• A ureteropelvic junction (UPJ) obstruction can be thought of as a
restriction to flow of urine, from the renal pelvis to the ureter, which,
if left uncorrected, leads to progressive renal deterioration.
• The response to obstruction is the development of renal pelvic
hypertrophy, in which the kidney compensates to maintain adequate
• Prevalence of antenatally detected hydronephrosis (ANH) ranges from 0.6-5.4%
• Bilateral in 17-54%
• ANH resolves by birth or during infancy in 41-88% patients
• Urological abnormalities requiring intervention are identified in 4.1- 15.4%
• USG - mainstay of fetal imaging
• Found in 50% of patients diagnosed with antenatal hydronephrosis.
• 5% - within the first year of life , 50% - before the age of 5 years
• Recognized in nearly 1 in 500 live births
• Boys: Girls = >2:1 Left : Right = 2:1
• Bilateral in 10-40%
PATHOLOGIC CHANGES OF OBSTRUCTION
• kidneys - enlarged, cystic
• Dilation of the pelvis and ureter
and blunting of the papillary tips
• Cortex edematous & slightly
• diffuse thinning of cortex and
• Widespread glomerular collapse
and tubular atrophy, interstitial
fibrosis, and proliferation of
connective tissue in the
collecting system --- 5 to 6
weeks after obstruction
Differentiation is the process of cells attaining specific functional traits to
permit specialized functions and organization into tissues.
It is the basis for renal function,
Obstruction affects these finely tuned patterns, as can be seen histologically
in a severely obstructed kidney with dysplasia.
A universal characteristic of obstructive nephropathy
appears to be renal fibrosis
It is seen as infiltration of the interstitium with abnormal amounts of ECM,
including collagen, fibronectin, and other connective tissue proteins.
Their presence disrupts the normal interconnections between cells that
permit functional integration of the renal tissues.
• Modulation of renal fibrosis may be a significant potential target for managing
obstructive nephropathy,but the delicate balance of these factors needs to be understood
to a greater degree.
• Nitric oxide has also been shown to regulate the development of obstructive fibrosis
postnatally and may play a similar role prenatally
• Increased nitric oxide generation reduces the degree of interstitial fibrosis
Renal function is regulated at numerous levels, including vascular,
neural, and hormonal factors, this may be significantly affected by inflammatory
processes(absent in congenital obstruction)
Although inflammatory changes do not appear to be a major
factor in early postnatal congenital urinary obstruction but it is likely that they begin to play a
greater role with age
Congenital obstruction alters both the ongoing functional integration of the kidney as well as the
development of the mechanisms that are intrinsic to this regulation.
Ureterovesical Junction Obstruction
• Less common than UPJ-O
• Characterized by ureteral dilation along with varying degrees of renal
pelvic and calyceal dilation
• Ectopic ureter inserting into the bladder neck, or high-grade VUR
• Differentiation is made postnatally
• Cannot be definitively diagnosed on prenatal usg
• Severity of ANH is not indicative of VUR and may not be the appropriate trigger
for postnatal evaluation
• VUR diagnosed on postnatal evaluation for ANH is associated with earlier
resolution of VUR
Posterior Urethral Valves
• Diagnosis made prenatally
• Mandates prompt postnatal intervention
• Fetal USG findings
• Bilateral HUN
• Thick-walled bladder
• Dilated posterior urethra – KEYHOLE SIGN
• Dysplastic renal parenchymal changes with perinephric urinomas and
Multi Cystic Dysplastic Kidney
• Confused with U/L PUJ-O
• Multiple non - communicating cysts
• Minimal or absent renal parenchyma
• Absence of a central large cyst
Grignon USG Grading System
Grade Calyceal dilatation
• Physiological dilatation
• Normal calyces
• Slight dilatation
• Moderate dilatation
• Severe dilatation +
Etiology of PUJO
• Narrowed segment of the ureter at the PUJ:
• Adynamic segment/intrinsic narrowing:
• Incomplete development of the circular muscle fibres
• Alteration/ excessive collagen fibre
• Neuronal depletion in the proximal ureter
• Attenuated muscle bundles
• “Ostling's folds”: valvular mucosal folds
• appear at the 4th month of gestation
• due to differential growth of the ureter
• disappear with a person's linear growth
• Ureteral polyps
branching lower pole vessel
• Fibrous band
• This type of obstruction reported
to occur in up to 40% of patients
• In contrast to older children and
adults, crossing vessels are rarely
encountered in young children
