Evaluation and management of megaureter

2. Megaureter
Dr. Faheem ul Hassan
Fellow Pediatric Urology
Dr. Gowhar Mufti
Assist. Professor
Pediatric & Neonatal Surgery

3. Megaureter
Megaureter is synonymous with a dilated ureter, or
hydroureter .
By definition, a megaureter is a ureter >8 mm in
diameter.
The megaureter was classified as
primary, referring to a lesion intrinsic to the ureter, and
secondary, denoting a reaction of the ureter to a process
elsewhere.

4. Anatomy
In order to understand pathophysiology, it is important
to have a framework of normal anatomy.
The ureter is divided into three distinct regions
the ureteropelvic junction
the middle spindle
the ureterovesical junction.

5. Anatomy
The ureterovesical junction is
subsequently divided into
the juxtavesical ureter and
terminal ureter.
The terminal ureter then
separates into
intramural and
submucosal segments.
intramural
submucosal

6. Anatomy
The ureter is enclosed in a loose, ill-defined sheath
within the retroperitoneum.
This sheath forms a protective barrier for neoplastic or
inflammatory retroperitoneal processes.

7. Anatomy
Proximally, the ureteral sheath and adventitia become
continuous with the renal pelvis.
Distally, the sheath and adventitia join to form
Waldeyer’s sheath, which extends into the bladder &
trigone

8. Anatomy
The ureter consists of three layers:
adventitia,
muscularis, and
mucosa.

9. Anatomy
The adventitia is composed of collagen loosely
attached to the underlying muscularis, allowing for
free peristaltic activity.

10. Anatomy
The muscularis is arranged in three layers
The inner muscle bundles are arranged longitudinally,
the middle circumferentially, and
the outer longitudinally.
In intramural region all the muscle fibers are placed
longitudinally.

11. Anatomy
The mucosa consists of
multiple layers of
transitional epithelium
lying directly on the
lamina propria

12. Anatomy
The proximal ureter is vascularized predominantly by
an artery originating from the renal artery.
The middle spindle receives a branch from the aorta
and gonadal artery.
The distal ureter is supported by arteries from the
internal iliac, superior and inferior vesical arteries.
A periureteral arterial plexus courses the full extent of
the ureter through the adventitia.

13. Anatomy

14. Classification
The dilated ureter or MGU can be classified into one
of four groups based on the cause of the dilatation:
(1) refluxing
(2) obstructed
(3) nonrefluxing and nonobstructed
(4) both refluxing and obstructed

15. Classification

16. Pathophysiology
The common finding is an abundance of connective tissue in
the abnormal ureter
Lee et al. demonstrated altered collagen to smooth muscle ratio
in megaureters is
Collagen to smooth muscle ratio is
0.52 in normal ureters,
0.78 in obstructed and
1.99 in refluxing megaureters.

17. Pathophysiology
Other studies have demonstrated that smooth muscle
cells in these ureters produce an abnormally elevated
amount of collagen.
The muscles in these ureteral segments have also been
shown to respond abnormally to neurotransmitters,
emphasizing the anomalous behavior of these cells

18. Obstructed megaureter

19. Primary Obstructed megaureter
The primary obstructed megaureter has generated the
greatest interest and investigation.
The primary obstructed megaureter has been reported
in approximately 25% of children with obstructive
uropathy.

20. Primary Obstructed megaureter
It is bilateral in 25%
Four times more often in boys
The left ureter is more frequently affected
Contralateral kidney may be dysplastic or obstructed
in 10–15% of children

21. Primary Obstructed megaureter
Endoscopically, the obstructed ureteral orifice can
have a normal appearance and insert appropriately on
the trigone.
Caulk and Swensen et al proposed that the obstructed
megaureter was similar to the megacolon seen in
Hirschsprung’s disease.
However, this proposition has been refuted based on
histologic evidence showing presence of ganglia

22. Primary Obstructed megaureter
Primary obstructive megaureter is considered a
functional obstruction.
There is thought to be an aperistaltic (adynamic)
segment in the ureter, leading to a lack of propagation
of the ureteral peristalsis
This distal segment has been found to contain
increased levels of collagen type I and III
(predominantly type I).

