This document provides an overview of the approach to congenital hydronephrosis. It defines hydronephrosis and describes the most common causes including physiologic hydronephrosis, UPJ obstruction, UVJ obstruction, VUR, Eagle-Barrett Syndrome, PUV, and MCDK. It discusses grading of fetal and neonatal hydronephrosis using RPD, SFU criteria, and UTD classification system. The document outlines the approach including physical exam, imaging studies like VCUG and diuretic renography to diagnose underlying causes and guide treatment.

1. Approach to congenital
Hydronephrosis
Presesented by-Dr.Santhosh Reddy
Moderator – Dr.Arnab Senguptha

2. Overview
• Definition and etiology
• Grading of fetal and neonatal hydronephrosis
• Approach to hydronephrosis
• Fetal
• Neonatal

3. • Hydronephrosis:
• Dilation of the renal pelvis with or without dilation of the renal calyces

5. • Physiologic Hydronephrosis At least 80% of all prenatally detected mild
hydronephrosis (APRPD 7-10 mm at 30 weeks’ gestational age) resolves
spontaneously and is not associated with an anatomic abnormality of the urinary
tract.
• Hydronephrosis, which improves or resolves during the pregnancy, is unlikely to
have any postnatal implications.
• Physiologic hydronephrosis may be caused by a delay in the maturation of the
ureter, which leads to transient urinary flow obstruction.
• The hydronephrosis in these patients generally resolves within the first 2 years of
life.

6. • Ureteropelvic Junction Obstruction -UPJ obstruction is the most common cause
of moderate to severe congenital hydronephrosis and may be the result of
incomplete recanalization of the proximal ureter, abnormal development of the
ureteral musculature, abnormal peristalsis, or polyps.
• UPJobstruction is more common in boys and may be associated with other
congenital anomalies (including other genitourinary malformations) or
syndromes. The diagnosis is confirmed by an obstructive pattern observed on a
diureticenhanced radionuclide scan,
• antibiotic prophylaxis to prevent urinary tract infection, which was shown to be
effective in preventing infection in patients with high-grade hydronephrosis.
Temporary relief of obstruction may be necessary and is often achieved by
placement of a percutaneous nephrostomy drain. Definitive treatment often
involves surgical repair
• About 20%-25% of children with UPJ obstruction will have surgery for
decreased renal function or progressionof hydronephrosis.

7. • Ureterovesical Junction Obstruction-UVJ obstruction is another cause of
congenital hydronephrosis and is characterized by hydronephrosis with
associated ureteral dilatation.
• This disorder may be related to the deficient development of the distal ureter or
the presence of a ureterocele and is likely to spontaneously resolve in 70% of
patients.
• The diagnosis is confirmed by a radionuclide scan and VCUG. UVJ obstruction is
usually not associated with other congenital malformations.
• A ureteral dilation greater than 1 cm is associated with higher risk of urinary tract
infection so antibiotic prophylaxis may be indicated.
• Temporary or permanent surgical interventions may be required, based on the
clinical situation.

8. • Vesicoureteral Reflux - VUR accounts for 10%-40% of neonatal hydronephrosis.
• It is defined as the retrograde propulsion of urine into the upper urinary tract
during bladder contraction.
• The underlying cause of VUR is believed to be ectopic insertion of the ureter into
the bladder wall, resulting in a shorter intravesicular ureter, which acts as an
incompetent valve during urination. Vesicoureteral reflux is graded from I to V,

9. • Eagle-Barrett Syndrome - Eagle-Barrett (“prune belly”) syndrome (EBS) is
characterized by a triad of
• genitourinary abnormalities (markedly enlarged bladder with poor contractility
without urethral obstruction, megaureters, and renal dysplasia),
• deficiency of abdominal wall musculature, and
• cryptorchidism .
• The estimated incidence is 1 in 35,000-50,000 live births, with more than 95% of
the cases occurring in boys.