with prenatally detected
PUJO - Workup
• Urine analysis and culture
• Routine hematological investigations
• Renal ultrasound – first investigation to pick up PUJO
• VCUG - to evaluate for VUR
• Nuclear Renogram - DTPA, MAG-3, MRU
• Retrograde Pyelogram
• Ideally suited as a screening study and for
following patients with known
• Classical “bear paw” appearance on US
• Highly accurate in the diagnosis of renal
• Not reliable in predicting obstruction or
providing information regarding renal
• VCUG : to rule out the presence of
VUR (13-42% infants)
• Necessary to prove that the ureter is
normal in caliber and not obstructed
before repair of PUJO is done
MAGNETIC RESONANCE IMAGING
• Gadolinium-DTPA (Gd-DTPA)
• Offers excellent anatomic resolution and soft tissue contrast
• Does not use ionizing radiation
• Gd-MRU is the only study to date that has the capability of providing
excellent morphologic detail as well as functional information
• Ability to reliably detect hydronephrosis and transition in ureteral
caliber even in nonfunctioning systems
• Cortical phase - the renal cortex
enhances vividly, differentiating
renal cortex from medulla.
• Medullary phase - medulla
enhances greater than the cortex.
• Excretory phase - excretion of
contrast medium into the collecting
system and ureters
maximum intensity projection (MIP) images
• Standardized equations and values used to determine function and
classify drainage have not yet been wholly agreed on.
• Sedation is required for most children.
• Increased costs associated with MRU and availability remains limited.
DIURETIC RENAL SCINTIGRAPHY
• Substantially low dose of radiation is absorbed (virtually zero) as
compared to contrast assisted imaging
• First radiotracer used Iodopyracet (Diodrast) in 1950’s – disadvantage
was significant hepatic uptake
• Performed after 6-8 weeks of age in infants
• Repeated after 3-6 months in infants where ultrasound shows
worsening of pelvicalyceal dilatation
DIURETIC RENAL SCINTIGRAPHY
• Differentiates between obstructive and non-obstructive
hydronephrosis and estimates relative renal function
• Hydroureteronephrosis can be obstructive or non obstructive
• Whitaker Test – standard test to differentiate obstructive and non
obstructive dilatation of renal pelvis and ureter.
• Invasive test, no information about renal function, non physiologic
DIURETIC RENAL SCINTIGRAPHY
• Diuretic renography is a non invasive test to detect obstruction
• Principle – first to demonstrate a prompt collecting system with or without
any delay in excretion
• Loop diuretic like furosemide – given at the plateau of activity in the
• > 50 % washout in a non obstructed system within 12-15 mins after diuretic
DIURETIC RENAL SCINTIGRAPHY
• Obstruction results in increase radiotracer accumulation in the pelvis
• Partial obstruction and renal insufficiency give confusing results
• 99mTc - 6 hours half life – ideal radiotracer
• Easily available, less radiation
131I – Iodohippurate
• First used in 1960’s for renal imaging
• Used to detect ureteral obstruction, quantitative and
qualitative renal function
• Not used now because of the thyroid uptake of 131I and
longer half life (7 days)
99mTc Mercaptoacetyltriglycine (MAG-3)
• First used in 1986
• Principally cleared by proximal tubular secretion
• No significant glomerular filtration
• More useful in immature or chronically insufficient kidneys
• 0.5 % hepatic uptake
• Has to be boiled for radiolabelling – practical disadvantage
• FDA approved
99mTc- Ethylenedicysteine (EC )
• Kit form available at room temperature, no need to boil
• Not FDA approved
• Preferred over DTPA in patients with deranged renal function
• Faster clearance than DTPA, results in less radiation being delivered
99mTc – Diethylenetriamine Pentaacetic Acid (DTPA)
• Available since 1970, cleared almost exclusively by glomerular
• Clearance a few percentage points less than Inulin
• Slower renal clearance (as compared to tubular agents like MAG-3)
can lead to potential problems of interpretation
• Ostruction/ no obstruction, individual renal function, filtration
fraction, and renal transit times
99mTc – Dimercaptosuccinic Acid (DMSA)
• Acts on the principle of tubular fixation
• Used primarily to evaluate renal morphology, scarring, function
• Rarely used in the evaluation of PUJO
Three parts of a given renal nuclear scan
• The images of the kidneys
• The graphical representation/curve
• The numerical values
• The images given are actually 2 sets of images
• 1st one represents the perfusion phase and images are taken at 1
image/sec after injecting contrast.
