoms of voiding dysfunction and outow
obstruction. Although rare, prolapsed ectopic ureterocele is nevertheless the most frequent cause of
urethral obstruction in girls and may occasionally
be accompanied a visible cystic swelling.
In addition to symptoms caused by outow
obstruction, other symptomatic presentations in
older infants and children include febrile or nonfebrile urinary infections, failure to thrive and
recurrent abdominal/pelvic pain. Duplication
may rarely present with urolithiasis secondary to
infection and obstruction.
Whereas the majority of ureteroceles occur in
duplex systems, approximately 10% of ureteroceles are associated with a single (non-duplex)
upper urinary tract. ese ureteroceles (termed
“orthotopic” or “single system”) are almost always
intravesical and do not interfere with voiding.
Dilatation of the ipsilateral ureter and upper tract
is only of mild or moderate severity and function
in the ipsilateral kidney is usually either normal
or only mildly impaired.
ECTOPIC URETER
is is dened as ureter which enters the urinary
tract in a more caudal position than the normal
point of entry on the trigone. e estimated incidence is 0.01% and it occurs mostly in females – in
whom the ectopic ureter may open into the urethra, vagina or, very rarely, the cervix or uterus.
In males, an ectopic duplex ureter may drain into
the proximal urethra, ejaculatory duct or seminal
vesicles.
Depending on the level at which the ectopic
enters the lower urinary (or genital) tract in relation to the sphincter complex it is dened as being
either supra sphincteric or infra sphincteric.
Supra Sphincteric Ectopic Ureter
Because aected children are continent the
diagnosis is usually made following the nding of dilatation of the upper pole ureter and/
or collecting system on routine prenatal screening or during the investigation of urinary tract
infection.
Infra Sphincteric Ectopic Ureter
(Figure 8.3)
As with supra sphincteric forms of ectopic ureter, this anomaly may be identied following the
discovery of dilatation on prenatal ultrasound
screening. Alternatively, it may come to light
during investigation of urinary tract infection
or symptoms. e classic symptomatic presentation is with constant dribbling of urine which is
superimposed upon an otherwise normal pattern
of voiding and urinary continence. In theory,
this characteristic pattern should serve to distinguish ectopic ureter from other causes of urinary
incontinence but in practice the clinical picture
may be less diagnostic. For example, some girls
remain dry overnight when lying horizontally
and others may experience pooling of urine in
the vagina which may enable them to remain
relatively dry for variable periods during the daytime. e picture may also be complicated if the
girl also suers from wetting due to dysfunctional
voiding – as well as experiencing urinary leakage
Ultrasonography 107
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during postnatal evaluation of prenatally detected
cases or during the investigation of urinary tract
infection.
COMPLICATIONS OF PARTIAL
DUPLICATION
e term “Yo Yo” reux is applied to the possible
crossow of urine between the two ureters of a
partial duplication (limbs of a Y) above their convergence to form a single ureter. Although, postulated as a possible cause of loin pain in adults
there is no evidence that it causes any symptoms
in children. Pelvi ureteric junction obstruction in
duplex systems almost invariably occurs in the
lower pole of a partial duplex kidney (bid pelvis).
INVESTIGATION
Figure 8.3 Diagrammatic representation of infra
sphincteric ectopic ureter.
from the ectopic ureter. Finally, small volumes
of urine collecting in the vagina may become
infected and present as a vaginal discharge – a
relatively common symptom in girls which does
not usually merit imaging of the urinary tract.
Physical examination is rarely conrmatory
and the diagnosis is based on the characteristic
pattern of the incontinence and the ndings of
imaging studies. Because duplication is commonly bilateral the presence of a complete or partial duplex system on one side should always raise
suspicion of a contralateral duplex system with an
occult upper pole and ectopic ureter.
VESICOURETERAL REFLUX
Complete duplication is accompanied by VUR
into the ipsilateral lower pole ureter in approximately 50% of cases. is is usually identied
During the physical examination the external
genitalia and urethral orice should be inspected,
looking for dampness in the region of the introitus. Very occasionally a bulging ureterocele can
be observed (Figure 8.4).
ULTRASONOGRAPHY
Using ultrasound, it is possible to assess the distribution and severity of dilatation (hydro ureter
Figure 8.4 Prolapsed ureterocele emerging at
the introitus of a neonate.
