This document provides guidelines for evaluating and managing various renal tract abnormalities in neonates, including hydronephrosis, multicystic kidneys, and bladder outflow obstruction. For unilateral hydronephrosis, the guidelines recommend ultrasounds at 1 week and 2-3 months to measure renal pelvis diameter and assess need for further investigation. Bilateral or severe cases may require a MAG3 scan and MCUG. Multicystic kidneys smaller than 6cm often involute with observation, while larger ones may require nephrectomy. Bladder outflow obstruction indicates urgent referral for possible endoscopic treatment to decompress the bladder.

1. Approach to Renal Tract Abnormalities
In Neonates
Dr. Tarek Kotb
MBBCH CAIRO UNIVERSITY
MRCPCH UK
NICU –MCH- Buraydah Qassim

2. ANTENATALLY DIAGNOSED RENAL TRACT
ABNORMALITIES
Urine production is important antenatally for production of
amniotic fluid and the normal development of the urinary
and pulmonary systems.
Abnormalities of the urinary tract are among the most
common detected antenatally and account for a significant
(4%) part of perinatal mortality.
More common in males (60%) than females.

3. HYDRONEPHROSIS
Antenatal detection of hydronephrosis of
any degree should be investigated
postnatally

4. Unilateral hydronephrosis
Should be scanned at 1 week, then again at 2-3
months .
Following the first day check the parents should be
given appointments for both of these scans, and a
clinic appointment following the second. They should
be asked to come to SCBU immediately following the
first, for discussion of the result, which the radiologist
will write down and give to them.

5. Unilateral hydronephrosis
information needed in scan at 1 week
• AP diameter of the renal pelvis
• Presence or absence of dilated calyces
• Length of the kidneys
• Whether dilated ureters are seen
• Bladder wall thickness (if bladder distended)
• Cortical thickness
• Confirmation of the diagnosis
or detection of other structural anomalies.

6. During follow-up we may classify hydronephrosis
based on 3 criteria
1.The largest AP diameter of the pelvis antenatally or
neonatally.
2. Its function based on MAG3 (done at GOS)
3. The presence or absence of reflux into the renal pelvis
based on MCUG

7. (1).The largest AP diameter of the pelvis
antenatally or neonatally
ReferMAG 3
At 2 months
TrimethoprimdischargeAP DIAMETER
♣< 10 mm AFTER 2
MONTHS SCAN
♣10-15 mm
Normal calyces
♣♣10-15 mm
Dilated calyces
♣♣15-19 mm
♣♣♣> 20 mm

8. MCUG should be performed in any case
where:
• There is ureteric dilatation
• The bladder wall is thicker than 5mm
• US suggests renal scarring
• It appears that there may be a ureterocoele
or duplex system
• UTI occurs
• There is bilateral hydronephrosis (both > 15 mm).

9. If MAG3 or MCUG are not indicated, follow up
should be with USS at 6 months (and at one year,
if required).
Infants may be discharged once the AP diameter
is <10mm.
If follow-up is required beyond one year, this is
best provided by general paediatricians

10. (2). Its function based on MAG3
Poor function = < 20% )
Moderate = 20-39% ) of total renal
function
Good = >= 40% )
If function is <44%, the baby should be
referred to consultant pediatric surgeon,
otherwise USS should be repeated at six
months and again with repeat Mag3 at 1yr.

11. (3). The presence or absence of
reflux into the renal pelvis based
on MCUG
If an initial MCUG shows
significant reflux, the presence of
scarring should be investigated
with DMSA at 4 months, and
antibiotics continued.
Babies should then be referred to
consultant pediatric surgeon for
follow up at 1½ yrs (50% have
resolved by 2yrs).

12. Bilateral Hydronephrosis (>15 mm)
1. USS at 2-3 days, Mag-3 at 3/12.
2. Start Trimethoprim.
3. MCUG.
4. Urgent referral to consultant pediatric surgery.
NB USS at < 2 days can be misleading due to low
urine output.

13. MULTICYSTIC KIDNEYS
These are non-functional and
usually associated with an atretic
ureter and often with contra lateral
obstruction.
M>F R>L
65% are impalpable in the first three
months of life.
About 30% of multicystic kidneys
are initially incorrectly diagnosed as
hydronephrosis.

14. •The size of the kidney on USS is important
prognostically as 90% of those >6cm long at
any time tend to increase in size, while those
remaining <6cm tend to involute.
•There is no risk of UTI in an isolated MCDK as
there is no blood supply to the dysplastic
tissue and the cysts constitute a closed
system, however, 10-15% of MCDK have grade
2 vesico-ureteric reflux in the contra-lateral
kidney, and

15. Postnatal investigation of multicystic
kidneys
< 6cm>6 cmUSS
USS at 2 monthsreferAt 1 week
USS at 1 yearreferAt 2 months
Discharge with
yearly BP
referAt 1 year

16. Indications for MCUG and Prophylactic
Trimethoprim
1. Anomaly in contra-lateral kidney pre or
postnatally
2. Abnormal bladder
3. Dilated ureters(s)
4. UTI

17. Indications for Nephrectomy
1. Mass causing respiratory embarrassment or
feeding problems
2. Ipsilateral anomaly (usually ureterocoele)
3. Size > 6cm at 1½ yrs

18. BLADDER OUTFLOW
OBSTRUCTION (PUV)
These males are often born
preterm 30-36wks.
Present with:
1. Bilateral/unilateral
hydronephrosis
2. ± dilated ureter(s)
3. Distended bladder
4. Oligo-hydramnios

19. Management
• Urgent referral especially if distended bladder.
• Do not MCUG before referral as this makes endoscopic
diagnosis and treatment difficult.
• If bladder decompression is necessary before transfer,
this should be via a suprapubic catheter.
• Vesico-amniotic shunting in-utero is still controversial.
Babies with already impaired renal function as suggested
by oligo-hydramnios and abnormal U&E are unlikely to
benefit.

21. THANKS