• Contrast usually reaches both kidneys simultaneously and within 5
• Thus both kidneys should be seen together after 5 second image.
• The second set of images are taken at 1 image/min and represent
intra renal transient time and excretion of contrast into PC system and
• Usually intra renal transient time (IRT) is less than 5 mins, so contrast
should be seen in PC system by 5 images.
• Delay in IRT represents obstruction.
• According to the timing of Lasix administration - 3 protocols.
• F + 20 - Furosemide is injected 20 minutes after the injection of
• F (– 15) - Furosemide is injected 15 minutes prior to the tracer.
• F – 0 - Furosemide is injected at the beginning of the study.
Pitfalls in Nuclear Scans
Significant motion can also alter the image quality.
High background activity seen in CKD and immature kidneys of infants.
Dehydration - progressive tracer accumulation within the PCS
Failure of child to hold his urine until requested
99mTc-DTPA tends to overestimate in patients with low GFR and underestimate in patients with high GFR
compared to inulin
Photopenic areas will show less function.
Indications for Intervention
Symptomatic (pain, palpable lump, hematuria, recurrent febrile UTI,
Reduction of differential renal function by more than 5- 10%
Worsening dilatation with evolving parenchymal thinning
Contralateral compensatory hypertrophy
Development of stones
• Retrograde Ureteroscopic Endopyelotomy
• Cautery wire balloon
• Improved ureteroscopic instrumentation, laser technology, and better
outcomes make ureteroscopic endopyelotomy the current retrograde
approach of choice.
• Davis Intubated Ureterotomy, first described in 1943, rarely used
• A ureterotomy is performed from at least 1 cm above the stricture to
1 cm below
• Proximal diversion established with a well-located nephrostomy tube
and a stent placed across the ureterotomy.
• Stent kept for 4 to 6 weeks.
• 70% satisfactory result
• Preferred by most urologists
• Universally applicable to the
different clinical scenarios
• Retroperitoneal approach is
• Transperitoneal if bilateral
• No need of stent if straight forward
repair in pediatric population –
avoids another GA
• Durable with long term recurrence
• For a large or redundant pelvis a
reduction pyeloplasty is
performed by excising the
redundant portion between
• Cephalad portion of pelvis is
closed with running sutures
down to the dependant portion.
• The dependant aspect of the
pelvis is then anastomosed to
the proximal ureter.
Dismembered Pyeloplasty in Crossing Vessel
• Originally described by
Hellstrom and Vahlquist.
• The technique is only feasible in
cases of anterior lower pole
accessory vessel without any
Foleys Y-V Plasty
• Best applied to a upjo with high insertion of ureter.
• The base of the V is positioned on the dependant
medial aspect of the renal pelvis and the apex at
• The incision from the apex of the flap which
represents the stem of the Y is carried along the
lateral aspect of the proximal ureteral wall into an
area of normal caliber
• The apex of the pelvic flap is brought to the most
inferior aspect of the ureterotomy incision
• The posterior walls are approximated using
interrupted or running sutures
• Anastomosis is completed with approximation of
the anterior walls of the pelvic flap and
Culp DeWeerd Spiral Flap
• Indicated for relatively long areas of proximal ureteral
obstruction when the UPJ is already in a dependent position.
