This document discusses the etiopathogenesis, clinical features, and diagnosis of ureteropelvic junction (UPJ) obstruction. It begins by defining UPJ obstruction as a restriction of urine flow from the renal pelvis to the ureter. UPJ obstruction can be caused by intrinsic factors like anatomical abnormalities or extrinsic factors like crossing vessels. Clinically, it can present at any age as flank pain, hematuria, or hypertension. Diagnosis involves imaging like renal ultrasound, CT urogram, diuretic renogram, and voiding cystourethrogram to evaluate obstruction and identify associated issues like vesicoureteral reflux. Surgical correction may be needed to repair the obstruction and preserve

1. ETIOPATHOGENESIS, CLINICAL
FEATURE AND DIAGNOSIS OF PUJO
Dept of Urology
Govt Royapettah Hospital and Kilpauk Medical College
Chennai
1

2. Moderators:
Professors:
• Prof. Dr. G. Sivasankar, M.S., M.Ch.,
• Prof. Dr. A. Senthilvel, M.S., M.Ch.,
Asst Professors:
• Dr. J. Sivabalan, M.S., M.Ch.,
• Dr. R. Bhargavi, M.S., M.Ch.,
• Dr. S. Raju, M.S., M.Ch.,
• Dr. K. Muthurathinam, M.S., M.Ch.,
• Dr. D. Tamilselvan, M.S., M.Ch.,
• Dr. K. Senthilkumar, M.S., M.Ch.
Dept of Urology, GRH and KMC, Chennai. 2

3. • 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
3
Dept of Urology, GRH and KMC, Chennai.

4. PUJ Obstruction
• Accounts for 64% of infants with unresolved post-natal
hydronephrosis
• Males > Females (2:1 in newborns)
• Left >Right (2:1)
• 10% bilateral
Synchronous or asynchronous
May be inheritable
4
Dept of Urology, GRH and KMC, Chennai.

5. ETIOLOGY
• The precise cause of UPJ obstruction remains
elusive despite investigation along a number
of lines:
• ? embryologic
• ? anatomic
5
Dept of Urology, GRH and KMC, Chennai.

6. ETIOLOGY
• Intrinsic
– Aperistaltic segment
– Intrinsic narrowing/ Kink
found more frequently in the presence of renal ectopia
or fusion anomalies
– Ostling’s folds
• Present in 92% newborns
• Result from differential growth of ureter vs body
• Usually resolves in childhood
Ureteral polyps
Persistent fetal convolutions
6
Dept of Urology, GRH and KMC, Chennai.

7. • Transforming growth factor-β, Epidermal
growth factor expression, and Neuropeptide Y
increased UPJ stenosis
• Abnormalities of ureteral musculature have
been implicated as electron microscopy has
demonstrated excessive collagen deposition at
the site of the pujo
7
Dept of Urology, GRH and KMC, Chennai.

8. Intrinsic Cause of UPJO: Intrinsic
Narrowing
Renal Pelvis
Proximal Ureter
Intrinsic
Narrowing
8
Dept of Urology, GRH and KMC, Chennai.

9. Ureteral Polyps
9
Dept of Urology, GRH and KMC, Chennai.

10. ETIOLOGY
• Extrinsic
– High insertion
– Kinking secondary to fibrosis
– Crossing vessel ?
• 15-63%
• Anterior to UPJ supplying lower pole of kidney
• Majority in adults or older children
10
Dept of Urology, GRH and KMC, Chennai.

11. • When an aberrant or accessory renal artery to the lower
pole of the kidney is present and the ureter courses behind
it, the ureter may angulate at both the UPJ and the point at
which it traverses over the vessel as the pelvis fills and
bulges anteriorly.
• Further angulation of the ureter occurs as it becomes
adherent to the PUJ secondary to an inflammatory process
• A two-point obstruction ensues, with kinking of the ureter
at the PUJ and at the point where the ureter drapes over
the vessel.
• Over time, these areas may become ischemic, fibrotic, and
finally stenotic
• Secondary UPJ obstruction due to severe VUR
11
Dept of Urology, GRH and KMC, Chennai.