23. Primary Obstructed megaureter
This increased fibrosis is implicated in the disruption
of intercellular communications which leads to
uretero-arrhythmias and obstruction.
Some scientists have shown evidence of atrophy of
the inner longitudinal muscles in these ureteral
segments (the longitudinal muscles are the ones that transmit peristalsis) and
hypertrophy of outer circular muscle, leading to
obstruction

24. Primary Obstructed megaureter
The fact that many obstructive megaureters resolve with
times has pushed many to define a maturational cause of
obstructive megaureters
The renal urine production begins slightly prematurely,
before the ureter is fully cannulated at its caudal end,
leading to hydroureter.
The full canalization of the mature ureter could then
explain the resolution of the obstructive appearance of the
ureter.

25. Primary Obstructed megaureter
Another maturational theory is that the obstruction
represents a developmental evolution of the distal
ureter from a single, circular muscle layer to the
double layer (circular and longitudinal) of the child.
Other histologic findings include distal ureteral
segments with no muscle tissue present, but simply a
fibrotic, static terminal end.

26. Primary Obstructed megaureter
Yet others have documented distal ureteral segments with
an abnormal muscle that is excessively responsive to non-
adrenergic stimulus, leading to almost tonic contraction.
The proximal, dilated ureteral segment has also been
found to be composed of altered connective tissue, and
this fibrosis and the dilation itself can lead to uretero
arrhythmias and poor peristaltic wave transmission.

27. Primary Obstructed megaureter
The infant collecting system is very pliable and this
dilation allows for the dampening of pressure,
allowing the kidneys to produce urine into a collecting
system at close to physiologic pressures.

28. Primary Obstructed megaureter
other anatomic causes that can lead to a similar
clinical scenario are
congenital distal ureteral strictures and
distal ureteral valves

29. Secondary Obstructive Megaureter
Secondary obstructive megaureter represents an
obstructive process secondary to elevated intravesical
pressure of some other cause. Common causes include
spinal dysraphism and
neurogenic bladder (which may elevate detrusor pressure to over
40 cm H2O, causing a physiologic obstruction and hydronephrosis)
Non-neurogenic voiding dysfunction

30. Secondary Obstructive Megaureter
Other causes of secondary Obstructive megaureter are
Ureterocele
ectopic ureter
bladder diverticula
periureteral fibrosis
infravesical obstruction like Posterior urethral valves
and external compression by retroperitoneal tumor, masses,
or aberrant vessels

31. Refluxing Megaureter

32. Primary & Secondary Refluxing Megaureter
Refluxing megaureters simply represent a refluxing
ureter that is dilated.
The refluxing megaureter is endoscopically
characterized by a gaping lateral ureteral orifice.
Bladder filling and cyclic voiding can transmit
pressure into the ureter, resulting in mechanical
enlargement

33. Primary & Secondary Refluxing Megaureter

34. Primary & Secondary Refluxing Megaureter
The causes may be
short intravesical and submucosal tunnel.
Increased type III collagen
periureteral diverticula
megacystis megaureter syndrome
Prune Belly syndrome

35. Refluxing Megaureter of PBS
Ureters are elongated, tortuous, and dilated
Ureteral orifices are lateral, golf hole in appearance,
and frequently associated with diverticulum.
The distal ureter is characterized by asymmetric
ectasia and is more often involved than the proximal
ureter.

36. Refluxing Megaureter of PBS
Secondary obstruction may occur from kinking and
folding of the redundant ureter.
Primary obstruction has been reported at the
ureterovesical junction in a select group.
Histologically, there is an increase in fibrous tissue at
the expense of normally developed ureteric muscle.

37. Primary & Secondary Refluxing Megaureter

38. Non- obstructing Non-Refluxing Megaureter

39. The non-refluxing non-obstructed megaureter is most
often encountered in the neonate with the antenatal
diagnosis of hydronephrosis.
The fetus makes larger volumes of urine compared to
the infant, and if this diuresis precedes the natural
canalization of the distal ureter, a megaureter may
develop (maturational delay hypothesis).