10. • Posterior urethral valves (PUV) represent the most common cause of lower
urinary tract obstruction, with an incidence of 1 in 5000-8000 live male births.
• A posterior urethral valve is composed of a congenital membrane that obstructs
• or partially obstructs the posterior urethra and is formed when the mesonephric
duct fails to adequately regress.
• Findings on prenatal ultrasound may include hydronephrosis; dilated ureters; a
thickened, trabeculated bladder; dilated proximal urethra; and oligohydramnios.
The antenatal presentation may include a palpable, distended bladder, poor
urinary stream, and signs and symptoms of renal and pulmonary insufficiency.
• The VCUG is diagnostic for PUV and reveals associated VUR in 30% of patients

11. • Multicystic Dysplastic Kidney - Multicystic dysplastic kidney MCDK represents the
most severe form of renal dysplasia and is characterized by a nonfunctioning
kidney that is devoid of normal renal architecture and composed of multiple large
cysts that resemble a cluster of grapes
• About 20% of children with unilateral MCDK will have vesicoureteral reflux into
the contralateral kidney, which is grades I-III in 96%.

12. Grading
• Renal pelvic diameter (RPD)
• Society of Fetal Urology (SFU) criteria
• Urinary tract dilation (UTD) classification system

13. Renal pelvic diameter (RPD)
• The most generally accepted method to define and grade fetal hydronephrosis is
measurement of the maximum APPD, also referred to as RPD, in the transverse
plane .
• Fetal hydronephrosis is graded according to the RPD during the second and/or
third trimester of pregnancy.
• RPD is a measure of collecting system dilation and does not reflect the extent of
hydronephrosis and parenchymal changes, such as increased echogenicity,
thinning, or caliectasis.
• Indian J Nephrol. 2013 Mar-Apr; 23(2): 83–97.Revised guidelines on management of antenatal
hydronephrosis A. Sinha, A. Bagga,et al.

14. Descriptive definition of hydronephrosis by
Antero Posterior Diameter.
Classification of
hydronephrosis
Second trimesterAPD in
mm
Third trimesterAPD in
mm
Mild 4-6 7-9
Moderate 7-10 9-15
Severe > 10 > 15

15. Society of Fetal Urology (SFU)
• The SFU developed criteria for the diagnosis and grading of fetal hydronephrosis
based upon the
• degree and site of pelvic dilation,
• number of calyces seen, and
• the presence and severity of parenchymal atrophy .
• The SFU grading system focuses on the degree of hydronephrosis in the kidney
without directly assessing the state of the ureter and bladder:
• Indian J Nephrol. 2013 Mar-Apr; 23(2): 83–97.Revised guidelines on management of antenatal
hydronephrosis A. Sinha, A. Bagga,et al.

17. Urinary tract dilation (UTD) classification system
• The UTD classification system is based on six ultrasound findings and is
stratified based on GA and whether the detection is antenatal or postnatal
• Anterior and posterior RPD
• Calyceal dilation
• Renal parenchymal thickness
• Renal parenchymal appearance
• Bladder abnormalities
• Ureteral abnormalities
• Journal of pediatric urology 2014,10,982-999, Multidisciplinary consensus on the classification of prenatal
and postnatal urinary tract dilation (UTD classification system) Hiep T. Nguyen et al.

18. UTD A1 : APPD; 16 to 27 weeks: 4 mm to <7 mm
≥ 28 weeks: 7 mm to <10 mm
With or without central calyceal dilatation
UTD A2-3 : APPD; 16 to 27 weeks: ≥7 mm
≥28 weeks: ≥10 mm
Peripheral calyceal dilatation
Abnormal parenchyma thickness or appearance
Abnormal ureter or bladder
Unexplained oligohydramnios

19. UTD P1 (low risk) : APPD 10 mm to <15 mm
Central calyceal dilatation
UTD P2 (intermediate risk) : APPD ≥15 mm
Peripheral calyceal dilatation
Abnormal ureter
UTD P3 (high risk) : APPD ≥15 mm
Peripheral calyceal dilatation
Abnormal parenchymal thickness or appearance
Abnormal ureter
Abnormal bladder

20. Physical examination
• The neonatal physical examination can identify abnormalities that are indicative of
congenital anomalies of the kidney and urinary tract (CAKUT), which are associated
with fetal hydronephrosis. These include the following:
• Abdominal mass - enlarged kidney due to obstructive uropathy or multicystic
dysplastic kidney
• A palpable bladder in a male infant- posterior urethral valves (PUV).
• A male infant with deficient abdominal wall musculature and undescended testes-
prune-belly syndrome
• outer ear abnormalities - associated with an increased risk of CAKUT.
• A single umbilical artery - increased risk of CAKUT, particularly vesicoureteral reflux
(VUR).
• Spinal and/or lower extremity abnormalities suggesting a neurogenic bladder, which
may result in hydronephrosis and dilated ureters