12. Lower Pole Vessel
UPJ Anterior
High Insertion Kinking
Crossing Vessels 12
Dept of Urology, GRH and KMC, Chennai.

13. EXTRINSIC CAUSE
• Fibroepithelial polyps
• Urothelial malignancy,
• Stone disease
• Postinflammatory or postoperative scarring or
ischemia
13
Dept of Urology, GRH and KMC, Chennai.

14. PATHOLOGIC CHANGES OF
OBSTRUCTION
GROSS
• kidneys - enlarged, cystic
appearance
• Dilation of the pelvis and
ureter and blunting of the
papillary tips
• Cortex edematous & slightly
enlarged
• diffuse thinning of cortex
and medullary tissue
MICROSCOPIC
• Widespread glomerular
collapse and tubular
atrophy, interstitial fibrosis,
and proliferation of
connective tissue in the
collecting system --- 5 to 6
weeks after obstruction
14
Dept of Urology, GRH and KMC, Chennai.

15. SCLEROSIS & HYALINOSIS OF
GLOMERULUS TUBULES DEMONSTRATE
THYROIDIZATION-TYPE ATROPHY
15
Dept of Urology, GRH and KMC, Chennai.

16. Patterns of Effect
• 1. regulation of growth,
• 2.tissue differentiation,
• 3.fibrosis
• 4.altering the functional integration of the
kidney
16
Dept of Urology, GRH and KMC, Chennai.

17. 17
Dept of Urology, GRH and KMC, Chennai.

18. Differentiation
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.
Abnormal epithelial mesenchymal transformation (EMT) is one
alteration in differentiation that does occur in the adult and can
be reversible 18
Dept of Urology, GRH and KMC, Chennai.

19. FIBROSIS
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 collagens, fibronectin, and
other connective tissue proteins.
Their presence disrupts the normal interconnections
between cells that permit functional integration of the
renal tissues.
19
Dept of Urology, GRH and KMC, Chennai.

20. TUBULOINTERSTITIAL FIBROSIS
20
Dept of Urology, GRH and KMC, Chennai.

21. • 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 than at present
• 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
21
Dept of Urology, GRH and KMC, Chennai.

22. FUNCTIONAL INTEGRATION
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.
22
Dept of Urology, GRH and KMC, Chennai.

23. CLINICAL FEATURE
• Can present clinically at any time of life.
• Asymptomatic
• The most common presentation in neonates and
infants palpable flank mass
• During evaluation of azotemia, which may result
from bilateral obstruction in a functionally or
anatomically solitary kidney.
• UPJ obstruction may also be incidentally found
during studies performed to evaluate unrelated
anomalies such as congenital heart disease
23
Dept of Urology, GRH and KMC, Chennai.

24. • In older children or adults, intermittent abdominal
or flank pain, at times associated with nausea or
vomiting,
• Hematuria, either spontaneous or associated with
otherwise relatively minor trauma,
• Laboratory findings of microhematuria, pyuria, or
frank urinary tract infection
• Hypertension
24
Dept of Urology, GRH and KMC, Chennai.

25. UPJ Obstruction-Workup
• Renal Ultrasound
• CT UROGRAPHY
• Diueretic Renogram
– Differential function
– Drainage curve
• VCUG to evaluate for VUR
– Is it needed in all children?
– Are prophylactic antibiotics needed?
• Retrograde Pyelogram
– Evaluation for distal obstruction
• If no dilated ureters on US
• On table antegrade nephrostogram
25
Dept of Urology, GRH and KMC, Chennai.

26. Antenatal Hydronephrosis
Society for Fetal Urology Grading System
Grade 0:no hydronephrosis
Grade 1:slight pelvic dilatation,no calyceal
dilatation
Grade 2: moderate pelvic dilatation,slight
calyceal dilatation(major calyces)
Grade 3: large pelvis, dilated calyces (minor
calyces),normal parenchyma
Grade 4: large pelvis, dilated calyces,thinned
parenchyma
26
Dept of Urology, GRH and KMC, Chennai.