40. Non- obstructing Non-Refluxing Megaureter
The cases of nonobstructive and nonrefluxing
megaureter due to a cause unrelated to ureteral
anatomy are termed secondary.
It is in this category dilation occurs due to
high fetal urine output (diabetes insipidus or mellitus, sickle
cell nephropathy).
increased compliance of fetal ureter due to elevated
collagen type II,

41. Non- obstructing Non-Refluxing Megaureter
partial or transient obstruction during development due to
ureteral folds or delay in normal peristalsis
urinary tract infections can lead to temporary ureteral
dilation due to the presence of bacterial endotoxins that can
inhibit peristalsis

42. Non- obstructing Non-Refluxing Megaureter
McLellan et al reported resolution of the non-refluxing
megaureter in the majority of children, with the time to
resolution based on the initial grade of hydronephrosis.
Children with grades 1–3 hydronephrosis resolved at a
median age of 13-35 months and children with grade 4 and
5 hydronephrosis resolved at a median age of 48 months.

43. Obstructed Refluxing Megaureter

44. Obstructed Refluxing Megaureter
The refluxing obstructed megaureter
results from ectopic insertion of the
ureteral orifice in the region of the
bladder neck.
During bladder filling, the bladder neck
is closed, acting as a distal obstruction.
With voiding, the bladder neck opens and
allows for reflux.
A cyclic voiding cystourethrogram may
be required for diagnosis in suspected
cases.

45. Diagnosis
The routine use of fetal sonography has dramatically
increased the diagnosis of the megaureter.
Cases detected later in life often present with urinary tract
infection, hematuria, and/or pain

46. Diagnosis
With routine fetal sonography the megaureter is noted to
occur in 23% of asymptomatic neonates, surpassed only by
hydronephrosis, which is seen in 41%.
The increased incidence of the megaureter can be explained
by a more liberal use of fetal sonography and improved
technology.

47. Diagnosis
An unknown percentage of infants with
asymptomatic megaureter will subsequently
develop symptoms.
This places a greater burden on imaging technology
and our clinical ability

48. Ultrasonography
Ultrasonography is the primary & initial imaging modality
in the assessment of megaureter.
Evaluating the size, shape, tortuosity, and bulbar appearance
of the ureter & pelvis can often give the impression of an
obstructive process.

49. Ultrasonography
Ultrasonography is a simple & safe study that can provide
important information on
Renal size
Parenchymal thickness
Echogenicity , and architecture
Renal pelvis and ureteral dilation and
Bladder wall thickness

50. Ultrasonography
The course of the ureter may be traced from the
renal pelvis to its distal insertion
The ureter may enter an obstructed ureterocele or
and in an ectopic location within the bladder neck
or posterior urethra

51. Ultrasonography
An obstructed distal segment may be recognized when a
peristaltic wave of urine abruptly stops and rebounds into the
dilated proximal ureter
The echogenicity of the kidney is a helpful parameter used to
distinguish between and obstructive and a non-obstructive
process, with increased echogenicity supporting obstruction

52. Ultrasonography
A renal resistance index (RI) >0.70 has been suggested to
correlate with obstruction.
It is important to remember that grey-scale ultrasonography
is only descriptive and provides no details on renal function
or drainage

53. Ultrasonography

54. Voiding cystourethrography
If renal pelvis or ureteral dilation is observed on
ultrasonography, a voiding cystourethrogram is needed to rule
out reflux
This also allows for the complete anatomic evaluation of the
bladder and urethra

55. Voiding cystourethrography

56. Voiding cystourethrography
The cyclic voiding cystourethrogram is beneficial
when an ectopic, sphincteric ureter is suspected.
In this scenario, the ureter can be obstructed when the
bladder is at rest and refluxes only during the voiding
phase.

57. IVU
Excretory urography is waning as a diagnostic
modality in the evaluation of pediatric uropathy
because only limited information is gained.
Stool, bowel gas, and immaturity of the neonatal
kidney limit its utility.
On a rare occasion, excretory urography may play a
role when anatomic definition is required.

58. Renography
Presently the most commonly used tool for the
evaluation of obstructive nephropathy is the diuretic
renogram
Two most commonly used radiotracers for
renography are
Technetium Tc99 DTPA (diethylene triaminepenta-
acetic acid) and
Tc99 MAG3 (mercaptoacetyltriglycine)

59. Renography
DTPA is a glomerular agent and provides limited information
during the first month of life because of a low neonatal GFR
MAG3 is extracted by the kidney and dependent on effective
renal plasma flow not GFR.
It is important to have a separate activity curve generated for
the kidney and the ureter when assessing for an obstructive
pattern.