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Figure 8.5 Bladder ultrasonography demon-
strating large ureterocele and dilated upper
pole ureter behind the bladder.
and hydronephrosis) and the appearances of the
renal parenchyma in the upper and lower poles
of both kidneys. A ureterocele can almost always
be visualized on ultrasound, providing the bladder is full (Figure 8.5). Likewise, an ectopic ureter
which is dilated can be visualized lying behind
the bladder. However, cases of “cryptic duplication” may be missed on ultrasound because the
upper pole is small and dysplastic and the ectopic
ureter is not dilated and not readily detectable on
ultrasound.
RADIONUCLIDE SCAN
Functional imaging with
cinic acid (DMSA) scintigraphy is performed to
assess the distribution of function between the
two kidneys and between the upper and lower
pole moieties of a duplex kidney (Figure 8.6).
99m
Tc DMSA can also help to identify an occult
duplex system by demonstrating poorly functioning dysplastic upper pole parenchyma
associated with an infra sphincteric ectopic
ureter. Dynamic renography with
has the advantage of providing information on
drainage as well as dierential function but is
less accurate than
dierential function in the two moieties of a
duplex kidney.
99m
Tc dimercaptosuc-
99m
Tc MAG3
99m
Tc DMSA for quantifying
Figure 8.6 DMSA scintigraphy in a child with
bilateral duplex system ureteroceles. Left upper
moiety non-functioning, minimal function in thin
rim of renal parenchyma in hydronephrotic right
upper moiety. Normal function in both lower
moieties.
VOIDING
CYSTOURETHROGRAPHY
(VCUG)
e VCUG plays an important role when planning management of duplication anomalies. It
is an essential investigation if there is any suggestion of lower pole VUR (which is present in
approximately 50% of cases) and also provides
dynamic anatomical information on the ureters,
bladder and urethra. is may be particularly
helpful in demonstrating partial obstruction of
the bladder neck and proximal urethra by a prolapsing ureterocele.
Reux into the lower pole of a complete duplex
kidney has a characteristic appearance which
is likened to a “drooping ower” (Figure 8.7).
Reux into the upper pole of a complete duplex
system is rare. When a VCUG demonstrates
reux into both poles this is usually indicative of
a partial duplication. e nding of contralateral
VUR may be an important factor when devising
an overall plan of management.
Figure 8.7 VCUG demonstrating bilateral lower
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pole VUR with characteristic “drooping ower”
appearances. Displacement of left lower pole
ureter by grossly dilated upper pole ureter.
Management 109
MAGNETIC RESONANCE
UROGRAPHY
Magnetic resonance (MR) urography has been
used on a selective basis for investigating complex
patterns of duplication and detecting a poorly
functioning dysplastic upper pole associated
with infra sphincteric ectopic ureter. However,
it is rapidly becoming the rst line investigation
of choice in girls whose urinary incontinence is
suspected to be related to a possible ectopic ureter
(Figure 8.8). MR urography can yield information on function as well as providing an accurate
delineation of anatomy and vasculature. It does
not entail any exposure to radiation but is relatively costly and requires the use of sedation or
general anesthesia to ensure the child remains
still for the duration of the scan.
CYSTOSCOPY
Although not routinely indicated, cystoscopy can
nevertheless make an important contribution to
Figure 8.8 MR Urogram demonstrating
an “occult” duplex ectopic ureter which
could not be visualized by other imaging
techniques.
diagnosis and management in selected cases. For
example, visual assessment by cystoscopy (and
vaginoscopy) may provide valuable additional
information on ureteroceles which was not
forthcoming from diagnostic imaging and it may
also occasionally identify an occult ectopic ureteral orice. Endoscopic techniques are widely
used for the surgical management of ureteroceles
and may also be used for endoscopic correction
of VUR.
MANAGEMENT
Upper tract duplication is characterized by
considerable diversity of anatomy and function. In addition, it may either be detected
prenatally or present clinically with diering
symptoms, notably urinary tract infection or
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urinary incontinence. Accordingly, there is no
single approach to management – which must be
adapted to account of the anatomy, function and
presenting features of each individual case.
Prenatally Detected Duplication
e majority of infants with prenatally detected
upper tract duplication are asymptomatic at the
time of birth and have no abnormal clinical ndings on examination.
e aims of management of infants with prenatally detected duplex kidneys can be summarized as:
●
Prevention of febrile urinary tract infections
which might pose threat of new pyelone-
phritic scarring or progression of existing
renal damage.
●
Relief of obstruction.
●
Correction of anatomical abnormalities
which would otherwise be destined to cause
symptoms, notably urinary incontinence, in
later childhood.
upper pole system. In infants with prenatally
detected ureteroceles, it is performed with the
intention of reducing the risk of infection in the
obstructed system and protecting the upper pole
parenchyma from infective and/or obstructive
damage. It can also be used as temporizing measure in children who present with severe infection in the upper pole system.
