Obstructed kidneys –

What to do?Des Sankar

Second Trimester Antenatal Surveillance

Detects a significant fetal anomaly in 1% of pregnancies

20 to 30% are genitourinary in origin

50% manifest as hydronephrosis

Incidence of ANH is 2-9/1000

Hydronephrosis implies obstruction

Better term – an increased Renal Pelvic Dilatation (RPD) as not all cases with

increased RPD are associated with obstruction

If not detected antenatally,

hydronephrosis can result in……

Pyelonephritis

Recurrent loin or abdominal pain

Renal calculi

Hypertension

End-stage renal disease

Aetiology of ANH

Transient/Physiological 50-70%

PelviUreteric Junction Obstruction 10-30%

Vesicoureteral reflux 10-40%

Uterovesical junction obstruction/megaureter 5-15%

Multicystic dysplastic kidney 2-5%

Posterior urethral valves 1-5%

Ureterocoele, ectopic ureter, duplex system Uncommon

Prune belly syndrome, polycystic kidney disease

Cysts

Nguyen et al.2010. The Society for Fetal Urology consensus statement on the evaluation and management of

Antenatal hydronephrosis. J Pediatr Urol 201;6:212-31

Antenatal Hydronephrosis (ANH)

Common 2 approaches of assessment

1. Anterior-posterior renal pelvic diameter

2. Society for Fetal Urology grading

AP Diameter

Second Trimester > 4mm

Third Trimester > 7mm

Based on published work of Lyn S Chitty and Douglas G Altman

94% of fetuses with an AP diameter of >20mm

50% with AP diameter of 10 to 15mm

3% with < 10mm

Required surgery or at least longterm monitoring for a significant urinary tract

lesion

Charts of fetal size:Kidney and renal pelvis measurements. Prenat Diag:2003Nov,23(11)891

Stocks A,et al: Correlation of prenatal renal pelvic anteroposterior diameter with outcome in infancy.

J Urol. Mar 1996;155(3):1050-2

AP Diameter

Second Trimester 7mm or more

Fetal Anomaly Screening Program (NHS)

Third Trimester >10mm

OR

Smaller diameters associated with Calyceal Dilatation

SFU grading Grade 0:- No dilatation

Grade 1:- Renal pelvic dilatation with or without infundibula visible

Grade 2:- RPD with calyces visible

Grade 3:- Renal pelvis and calices dilated

Grade 4:- Grade 3 with parenchymal thinning

Ultrasound appearance of HNa. SFU grade 0 b. SFU grade 1

c. SFU grade 2 d. SFU grade 3

e. SFU grade 4

f. transverse plane with AP

diameter indicated by white cross-

marks

SFU

Second trimester RPD

Mild 4 to <7mm

Moderate 7 to < 10mm

Severe > 10mm

Third Trimester RPD

Mild 7 to < 9mm

Moderate 9 to < 15mm

Severe > 15mm

Correlation with Outcomes

Larger the RPD……………………………..Caused by Obstructive Uropathy

The greater the risk of postnatal surgery

The lower the spontaneous resolution rate

Exception is with vesicoureteric reflux

Views that should be obtained

Spine AnteriorParasagittal for the length

Coronal for symmetry and echogenicity

In addition to the measurements, one should

also document……calyceal dilatation

Normal

…..Parenchymal Thickness/Appearance

1. Thickness

2. Echogenicity

3. Cysts

…..Ureter not usually visible

……..Bladder Normal/Abnormal

1. Should empty every 20 to 30mins

2. Bladder wall thickness

ureterocoele

“keyhole” bladder

………Amniotic fluid volume

Enquire about ruptured membranes

Aetiology of ANH

Transient/Physiological 50-70%

PelviUreteric Junction Obstruction 10-30%

Vesicoureteral reflux 10-40%

Uterovesical junction obstruction/megaureter 5-15%

Multicystic dysplstic kidney 2-5%

Posterior urethral valves 1-5%

Ureterocoele, ectopic ureter, duplex system Uncommon

Prune belly syndrome, polycystic kidney disease

Cysts

Nguyen et al.2010. The Society for Fetal Urology consensus statement on the evaluation and management of

Antenatal hydronephrosis. J Pediatr Urol 201;6:212-31

Embryology – Ureteric Bud gives rise to the ureter, the renal

pelvis, the major and minor calyces and 1 to 3 million

collecting tubules

Collecting

System

Excretory System

Physiological

Maternal overhydration

? Compression of the ureter by distended fetal bladder

70% of fetuses over a 2 hour period, exhibited both normal and abnormal

values (RPD <4mm to <10mm)

Striking findings concerning the variability in the measurement of the fetal renal

collecting system.

PersutteWH;et al UOG 2000;15:186-190

Delayed canalization of the ureter

PUJ Obstruction

PUJ is the most common cause of hydronephrosis in children.

May be the result of incomplete recanalizaton of the proximal ureter, abnormal development of

ureteral musculature, abnormal peristalsis, ureteral valves or polyps.

Causes functional obstruction.

Male: female ratio is 2:1.

Commoner on left side

10% bilateral

Management

Antenatal follow-up scans & Generally deliver at term

Unilateral carries a good outcome

Bilateral hydronephrosis and oligohydramnios increased incidence of structural anomaly (cardiac, neurological and orthopaedic)

Post delivery

Mild unilateral or bilateral

No antibiotics

Renal tract US within 2w of birth

Reuss A, et al 1988

Moderate/severe or mild bilateral with

one other abnormality……………

Antibiotics

US in the first few days of life

Paediatric urology follow-up

VCU and MAG3 scans

Multicystic dysplastic kidney

MCDK

PUJODiscriminatory feature:- echogenic stroma

MCDK

Congenital maldevelopment in which the renal cortex is replaced by

numerous cysts of varying sizes

Usually unilateral and if very large, it can occasionally compress the

contralateral ureter

Bilateral – incompatible with life

Rarely associated with hypertension and malignancy

Needs paediatric follow-up

No antibiotics are required post delivery

Posterior Urethral Valves

Commonest cause of obstructive

megacystis

Abnormal congenital obstructing

membrane located in the posterior

urethra

Mechanical obstruction increases

voiding pressures and may alter

the development of the bladder

and kidneys

Symptoms – mild voiding disability

to severe – renal failure and

pulmonary hypoplasia

VCU :- dilated bladder with trabeculation,

diverticula and bilateral massive reflux

Once hydronephrosis occurs, renal dysplasia and cyst formation occurs.

Antenatal vesico-amniotic shunting does not improve renal function. It

does however, reduce the risk of pulmonary hypoplasia – amniotic fluid is

important for lung development

PUV delivery….

At 37 -38w

Might require ventilator support

In an institution with paediatric surgical expertise- immediate catherization

Survivors of the initial hurdle, will require early surgical intervention –

cystoscopy and ablation of the posterior valves

>30% will require renal transplant

Pregnancy interruption if detected early …… should be an option.

Pelviureteric Reflux

Post delivery VCU

In Summary

Renal Pelvic Dilatation is not uncommon

Once detected, assess the entire renal tract

Document the findings

Discuss findings (with available images) with the paediatric urologist and

paediatrician and formulate a plan of action