60. Renography
Obtaining activity curves over the ureter will help confirm
distal ureteral obstruction.
Variables involved in diuretic renography that can influence
study findings are
Tracer dosing
Timing of diuretic administration
Patient hydration and
Determination of the study areas of interest

61. Renography
The well-tempered renogram has three important
components:
1; 10–15 ml/kg crystalloid hydration prior to the study,
2: 1 mg/kg of Lasix administered at the peak of tracer
accumulation in the kidneys (plateau), and
3; a catheter in place during the entire study

62. Renography
Range of t½ values associated with obstructed or
unobstructed collecting systems
<10 min unobstructed
10–20 min equivocal
>20 min obstructed
However, in cases of megaureter, the dilated collecting
system can have such a large capacity that the drainage of the
radiotracer is delayed despite the absence of true obstruction

63. Renography
Attempts to improve renography include the F-15
method, in which Lasix is given 15 min before
tracer dosing
This method is thought to decrease false-positive
studies in children with dilated or poorly functioning
systems,

64. Renography
Historically, a Whitaker’s test was used in cases of
hydronephrosis to rule out obstruction using
pressure/flow measurement; however, it is rarely
used now due to the invasive nature.

65. Magnetic resonance urography (MRU)
Magnetic resonance urography (MRU) may play a
future role in the evaluation of the megaureter
This imaging modality may become the anatomic
study of choice, particularly when renal compromise
is present.

66. Cystoscopy
Obstructing—normal orifice
Refluxing –wide ureteric orifice

67. Management
Therapeutic intervention of the megaureter is dependent on
accurate classification.
Secondary causes of a megaureter justify treatment of the
primary problem, whether it is due to a neurogenic bladder,
posterior urethral membrane, ureterocele, diabetes insipidus,
or a retroperitoneal process.

68. Refluxing megaureter
There is growing evidence that operative intervention is not
required in all neonates with refluxing megaureters,
especially when identified during the work-up of
asymptomatic antenatal hydronephrosis.

69. Refluxing megaureter
High-grade VUR in neonates occurs more often in males than
females, and improvement can occur during the first year of
life.
There is little reason to proceed with early intervention,
particularly when an infant has remained symptom-free on
prophylactic medical management.

70. Refluxing megaureter
Surgery is only considered for persistent high-grade reflux in
older children (especially with recurrent pyelonephritis) and
in infants that have failed medical management.
As the complication rate for ureteroneocystostomy is high
when performed in children under the age of 1 year,
cutaneous ureterostomy or vesicostomy may be used as a
temporizing measure in infants requiring surgical
intervention

71. Refluxing megaureter
Megacystis–megaureter occurs in approximately 80% of
boys diagnosed antenatally with bilateral reflux and found to
have renal impairment
It is a large-capacity, thin-walled bladder with massive
primary vesicoureteral reflux.
megacystis–megaureter does not appear to be due to bladder
outlet obstruction.

72. Refluxing megaureter
There is progressive upper tract HUN and bladder
enlargement as a result of recurrent cycling of urine
into the upper tract
Double voiding can temporize this process in
children who are toilet trained

73. Refluxing megaureter
Intermittent bladder catheterization can be an effective
technique of eliminating residual urine in neonates who are
not toilet trained
Ultimately, children with a megacystis–megaureter are best
served by operative correction of the reflux.

74. Obstructed megaureter
Fetal sonography has identified a substantial number of
neonates with an obstructed megaureter, many of whom will
not have clinical symptoms
Medical management, based on prophylactic antibiotics and
watchful waiting, allows for potential spontaneous regression
of the obstructed megaureter.

75. Obstructed megaureter
Renal parenchymal thickness and function must be
objectively followed with sonography and
renography in order to identify renal compromise.
Repair of the infant megaureter is technically
feasible but remains a challenge even in experienced
hands.