Endoscopic puncture of a small or medium
sized ureterocele can be performed with a 3 Fr
Bugbee electrode or with holmium laser inserted
via the working channel of a 7.5–10 Fr pediatric
cystoscope (Figure 8.9). Alternatively, the ureterocele can be incised with an electrical hook
However, the long-term natural history of asymptomatic infants who have been born with less
severe forms of duplication is not well documented. For this reason, it is important to avoid
submitting healthy infants to surgical intervention which is not justied or which is needlessly
invasive.
A number of studies have reported the successful conservative management of some forms of
prenatally detected duplication such as intravesical ureteroceles associated with non-functioning/
cystic dysplastic upper pole tissue or upper
pole moieties which appear non-obstructed on
dynamic renography. However, the duration of
follow up in such studies has been relatively short
(<10 years) and the longer term outcomes of conservative management are not yet known.
Endoscopic Incision
is is the least invasive form of intervention and
is used mainly to decompress an intravesical ureterocele and facilitate drainage in an obstructed
Figure 8.9 Diagrammatic representation of
simplest intervention-endoscopic puncture. The
ureterocele can also be incised more extensively by cold knife or laser.
Management / Ectopic Ureter 111
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or cold knife. e horizontal incision should be
sited close to the junction between the ureterocele and bladder wall to prevent the creation of a
potentially obstructive ap and to reduce the risk
of inducing reux.
e main drawback of endoscopic incision is
that it can cause the onset of reux in a previously
non-reuxing system. is occurs in approximately 50% of cases and is associated with a signicant incidence of urinary infection. For this
reason, endoscopic incision results in a requirement for subsequent secondary surgical intervention in at least 20% of cases.
Endoscopic incision can also be applied to
the management of extravesical ureteroceles.
However, an additional incision distal to the
bladder neck at the lowest part of the ureterocele is advisable to prevent the decompressed
ureterocele from lling with urine and causing
bladder neck obstruction at the time of voiding.
Although, endoscopic incision of an extravesical ureterocele may be a worthwhile short-term
measure is rarely curative and additional surgical intervention is required in the majority of
cases.
Depending on its size and degree of dilatation of the upper tract dilatation, a single system,
orthotopic ureterocele can also be managed by
endoscopic incision. However, because this carries a signicant risk of inducing reux some
pediatric urologists favor surgical excision of the
ureterocele combined with ureteral reimplantation. is is a relatively straightforward procedure with a high success rate.
of ureter. A suprapubic incision and transvesical approach are required to provide adequate
access to the region of the bladder neck for
excision of a prolapsing ectopic ureterocele
(caecoureterocele). is is a technically challenging operation because the bladder neck is oen
decient in the vicinity of the ureterocele and
bladder neck reconstruction may be required.
e parents should be advised of the possible risk
of sphincter weakness incontinence. In this context, however, there is good published evidence
that bladder neck/sphincter weakness in such
cases is more likely to be related to a preexisting
congenital anatomical deciency than a complication of the surgery.
Intravesical ureteroceles and some extravesical ureteroceles can be managed by upper pole
heminephrectomy and excision of an accessible
length of ureter performed through a single
loin incision. Once the ureter has been transected, urine is aspirated from the ureterocele
and residual length of distal ureter – leaving the
decompressed ureterocele and “ureteral stump”
in situ. When used selectively this “simplied
approach” constitutes denitive treatment in the
majority of patients, with only 10–20% requiring subsequent excision of the ureteral stump
and ureterocele and reimplantation of the lower
pole ureter.
e various procedures described above are
being increasingly performed by a minimally
invasive (laparoscopic or robotic assisted) rather
than open surgery.
Upper Pole Heminephrectomy
or Heminephroureterectomy
(Figure 8.10)
Although now being performed less frequently,
this procedure retains a valuable role when the
upper moiety is non-functioning or poorly functioning and the collecting system and ureter are
grossly dilated. e denitive surgical management of a large and/or ectopic ureterocele consists of removing the upper pole moiety and as
much of the ureter as can be accessed through a
ank incision. A second (groin) incision is then
used to remove the remaining (distal) section
Ectopic Ureter
Supra-sphincteric
In most cases, the ipsilateral upper pole is nonfunctioning and heminephrectomy (open or
laparoscopic) is sucient. However, this type
of ectopic ureter is occasionally associated with
reux into the upper pole moiety – for which
it is also necessary to remove the ureter. In the
rare cases in which there is a worthwhile degree
of function in the upper pole the ectopic upper
pole ureter and the lower pole ureter can be reimplanted together “en-bloc” into the bladder.
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