27. Normal Kidney
(SFU Grade 0)
SFU Grade 1
(Pelviectasis)
27
Dept of Urology, GRH and KMC, Chennai.

28. Hydronephrosis Grades 2 and 3
From www.cevlforhealthcare.org
28
Dept of Urology, GRH and KMC, Chennai.

29. SFU Grade 4
(Thin Parenchyma)
29
Dept of Urology, GRH and KMC, Chennai.

30. Timing of Ultrasound
Initial 3 Month Ultrasound
30
Dept of Urology, GRH and KMC, Chennai.

31. VCUG
• Voiding Cystourethrogram
• Evaluate vesicoureteral reflux and male
urethra
31
Dept of Urology, GRH and KMC, Chennai.

32. Imaging: Renograms
• DMSA (Technetium-99m-dimercaptosuccinic acid)
– Tightly bound to renal tubular cells
– Excellent renal cortical imaging agent
– No interference from the collection system
– Good for acute pyelonephritis and cortical scars
– Most accurate to determine differentialrenal function
• DTPA (Technetium-99m-diethylenetriamine pentaacetic acid)
– Clearance exclusively via GF
– No significant tubular secretion or cortical retention
– Good for renal perfusion and GFR determination
• MAG-3 (Technetium-99m-mercaptoacetyltriglycine)
– Clearance by tubular secretion
– Good for renal perfusion and drainage studies
– Higher renal extraction fraction vs DTPA
– Superior image quality versus DTPA
– More accurate in settings of immature renal function 32
Dept of Urology, GRH and KMC, Chennai.

33. Diuretic Renogram
1. Differential renal function (DRF)
– Measured prior to renal excretion (2 min)
• Influenced by timing of diuretic administration
– Measurement of renal uptake subtracting for background
• Sometimes difficult in hydronephrotic kidney
2. t1/2 time
– Defined as the time for the radionucleotide to decrease by half
the peak amount in the pelvis
– Generation of a time drainage curve
• >20 min “obstructed”
• 10-20 min indeterminant
• <10 min unobstructed
33
Dept of Urology, GRH and KMC, Chennai.

34. Diuretic Renogram
34
Dept of Urology, GRH and KMC, Chennai.

35. Diuretic Renograms-Variability
• Hydration State
• Functional status of the kidney
• Renal responsiveness to diuretic
• Bladder fullness
• Operator dependency
– Timing of diuretic administration
– Area of interest
• Postural positioning during imaging
• Collecting system capacity / compliance
35
Dept of Urology, GRH and KMC, Chennai.

36. Magnetic Resonance Urogram
• Newest technology
• Use of Gd-DTPA and Lasix
• T1 and T2 weighted images
• Measurement of GFR and Renal Transit Time (RTT)
• Better anatomical detail and better predictor of UPJ
obstruction
• Expensive and not widely available
• Requires sedation
36
Dept of Urology, GRH and KMC, Chennai.

37. • MRU measurement of contrast excretion is the renal transit
time, which is defined as the time it takes for contrast to pass
from the renal cortex to the proximal ureters
• normal 4 minutes or less
• Equivocal if longer than 4 and less than 8 minutes
• obstructed if 8 minutes or longer
37
Dept of Urology, GRH and KMC, Chennai.

38. Whitaker Test
• 22 gauge angiocaths in
renal pelvis
• Foley catheter
• If opening pressure
normal, infuse based on
wt, ht, and age
38
Dept of Urology, GRH and KMC, Chennai.

39. Whitaker Test
• Infusion rate 10 ml/min
>22 cm H2O Obstructed
15-22 cm H2O Indeterminant
<15 cm H2O Unobstructed
39
Dept of Urology, GRH and KMC, Chennai.

40. Associated Anomalies
• Congenital renal malformations are commonly seen in association
with UPJ obstruction
• UPJ obstruction is the most common anomaly encountered in the
opposite kidney; it occurs in 10% to 40% of cases.
• Renal dysplasia and multicystic dysplastic kidney are the next most
frequently observed contralateral lesions .
• unilateral renal agenesis has been noted in almost 5% of children
• UPJ obstruction may also occur in either the upper or the lower
half (usually the latter) of a duplicated collecting system or of a
horseshoe or ectopic kidney
40
Dept of Urology, GRH and KMC, Chennai.

41. THANK YOU
41
Dept of Urology, GRH and KMC, Chennai.