76. Obstructed megaureter
Secondary operative procedures have been reported
as high as 10% when correcting an obstructed
megaureter in an infant <8 months of age.
It is best to delay the repair until the child is older
than 12 months of age

77. Obstructed megaureter
Occasionally, a neonate with an obstructed
megaureter will present with severe renal
compromise.
In this situation, a distal cutaneous ureterostomy can
provide temporary relief, adequately draining the
upper urinary tract and decreasing the risk of
infection.

78. Non-refluxing, non-obstructed megaureter
Approximately 6–10% of neonates diagnosed with
fetal sonography will have a non-refluxing non-
obstructed megaureter.
A functional study is required to confirm adequate
ureteral drainage.

79. Non-refluxing, non-obstructed megaureter
The initial medical management will be prophylactic
antibiotics.
Children with a non-refluxing non-obstructed
megaureter maintain normal renal function and the
megaureter often reverts to normal

80. Obstructed refluxing megaureter
The obstructed refluxing megaureter occurs as a
result of either a laterally positioned aperistaltic
distal segment or ectopic insertion of the ureter into
the bladder neck.
Although the condition is not an emergency,
operative correction is required in order to diminish
the risk of upper urinary tract deterioration

81. Secondary Refluxing
Secondary reflux must be treated by addressing the
cause of elevated intravesical pressure
Reflux in children with posterior urethral valves is
treated by
valve ablation and proper bladder management

82. Secondary Refluxing
Neurogenic bladders with elevated DLPP (>40 cm H2O)
must be treated with a combination of
Medical therapy (i.e., anticholinergic
medication)
Clean intermittent catheterization and
Surgery , if necessary

83. Secondary Refluxing or Obstructive Megaureter
Prune Belly and diabetes insipidus can be managed
with observation, presuming the appropriate medical
therapy

84. General principles of treatment
No surgery should be performed as long as
renal function is not significantly affected and
Urinary tract infections are not a major issue
Instead, antibiotic suppression with close observation is all
that is required.
surgical repair is warranted between 1 and 2 years of age if
the condition is worsening

85. General principles of treatment
In certain rare cases, early intervention in the form
of ureterostomy and vesicostomy becomes necessary
In terms of forming algorithms of treatment, no
good parameters dictate the children that will
resolve and those that will worsen.
In general, over 70% of cases resolve over 2 years of
follow-up.

86. Indications of surgical treatment
Primary obstructive megaureter
Poor function (<35-40%)
A severely scarred kidney
Recurrent Febrile UTI
Decreasing function on serial studies
Failure to improve after a reasonable period of observation
Solitary kidney---treat aggressively

87. Operative approach
Temporary diversion
A percutaneous nephrostomy is helpful when rapid drainage is
required.
small nephrostomy tubes are difficult to maintain longer than a few
weeks.
When prolonged drainage is required, a distal ureterostomy is
appropriate.
A pyelostomy results in unnecessary proximal diversion when the
pathology exists at the bladder level.

88. Temporary diversion
A cutaneous ureterostomy carries minimal
morbidity, allows for rapid continuous
decompression, and can often be performed in the
outpatient setting
It may be used for the severely obstructed neonatal
megaureter.

89. Definitive reconstruction
Definitive urinary reconstruction can be either
intravesical, extravesical, or combined.
Straightening and tapering the ureter without
devascularization is required.
The functional ability of the ureter to transmit urine
is inversely related to the size of the megaureter.

90. Definitive reconstruction
The ureter is tapered to achieve a 4–5:1 ratio of
tunnel length to ureteral diameter necessary for an
antirefluxing repair.
Tapering should be gradual to prevent a sharp
gradient, which can act as a pseudo-obstruction.
Commonly used Tailoring techniques include
ureteral imbrication and formal ureteral excision

91. Imbrication
Ureteral imbrication is appropriate for marginally
dilated ureters.
Two common imbricating techniques are the
Starr and Kalicinski plications.