• Spiral flap is outlined with Base of the flap is situated
obliquely on the dependant aspect of the renal pelvis.
• The base of the flap is positioned anatomically lateral to the
UPJ between the ureteral insertion and renal parenchyma
• The flap is spiraled posteriorly to anteriorly
• The anatomically medial line of incision is carried down
completely through the obstructed proximal ureteral
segment into normal caliber ureter
• The longer the segment of the proximal ureteral obstruction ,
the farther away the apex, to preserve vascular integrity to
the flap the ratio of flap length to width should not exceed 3
• Once the flap is developed the apex is rotated down to the
most inferior aspect of the ureterotomy
• Anastomosis is completed over an internal stent using fine
Scardino Prince Vertical Flap
• Used when a dependant ureteropelvic
junction is situated at the medial margin of a
large , box shaped extrarenal pelvis
• The base of the flap is situated more
horizontally on the dependent aspect of the
renal pelvis between the UPJ and renal
• The flap is formed by two straight incisions
converging from the base vertically upto the
apex on either anterior or posterior aspect of
• The apex of the flap is rotated down to the
most inferior aspect of the ureterotomy
• The flap is closed by approximating the edges
with interrupted or running sutures
• The ureter is identified in the retroperitoneum and dissected proximally as far as possible
• The kidney is mobilised to gain access to the lower pole and perform anastomosis
• Lower pole nephrectomy is performed to expose a dilated lower pole calyx
• Proximal ureter is spatulated laterally
• Anastomosis is performed over a stent
• Initial suture is placed at the apex of the ureteral spatulation and the lateral wall of the
calyx with another suture placed 180 degrees from the first suture
• Anastomosis is completed in an open fashion placing each suture circumferentially but
not securing them until the anastomosis has been completed
• Renal capsule is closed over the cut surface of the parenchyma
• The anastomosis should be protected with a graft of perinephric fat or with a peritoneal
or omental flap
Endopyelotomy - Basics
• Endopyelotomy was coined by Badlani et al. (1986)
• Full-thickness lateral incision through the obstructing proximal ureter,
from the ureteral lumen out to the peripelvic and periureteral fat.
• Double J stent in kept in place for 6 weeks
• Based on the original work of Davis in 1943, who performed an
“intubated ureterotomy” to repair UPJO
• Antegrade of retrograde approach
• Holmium laser/ cold knife (straight or hooked)/ electrocautery/
balloon with a cutting wire (Acucise) /Balloon dilation and rupture
• Invagination Technique
• Percutaneous Endopyeloplasty
• Reduced hospital stay
• Early postoperative recovery
• Concomitant stones can be dealt in the same sitting
• Transplantation complications are particularly suited to
endoscopic management, either antegrade or retrograde
• High failure rates in crossing vessels
• Urine leakage
• The success rate does not approach that of open,
laparoscopic, or robotic pyeloplasty.
Cold Knife Endopyelotomy
Vaarala et al. (2008) reported a small series of 64 patients who
underwent either antegrade or retrograde cold knife or cautery wire
balloon endopyelotomy. In this study, success rates ranged from 79% to
83%, without statistically significant differences among the three
• The UPJ is first inspected for the presence of any transmitted
• Incised laterally, between 8 and 9 o’clock on the right and between 3
and 4 o’clock on the left.
• Short and shallow strokes performed
• Any bleeding site is controlled by means of spot electrocoagulation
Cautery Wire Balloon Endopyelotomy
• Under fluoroscopic guidance the Acucise
catheter (6Fr) is advanced over a guide wire
up to the UPJ.
• 10/24 Fr low‐pressure balloon (3cm)
• The balloon is gently inflated with 0.5 ml
diluted contrast medium to ensure correct
• Active wire is directed laterally
• The cutting wire is activated at 75–100 W
(pure cutting power) for 5 seconds
• Simultaneously 2 ml diluted contrast medium is instilled into the dilating
• As the balloon inflates, the stricture is incised
• The balloon is kept inflated for 10 min to tamponade the incision site.