21. Imaging studies
• USG
• Voiding cystourethrogram
• Diuretic renography
• Magnetic resonance urography

22. Voiding cystourethrogram
• VCUG is performed in the majority of neonates with
persistent postnatal hydronephrosis (RPD ≥10 mm) to identify patients with
bladder outlet obstruction, most commonly PUV,VUR
• MCU be performed in patients with unilateral or bilateral hydronephrosis with
renal pelvic APD > 10 mm, SFU grade 3-4 or ureteric dilatation .
• MCU be performed early, within 24-72 h of life, in patients with suspected lower
urinary tract obstruction . In other cases, the procedure should be done at 4-6
weeks of age.
• MCU done for infants with antenatally detected hydronephrosis who develop a
urinary tract infection

26. • MCU is also required in patients with history of milder grades of ANH who show
worsening hydronephrosis, progressive parenchymal thinning or occurrence of
UTI.

27. Diuretic renography
• Diuretic renography is used to diagnose urinary tract obstruction in infants with
persistent grade 4 and possibly grade 3 hydronephrosis after a VCUG has demonstrated
no VUR .
• It measures the drainage time from the renal pelvis, and assesses the relative
contribution of each kidney to overall renal function.
• The test requires insertion of a bladder catheter to relieve any pressure that can be
transmitted to the ureters and kidneys.
• Intravenous access is needed for hydration and the administration of the radioisotope
and diuretic.
• The preferred radioisotope is technetium-99m-mercaptoacetyltriglycine (Tc99mMAG3),
which is taken up by the renal cortex, filtered across the glomerular basement
membrane (GBM) to the renal tubules, and excreted into the renal pelvis and urinary
tract.
• Journal of pediatric urology VOLUME 15, ISSUE 2, P128-137, APRIL 01, 2019,Diuresis renography in the
evaluation and management of pediatric hydronephrosis: C.E. Bayne et al.

28. • Infants with moderate to severe unilateral or bilateral hydronephrosis (SFU grade
3-4, APD >10 mm) who do not show VUR should undergo diuretic renography.
• Infants with hydronephrosis and dilated ureter(s) and no evidence of VUR
undergo diuretic renography.
• Diuretic renography be performed after 6-8 weeks of age.
• The procedure may be repeated after 3-6 months in infants where ultrasound
shows worsening of pelvicalyceal dilatation

29. • Cortical retention of tracer due to acute left UPJ obstruction

30. Magnetic resonance urography
• Magnetic resonance urography (MRU) in children is becoming more commonly
used in the diagnosis and management of congenital uropathies, such as
ureteropelvic junction obstruction (UPJO) .
• MRU is especially useful in the management of obstructed kidneys that have
rotation or ascent anomalies, or are single.
• MRU can more clearly define the anatomy and delineate the proper surgical
approach (ie, retroperitoneal versus transperitoneal).

31. • The disadvantage of MRU is that the study often requires general anesthesia or
heavy conscious sedation in children.
• However, for patients in the newborn period, many centers are now performing
"swaddle MRI" after the infant falls asleep after feeding, thus avoiding general
anesthesia and conscious sedation.
• Another disadvantage is the use of the contrast agent gadolinium, which can only
be used if the renal function is normal (requiring a preprocedure serum
creatinine test) because of reports of irreversible renal fibrosis in patients with
renal insufficiency

32. • MR urography showing left PUJ obstruction

33. Perform postnatal ultrasound of KUB region;
Within 24-48 hours of birth if LUTO
Between 3-7 days in other cases confirmed
postnatally
No
hydronephrosis(SFU
grade 0&APD <7mm
Unilateral or bilateral
hydronephrosis and
LUTO unlikely
Features of LUTO
Management of antenatal hydronephrosis

34. • Repeat USG at 4-6weeks
• Normal USG abnormal
• No further work up required
No hydronephrosis(SFU grade
0&APD <7mm

