Antenatal hydronephrosis.

What has changed?

Dr Nick Plant

Consultant Paediatric Nephrologist

Royal Manchester Children’s Hospital

@nephrology_RMCHRMCH 30th June 2017

A good year on Twitter?

A good year on Twitter?

Overview

� The extent of the problem

� Aetiology

� Algorithms

� PUJO

� Summary

The extent of the problem

� Antenatal hydronephrosis (ANH) is defined as

“Dilatation of antero-posterior (AP) diameter of

renal pelvis ≥7mm at 18-20 weeks gestation”

The extent of the problem

� Antenatal hydronephrosis (ANH) is defined as “Dilatation of antero-posterior (AP) diameter of renal pelvis ≥7mm at 18-20 weeks gestation”…

� …or ≥10mm from 32 weeks onwards� The prevalence ranges from 0.6 - 4.5%� Bilateral in 17 – 54%� Male:female = 1:1, 2:1 or 5:1� 50-70% are transient or physiological � It is important to identify infants with significant

illness that require long-term follow up and/or surgery. Parental anxiety.

Aetiology

� 1. Nguyen H.T., Benson C.B., et al, 2014.

Muitldisciplinary consensus on the

classification of prenatal and postnatal

urinary tract dilatation. Journal of pediatric

urology, 10(6), pp.982-998.

Grading

Grading

� Evaluates:

� The dilatation of the renal pelvis(es)

� Distinguish between central (major) &

peripheral (minor) calyceal dilation

� Parenchymal thickness

Grade 0: no dilation (not shown). Grade 1: renal pelvis is only visualized. Grade 2: renal pelvis as well

as a few, but not all, calyces are visualized. Grade 3: virtually all calyces are visualized. Grade 4:

similar to Grade 3, but when compared with the normal contralateral kidney, there is parenchymal

thinning.

Mild – moderate risk factors

•Unilateral hydronephrosis

•Unilateral hydronephrosis ≥ 7 mm but ≤ 10 mm with single kidney

•Unilateral multicystic dysplastic kidney with normal contralateral kidney

•Unilateral renal dysplasia/hypoplasia with normal contralateral kidney

•Bilateral hydronephrosis ≥ 7 mm but ≤ 10 mm

•Single kidney with normal parenchyma and no dilatation

•Non obstructing ureterocele

•Other kidney abnormality (e.g. echogenic kidney, duplex system,

horseshoe kidney) with normal liquor volume

Postnatal management:

mild - moderate risk

•Antibiotic prophylaxis is not recommended in mild to moderate risk

features, except for those with family history of vesicoureteric reflux

(VUR). If so, commence trimethoprim 2mg/kg PO nocte

•In those requiring follow up scans, it is recommended that the first

post-natal USS be delayed for at least 48 h after birth (because of

reduced urine output in the first 48 hours), but most follow up scans

can be organised for between1-4 weeks

•All newborns with history of antenatal hydronephrosis and

resolution prenatally, do not need further scans postnatally and can

be discharged home safely

Severe risk factors

• Bilateral hydronephrosis ≥ 10 mm• Suspected bladder outlet obstruction (PUV/urethral stenosis or stricture)• Unilateral hydronephrosis ≥ 10 mm in fetus with a single kidney• Renal parenchymal abnormalities bilaterally

- Polycystic kidneys - Congenital nephrotic syndrome- Echogenic kidneys associated with oligohydramnios

Postnatal management:

Severe risk factors

•Commence babies on trimethoprim 2mg/kg PO nocte as

prophylaxis. (NB this indication is unlicensed in children under 6

weeks.)

•In neonates with bilateral hydronephrosis >10 mm, presence of

oligohydramnios or suspicion of posterior urethral valves, post-

natal US should be performed within 3 days birth.

•Micturating cystourethrogram (MCUG) must be performed in

patients with bilateral hydronephrosis >10 mm or bilateral

ureteric dilatation.

•In the absence of bladder outlet obstruction, MCUG can be

performed at 4-6 weeks of age.

•Infants with lower tract obstruction should be immediately

referred to urology for appropriate intervention.

Antenatal Scanning

18-20 week scan

Hydronephrosis ≥ 7mm

Bilateral hydronephrosis ≥

10mm or associated with a single kidney.

Follow bilateral ANH protocol

Repeat scan at 32 weeks

Bilateral ≥ 10mm.Follow bilateral ANH

protocol

<10mm and unilateral.Discharge with no

postnatal investigation

≥10mm and unilateral.Follow unilateral ANH

protocol

Any evidence of ureteric dilatation.

Follow bilateral ANH protocol

Repeat scan at 32 weeks to ensure not bilateral or worsening

Postnatal scanning:

Unilateral hydronephrosis

Postnatal scanning:Bilateral hydronephrosis

Notes

These are high risk groups and bladder outlet obstruction

should be excluded

*There is a recognised (1-2%) risk of introducing urinary

infection at the time of a MCUG. It is recommended that

prophylatic antibiotic therapy is increased to therapeutic

doses for a 48 hour period around the procedure.

neonate: initially 3mg/kg as a single dose then 2mg/kg BD

for 48 hours

child 1month to 12 yrs: 4mg/kg BD for 48 hours

PUJO

� AP >20mm ‘may well’ be associated

with deterioration in renal function

� >30mm = 60% chance of deterioration

� Pelvis can enlarge significantly before

function falls

� The greater the calyceal dilatation, the

greater the risk of deterioration

PUJO

� Consider pyeloplasty if:

� Progressive pelvic dilatation

� Symptoms

� Reduced function on MAG3

� TPD >30mm

Summary

� What’s changed?

� Minor changes to AP diameter limits

� Therefore, fewer investigations

� Earlier discharge from follow up

� Less reliance on MCUGs

� Less prophylactic antibiotics required

A new use for sildenafil?

Finally… Spanish NF1