Postnatal management of antenatal hydronephrosis

1. DR/ MOHAMED ASHRAF MOSTAFA
MS.FRCS

2. OUTLINE
 Introduction
 Definition
 Grading
 Etiology
 Natural history
 Postnatal evaluation
 Imaging
 Management

3. INTRODUCTION
 Fetal hydronephrosis (dilatation of
the renal collecting system) is the
most common abnormality found
on prenatal ultrasound.
 1-5 % of all pregnancy
 Male : female 2:1
 Bilateral in 20-40 %
 The goal of postnatal management
is to identify those with significant
congenital anomalies of the kidney
and urinary tract while avoiding
unnecessary testing in patients
with physiologic or clinically
insignificant hydronephrosis.

4. DEFINITION OF ANTENATAL
HYDRONEPHROSIS(ANH)
 Anteroposterior diameter (APD) of the renal pelvis in the
transverse plane is the most studied parameter for
assessing ANH in utero
 Threshold APD value that separates normal from
abnormal does not exist
 No consensus on the optimal APD threshold for need of
postnatal follow up
 Factors affecting APD:
Gestational age
Hydration status of the mother
Degree of bladder distention

5. Appearance of renal pelvis,
calyces, and renal parenchyma

6. GRADING ANH BY APD
ANH grade APD second
trimester, mm
APD third
trimester, mm
Mild
≤ 7 ≤ 9
Moderate
7–10 9–15
Severe
> 10 > 15
APD greater than 15 mm represents severe or significant
hydronephrosis
A value of 4-5 mm is an appropriate threshold for considering the APD to
be abnormal.

7. ETIOLOGY OF ANH
Etiology
Transient hydronephrosis
UPJ obstruction
VUR
UVJ obstruction /
megaureter
MCDK
PUV/urethral atresia
Ureterocele/ectopic
ureter/duplex system
Others: prune belly
syndrome, cystic kidney
disease,
congenital ureteric
strictures,
megalourethra
Incidence
41%88%
10%30%
10%20%
5%10%
4%6%
1%2%
5%7%
Uncommon

8. Natural history of ANH
 The vast majority of the cases of
hydronephrosis diagnosed during the
second trimester have been noted to
resolve during follow-up imaging in the
third trimester.
- Majority of SFU G1-2 resolve by 18months
- If increasing hydronephrosis occurs , it
does so early in life and often during the
first year.
- Multivariate analysis showed larger APD
and SFU grade 4 to be associated with a
lower likehood of resolution. Michelle et al J
Ped Urol 2011
Surgery
25%
Persistence
23%
Resolution
52%

9. POSTNATAL EVALUATION
PHYSICAL EXAMINATION
 Abdominal mass :enlarged kidney due to obstructive
uropathy or multicystic dysplastic kidney (MCDK).
 A palpable bladder in a male infant, especially after
voiding, may suggest posterior urethral valves.
 A male infant with prune belly syndrome will have
deficient abdominal wall musculature and undescended
testes.

10. POSTNATAL IMAGING OF ANH
 ULTRASOUND
 VCUG
 RADIOISOTOPE STUDIES
 MRU
 IVU

11. POSTNATAL IMAGING OF ANH
ULTRASOUND
 The first postnatal scan must be delayed for a week to
avoid the false-negative results that may be produced by
US within the first 24-48 h when the baby is relatively
oliguric.
 A second scan at 6 weeks is necessary because initial
scans may be normal and subsequent scans may show
postnatal hydronephrosis.
 APD
 Calyceal / ureteral dilation
 Corticomedullary differentiation
 Thinned cortex
 Cortical cysts
 Ureterocele

12. POSTNATAL IMAGING OF ANH
VCUG
○ Vesicoureteral reflux(VUR)
○ Posterior urethral valves(PUV)
○ Ureterocele
 Antibiotics (Amoxicillin 10mg/kg/d or cephalexin
5mg/kg/d) until VCUG done
 Controversy exists around whether children with SFU 0–
2 on postnatal US should get a VCUG.

13. POSTNATAL IMAGING OF ANH
DIURETIC RENOGRAPHY
 RPD is > 10mm even in the presence of VUR
 SFU G3 & G4
 Timing and selection
4–6 weeks of age
 Tc MAG3 is more accurate assessment of both
function and drainage than TcDTPA.
 Clearance of half of the isotope (t ½) within 10-
15min ------------------- no obstruction.
 T1/2 > 20 min ------------ significant obstruction,
while T1/2 15-20 min. is intermediate.

14. POSTNATAL IMAGING OF ANH
DIURETIC RENOGRAPHY
Type 1: normal uptake
with prompt washout
Type 2: a rising uptake
curve with no response to
diuretics, which suggests
obstruction
Type 3: an initially rising
curve that falls rapidly in
response to diuretics,
which suggests non
obstructive dilatation

15. SURGICAL INTERVENTION
 Recommendation for surgical intervention
- Obstructive wash-out curve (T ½ exceeds 20 min.)
with Differential function < 40%
- Progressive decrease in differential function on
sequential nuclear renogram
 Exception to split renal function – severe bilateral
hydronephrosis or obstruction, as the absence of a
normal contralateral kidney with which to compare the
hydronephrotic kidney
 Renal unit that demonstrates the least function should
be repaired first.

16. POSTNATAL IMAGING OF ANH
MRU
Gadolinium-enhanced MRU
 Advantages :
- Superior anatomical and functional information even if
poor function or bilateral disease, no radiation
- Contrast non toxic
 Disadvantages :
- Expensive
- Complexity of the software protocol needed to process
the MRI information
- Requires sedation and monitoring
 For solitary kidneys or bilateral renal involvement,
MRU is superior than DR as individual kidney
function (GFR) may be assessed.