35. •
• SFU grade 1&2 or APD <10 mm and SFU grade 3 &4 or APD >10 and
Normal ureter ureter dilated
• USG monotoring at 4-6 wk, MCU at 4-6 weeks
then every 6-12 months till resolution
Normal VUR present
RDS at 6-8 weeks Antibiotic
prophylaxis
Unilateral or bilateral hydronephrosis and LUTO unlikely

36. Renal dynamic scan at 6-8 weeks
• Non obstructive pattern;USG Obstructive pattern with differential
moniring till resolution function<40%: consider pyeloplasty
• Persistence or worsening : antibiotic prophylaxis
Repeat RDS

37. MCU within 48 hours
LUTO absent LUTO present
VUR present Refer to pediatric surgeon
Give antibiotic prophylaxis
Features of LUTO

38. Emergency Measures to be taken within first 48 h after birth
in infants diagnosed with antenatal hydronephrosis.
USG
Suspected lower tract obstruction, e.g., Posterior urethral
valves, prune belly syndrome
Bilateral hydronephrosis with or without hydroureter
Solitary kidney with APD > 15 mm or SFU grade 2 or more
Antibiotic prophylaxis
Suspected lower tract obstruction
APD > 10 mm or SFU grade 2 or more in the third trimester
Solitary kidney with hydronephrosis of any grade
Bilateral hydronephrosis
VCUG Suspected posterior urethral valves antenatally
Catheterization
Suspected lower tract obstruction-posterior urethral valve or
prune belly syndrome

39. NON EMERGENCY POST NATAL MANAGEMENT
• Since infants are relatively dehydrated at birth, the initial postnatal
ultrasonography should be performed after 48 h of birth.
• Also breast fed neonates may not be adequately hydrated until a steady milk flow
is established.
• Hence the first postnatal ultrasound is preferably done between 3-7 d after birth.

40. Ultrasonography at 5-7 d would show one of the following scenarios:
• No hydronephrosis-Normal pelvicalyceal system;
• Unilateral hydronephrosis;
• Bilateral hydronephrosis;
• Unilateral Hydronephrosis with hydroureter; and
• Bilateral hydronephrosis with bilateral hydroureter

41. • ANH carries a significant risk of a postnatal pathologic outcome
• Mild –88.3%
• Moderate-45.9%
• Severe-11.9%
• Continuous prophylaxis cephalexin 10 mg/kg/d HS,
• Trimethoprim 1-2 mg/kg/d HS,
• Nitrofurantoin 1-2 mg/kg/d HS
• Counsel parents regarding increased risk of urinary tract infections due to VUR ,perform urine
culture for any fever without focus.
• Pediatrics office journal of the american academy of pediatrics Antenatal Hydronephrosis as a
Predictor of Postnatal Outcome: A Meta-analysis Richard S. Lee et al. Pediatrics August 2006,

42. Indications for surgery
• obstructive pattern on diuretic renography and differential function exceeding
40%.
• infants with lower urinary tract obstruction
• obstructed hydronephrosis, and either reduced differential renal function or its
worsening on repeat evaluation
• bilateral hydronephrosis or hydronephrosis in solitary kidney showing worsening
dilatation and deterioration of function.
• Other indications for surgery include
• presence of pain,
• palpable renal lump or
• recurrent febrile UTI.

43. References
• World J Clin Urol. Nov 24, 2014; 3(3): 283-294
Published online Nov 24, 2014. Gyanendra Sharma et al.
• Journal of pediatric urology 2014,10,982-999Multidisciplinary consensus on the classification of
prenatal and postnatal urinary tract dilation (UTD classification system) Hiep T. Nguyen d et al.
• Indian J Nephrol. 2013 Mar-Apr; 23(2): 83–97.Revised guidelines on management of antenatal
hydronephrosis A. Sinha, A. Bagga,et al.
• Journal of pediatric urology VOLUME 15, ISSUE 2, P128-137, APRIL 01, 2019,Diuresis renography in the
evaluation and management of pediatric hydronephrosis: C.E. Bayne et al.
• Fanaraff & Martin’s Neonatal-perinatal medicine 11
th
edition.
• AIIMS NICU protocols 2020
• Pediatrics office journal of the american academy of pediatrics Antenatal Hydronephrosis as a Predictor
of Postnatal Outcome: A Meta-analysis Richard S. Lee et al. Pediatrics August 2006,

44. THANK YOU