• Retrograde pyelography is performed to confirm extravasation at the
• 14-7 Fr endopyelotomy or regular 7 Fr Double-J stent is kept for 6 weeks
• Provides similar long-term success rates as compared to holmium laser
Endoburst - Balloon dilation and rupture
• Retrograde access - 24–30 Fr angioplasty balloon is inserted over a
guidewire and positioned across the UPJ under fluoroscopic control.
• The balloon is inflated until wasting completely disappears.
• Several inflation/deflection cycles are recommended in order to
ensure that no residual narrowing remains.
• Long‐term success with this technique has been inferior to that with
Retrograde Ureteroscopic Endopyelotomy
• Can be traced back to the original descriptions of Albarran, Keyes, and
• Both the antegrade and retrograde endopyelotomy follow the
concept of Davis’s intubated ureterotomy, first described by Davis in
• Wickham and Kellet described the first ureteroscopic pyelolysis of the
UPJ in 1983
• First reported in 1985 - Bagley et al reported a combined
percutaneous and flexible ureteroscopic procedure.
• Advantages - allows direct visualization of the UPJ
- no need for percutaneous access
- patient compliance, less morbidity
- more cost effective than balloon endopyelotomy,
antegrade endopyelotomy, and pyeloplasty
• Disadvantages – distal ureteric stricture
concomitant stone disease
• 200 μm flexible ureteroscope
• 365 μm semirigid ureteroscope
• Setting of 1.5 to 2.5 J and a frequency of
10 to 15Hz
• UPJ is incised laterally upto the peripelvic
and periureteral retroperitoneal space.
• As performed under direct vision, any
visualized vessels and significant bleeding
is usually avoided.
• Less is known.
• The original report and
recommendation of 6 weeks by
Davis (1943) is still used
• Mandhani et al. (2003) -
identified no difference in
results when comparing 57
patients stented for 2 weeks
versus 4 weeks.
• Although the need for
while the stent is indwelling
is not literature based, many
use a daily suppressive dose.
• 1st follow up at 1 month for clinical and radiographic evaluation.
• Includes history, physical examination, urinalysis, and diuretic renography.
• If normal - reevaluation is performed at 6 months and then at 12 month
• Majority of failures occur within the first year of the procedure
• 2-3 year follow up is justified because studies indicate that even at 36
months some late failures are identified, but relatively few are identified at
• First described by Gelet and colleagues
• Balloon is inflated below the UPJ.
• After percutaneous access - the inflated balloon is grasped from
above and pulled inside the renal pelvis, invaginating the UPJ and
• Holmium laser or electrocautery used to incise the double tissue layer
down to the plastic balloon.
• If residual narrowing is suspected - balloon is reinflated on its way
out to calibrate the ureter.
• Spontaneous reduction of the invagination occurs when the
balloon is deflated.
• Rest of the procedure same as other techniques
• Advantages - UPJ is stabilized on the dilated balloon
- reduces the risk of damaging crossing vessels
• 5 mm suturing instrument used for
placing interrupted sutures
• Can be inserted through working
channel of a 26-French Storz
• A 30-French Amplatz sheath is
positioned after poercutaneous
• Conventional endopyelotomy
• First described in 2002
• Stein et al. (2007) reported 55 patients with short term follow up with
more than 90% success.
• May not be effective for secondary UPJO because tissue scarring may
inhibit the endoscopic reconstruction.
• Lezrek et al (2012) reported a modified technique requiring no specialized
equipment ( 3.5 mm laparoscopic needle holders and a nephroscope) in 10
• Pelviureteric junction obstruction (PUJO) of the kidney can lead to a
number of different clinical manifestations, which often require surgical
• Although the success of pyeloplasty and endopyelotomy are good, there
are still a number of patients who fail primary treatment and develop
• These treatment failures can be a challenging cohort to manage.
• Failure can be considered as the inability to improve symptoms, dynamic
renographic parameters, renal unit function or hydronephrosis.