92. Imbrication

93. Imbrication

94. Imbrication
Advantages of Imbrication
Preservation of the blood supply,
Minimal risk of urinary leak, and
Infrequent obstruction
Disadvantage
Adds unwanted bulk, making the ureter difficult
to reimplant

95. Excisional tapering
Formal excisional tapering of the ureter is required
for extremely bulky ureters or a bilateral process
A ureteral stent can be placed:
To decrease urinary extravasation
To provide a scaffold for the ureter to conform to
To prevent kinking
To bypass the tapered region, which initially may act as
an obstruction due to edema

96. Excisional tapering

97. Excisional tapering
In most situations, only the portion of the ureter
which is going to be placed within the bladder and 1
or 2 cm beyond needs to be tapered.
There should be a gentle transition from the ureteral
hiatus at the bladder to the non-tapered ureter

98. Postoperative management
The stent can be removed 3–7 days after
imbrication, and 7–14 days following an excisional
repair
Ureterograms at the time of stent removal are not
necessary
Administration of a broadspectrum antibiotic prior
to removing a stent decreases the possibility of
urosepsis

99. Postoperative management
Postoperative ureteral edema can persist for 6
weeks.
Imaging studies, either sonography or renal
scintigraphy, should be avoided during that time.

100. Postoperative management
initial images on sonography may show increased
hydronephrosis and hydroureter when compared
with preoperative sonographic imaging, due to;
Compliant proximal ureter and
Relative resistance to flow through the tapered segment.

101. Postoperative management
A 6-week postoperative ultrasound, showing hydronephrosis (left) and a
hydroureter (right). The preoperative ultrasound was normal.

102. Postoperative management
A 3-month postoperative ultrasound. The hydronephrosis (left) and
hydroureter (right) has resolved.

103. Postoperative management
A postoperative voiding cystourethrogram at 6 months is
performed to confirm the absence of vesicoureteral reflux.
Prophylactic antibiotics can be discontinued with resolution
of the reflux.

104. Outcome
Procedure Successful outcome
Imbrication 93-95%
Excisional tapering 74-90%
Non-tapered uretero-
neocystostomy
Less success more
complications and morbidity

105. Complications
The two most common complications are obstruction and
persisting reflux.
inherent ureteral characteristics and bladder dysfunction
affect a successful outcome
Increased collagen deposition and altered smooth muscle
may be the etiology for a higher rate of persisting
vesicoureteral reflux following repair

106. Complications
Postoperative edema can lead to obstruction which might
take 2–3 weeks. it may require temporary percutaneous
nephrostomy
Transient mild reflux noted at 6 months can resolve with
further time.
Reflux persisting greater than 3 years is unlikely to improve

107. I have a perfect cure of sore throat;
cut it
Thank You

108. Index case
12 years male child
Operated case of
1; Meatotomy 5 Aug 2005
2; Chordee correction 28 jan 2008
3; Residual Chordee correction 30 Jan 2008
Urethroplasty by modified Bracka 18 Aug 2009

109. Index case
On 5 Jan 2015 patient presented with pain left flank with
poor urinary stream
USG : B/L HUN with significant PVRU (160ml) and
thickened and trabeculatd bladder.
DTPA
LEFT RIGHT
SPLIT FUNCTION 27.9 72.1
GFR 49.2 72.8

110. Index case
MCU was normal

111. Index case
IVP B/L HDN
Rt. Ureter visualised
Lt ureter not visualised
(secondary PUJO)
B/L ureters grossly dilated

112. Index case
Cystoscopy Jan 2015
Normal caliber anterior and posterior urethra, no evidence of PUV,
small mucosal fold in anterior urethra non-obstructing
AH pyeloplasty Jan 2015
Kidney hydronephrotic with intrarenal pelvis
Dilated ureter

113. Index case
Uroflometry : normal study
USG 9 Dec 2015
Rt. Kidney GII-III HDN
Lt. Kidney GIII-IV HDN
B/L ureters grossly dilated
PVRU 22 ml

114. Index case
IVU in Aug 2015 showing b/l GR III_IV HDN with hydroureter

115. Index case
DMSA; Normal tracer uptake in both kidneys. A wedge
shaped cortical defect is seen in Lt. Kidney
EBC- 360 ml
PVRU- 22 ml
Calculated GFR- 132

116. Index case
Presently patient is assymptomatic
No history of
Thin stream
Dysurea
Incontinence
Urgency
Constipation
Fever & pain

117. Index case
Abdomen is soft
Coronal hypospadias
Anal tone is normal

118. Index case
Abdomen is soft
Coronal hypospadias
Anal tone is normal