17. POSTNATAL IMAGING OF ANH
IVU
 At 6 weeks
 Advantages : good anatomy if function is good
 Disadvantages : inaccurate if poor function, nephrotoxic
contrast, radiation exposure.
 DR and MRU may not be available and in such cases
intravenous urogram may be the only test used.

18. TRANSIENT HYDRONEPHROSIS
 41 – 88%
 Most children with a pelvic
dilation <6 mm diagnosed
during the 2nd trimester or
<8 mm diagnosed during
the 3rd trimester have
transient hydronephrosis
[Mallik et al Pediat Nephrol 2008].
 Insufficient maturation of
the UPJ or the VUJ
 Fetal ureteric fold
 VUR
Antenatal postnatal

19. UPJ OBSTRUCTION
 Antenately: hydronephrosis with
no ureteric dilatation , normal
bladder and amniotic fluid volume
 10-30%
 Likehood of UPJ obstruction is
more with antenatal APD > 15mm
(Rickood et al BJU 1991)
 Only 19-25% of children with
prenatally diagnosed UPJ
obstruction require surgical
intervention .Diagnosis :1- Diuretic
renography
2- Differential renal
function
 Management : Pyeloplasty if renal
function depressed to < 40% of the
total

20. VUR
 10-20%
 Degree of dilatation does not correlate with VUR
 A normal postnatal US does not exclude reflux
 Antibiotic prophylaxis
 Up to 60% of refluxing units resolve within 2 yrs
including grade IV and V reflux .Most patients with VUR
and low-grade hydronephrosis can be followed without
surgical intervention

21. VUJ OBSTRUCTION / MEGAURETER
 5-10%.
 Megaureter : suspected when dilated ureter >7mm with no
reflux
 Renography is used to differentiate obstructed from non
obstructed megaureter
 The majority will spontaneously resolve during postnatal
follow up - Conservative with similar protocol like UPJ
obstruction
- Surgical excision , tapering of the distal end and
reimplantation --- high complication rate in neonates
- Open insertion of a JJ stent as a temporizing procedure
reported with excellent results

22. MCDK
 4-6 %
 Renal parenchyma is completely replaced
by non communicating cysts of variable
sizes and no discernible renal cortex
 Not hereditary unlike PCKD
 Occasionally confused with UPJ
obstruction
 Diagnosis confirmed with US and DMSA
 Nephrectomy for symptomatic masses of
if infection occurs.
 Management of asymptomatic cases is
very controversial as the incidence of
short term complications is very low and
the MCDK resolves in a number of
patients by the age of 5 years

23. PUV
 1: 8000 newborn
 1) Prenatal hydronephrosis (often
bilateral)
 2) Dilated, thick-walled bladder
that fails to empty
 3) Dilated posterior urethra; and
 4) Decreased amniotic fluid
suggests the presence of lower
urinary tract obstruction
 Elevated fetal urinary Na, Cl & B
microglobulin are antenatal
predictors of poor outcome

24. PUV
- Postnataly: catheterization ----in all
suspected cases
US & VCUG to be done within 48 hrs
- Definite management : PUV ablation
1/3 of patients with PUV eventually develop
renal insufficiency
- Prognosis is worse if the diagnosis is
suspected antenately with severe obstruction,
hydroureteronephrosis and oligohydramnios

25. PUV
ANTINATAL INTERVENTION
Vesicoamniotic shunting
Aim :Decompression will restore amniotic
fluid---> prevent development of fetal
pulmonary hypoplasia .
Intervention is only warranted if the
ultrasound findings and fetal urinary
markers suggest salvageable renal
function
Complications : Shunt blockage or
migration, preterm labor, urinary ascitis,
chorioamnionitis, intrauterine death.
Outcome: Perinatal survival 47%
Post renal insufficiency 87.5%
Intrauterine fulguration of PUV has
been limited to very few centers at this
time

26. URETEROCELE
 Cystic dilatation of
the intravesical ureter
 1:5000
Commonly associated with
duplicated systems
 10-20 % bilateral
 Associated with ectopic
insertion of the ureter in 75 % of cases.
 Postnataly diagnosed by US
 VCUG is used to show whether reflux
is into a lower pole or ectopic ureter
 MAG3 is needed to assess the function
 Treatment :
Initially Endoscopic puncture
Definitive upper pole heminephro-
ureterectomy

27. SUMMARY
 All ANH should be investigated with a post-natal US.
 Antenatal hydronephrosis does not necessary imply
obstruction, nor give any indication of the function of an
affected kidney.
 The role of prophylactic antibiotics initiated at birth is
controversial.
 The need to further investigate mild postnatal
hydronephrosis (SFU 0–2) with a VCUG is controversial,
and depends on the physician’s attitude toward
diagnosing asymptomatic VUR.

28. SUMMARY
 Persistent moderate or severe hydronephrosis (SFU3–4)
should be investigated with a VCUG, followed by diuretic
renography if the hydronephrosis cannot be explained by VUR.
 Most diagnoses made based on a finding of prenatal
hydronephrosis can be handled conservatively.
 Indications for surgical intervention include reduced
differential function (<40%), greater than 5% decrease in
baseline differential function, progressive increase in
hydronephrosis, febrile infection or poor parental
compliance
 Prenatal intervention for hydronephrosis is indicated only
in very select instances and in specialized centers . Even when
well selected, intervention is highly controversial.

29. THANK YOU