The causes of failed treatment include :
Poor surgical technique
Irreparable pelvi-caliceal system
PUJ ischemia with re-stenosis
Anastomotic leak with urinoma and fibrosis
Missed crossing vessel in 18%-50% of cases,
Ureteric stent malfunction and diabetes.
Most treatment failures present within the first 18 months following the
However, secondary PUJO has been identified in patients up to 5 years after
• There are a number of options available to the clinician for management of
• The best option for the patient will depend on numerous factors including;
Individual upper tract anatomy,
Presence of renal calculi,
Concurrent medical conditions,
Informed patient preference,
Availability and experience of individual techniques,
Symptoms, renal function and the type of primary treatment modality.
A variety of mediators of EMT have been described, including
1.transforming growth factor-β (TGF-β),
4.inhibitors, such as hepatocyte growth
Although inflammatory changes do not appear to be a major
factor in early postnatal congenital urinary obstruction it is likely that they begin to play a greater role with age.
Inflammatory mediators such as
monocyte chemoattractant protein-1 (MCP-1),
tumor necrosis factor-α (TNF-α),
Regulated on activation normal T-cell expressed and secreted (RANTES),
For a large or redundant pelvis a reduction pyeloplasty is performed by excising the redundant portion between traction sutures. Cephalad portion of pelvis is closed with running sutures down to the dependant portion. The dependant aspect of the pelvis is then anastomosed to the proximal ureter.
Originally described by Hellstrom and Vahlquist.
The technique is only feasible in cases of anterior lower pole accessory vessel without any intrinsic pujo
Best applied to a upjo with high insertion of ureter.
The base of the V is positioned on the dependant medial aspect of the renal pelvis and the apex at the upj
The incision from the apex of the flap which represents the stem of the Y is carried along the lateral aspect of the proximal ureteral wall into an area of normal caliber
The apex of the pelvic flap is brought to the most inferior aspect of the ureterotomy incision
The posterior walls are approximated using interrupted or running sutures
Anastomosis is completed with approximation of the anterior walls of the pelvic flap and ureterotomy.
Indicated for relatively long areas of proximal ureteral obstruction when the UPJ is already in a dependent position.
Spiral flap is outlined with Base of the flap is situated obliquely on the dependant aspect of the renal pelvis.
The base of the flap is positioned anatomically lateral to the UPJ between the ureteral insertion and renal parenchyma
The flap is spiraled posteriorly to anteriorly
The anatomically medial line of incision is carried down completely through the obstructed proximal ureteral segment into normal caliber ureter
The longer the segment of the proximal ureteral obstruction , the farther away the apex, to preserve vascular integrity to the flap the ratio of flap length to width should not exceed 3 to 1
Once the flap is developed the apex is rotated down to the most inferior aspect of the ureterotomy
Anastomosis is completed over an internal stent using fine absorbable sutures
Used when a dependant ureteropelvic junction is situated at the medial margin of a large , box shaped extrarenal pelvis
The base of the flap is situated more horizontally on the dependent aspect of the renal pelvis between the UPJ and renal parenchyma
The flap is formed by two straight incisions converging from the base vertically upto the apex on either anterior or posterior aspect of renal pelvis
The apex of the flap is rotated down to the most inferior aspect of the ureterotomy
The flap is closed by approximating the edges with interrupted or running sutures
The ureter is identified in the retroperitoneum and dissected proximally as far as possible
The kidney is mobilised to gain access to the lower pole and perform anastomosis without tension
Lower pole nephrectomy is performed to expose a dilated lower pole calyx
Proximal ureter is spatulated laterally
Anastomosis is performed over a stent
Initial suture is placed at the apex of the ureteral spatulation and the lateral wall of the calyx with another suture placed 180 degrees from the first suture
Anastomosis is completed in an open fashion placing each suture circumferentially but not securing them until the anastomosis has been completed
Renal capsule is closed over the cut surface of the parenchyma
The anastomosis should be protected with a graft of perinephric fat or with a peritoneal or omental flap