Prenatal Diagnosis: interpreting fetal urological pathology and determining post natal follow up

Dr. Castellan Miguel

Nicklaus Children Hospital, Miami, Fl., USA

Joe DiMaggio Children’s Hospital, Hollywood, Fl.

Jackson Memorial Hospital,

University of Miami,

Miami, Fl., USA

Prenatal US: Urinary Tract Anomalies

• Urologic abnormalities: in up to 1.5% of all pregnancies

• At least 50% represent some form of hydronephrosis

• Prenatal US has completely changed the face of pediatric urology/nephrology practice

Blyth B, et al. J. Urol 1993; 149:693. Robyr R., et al. US Obstet Gynecol 2005; 25:478

Prenatal Hydronephrosis

• In most cases, fetal renal pelvic dilation is a transient physiologic state

• Excessive concern may lead to unnecessary testing of the newborn infant and anxiety for parents and health care providers

Prenatal Hydronephrosis

• However, congenital anomalies of the kidney and urinary tract (CAKUT) can present with fetal hydronephrosis

• Goal: to detect cases that may affect the health and require antenatal and postnatal evaluation and management

Prenatal US: Diagnosis

• How do we deal with the large number of prenatally detected urinary tract abnormalities?

• How do we selectively evaluate them perinatally?

• How do we avoid over-testing, without under-testing those who may benefit?

Renal pelvic diameter (RPD): method to define and grade fetal hydronephrosis (maximum AP diameter of the renal pelvis)

AHN by APD for Prenatal Evaluation, Nguyen HT . J. Pediatr. Urol.2010

Classification of Prenatal Hydronephrosis

Second Trimester APD (mm)

Third Trimester APD(mm)

Mild 4-7 7-9

Moderate 7-10 9-15

Severe >10 >15

Prenatal US: Diagnosis

Grading Prenatal Hydronephrosis

SFU

SFU Grade Patterns of renal

sinus splitting US Appearance Grade

APD at >20 weeks

gestation / calyceal

dilation(13)

SFU O No splitting ) n/a

SFU 1 Urine in pelvis barely

splits sinus 1

1 cm

Normal calyces

SFU 2

Urine fills intrarenal

pelvis or Urine fills

extrarenal pelvis and

major calyces dilated

2 1 to 1.5 cm

Calyces are normal

SFU 3

SFU Gr2 + minor

calyces uniformly

dilated and

parenchyma

preserved

3 >1.5 cm

Slight caliectasis

SFU 4

SFU Gr 3 + parenchyma thinning

4 >1.5cm

Moderate caliectasis

5

>1.5cm with severe

caliectasis and

thinning of the renal

cortex <2mm thick

Fernbach SK, et al. Ultrasound

grading of hydronephrosis used by

the SFU. Pediatr Radiol 1993;

23:478.

Prenatal Hydronephrosis: Causes

Prenatal Hydronephrosis

• UPJO increased in frequency with the severity of hydronephrosis

• In contrast, VUR was not associated with the severity of fetal hydronephrosis

• However, moderate to severe reflux (grades III through V) appears to be associated with a greater degree of renal pelvic dilation (RPD >10 mm) and ureter, both in utero and postnatally

Dias CS, et al. J Urol 2009; 182:2440

Risk for CAKUT and postnatal surgical intervention with increasing severity of fetal hydronephrosis • Meta-analysis of 1678 infants from 17 studies:

•Mild hydronephrosis (≤7 mm in the second trimester and/or ≤9 mm in the third trimester): 12 percent

•Moderate hydronephrosis (7 to 10 mm in the second trimester and/or 9 to 15 mm in the third trimester): 45 percent

•Severe hydronephrosis (>10 mm in the second trimester and/or >15 mm in the third trimester): 88 percent

Lee RS, et al. Pediatrics 2006; 118:586

Postnatal longitudinal evaluation of children with prenatal hydronephrosis • 1034 charts of fetuses with PNH

• At last follow-up (mean age 20.6 months), hydronephrosis persisted in children with:

• Mild: 10%

• Moderate: 24%

• Severe: 63%

Barbosa JA, et al. Prenat Diagn 2012; 32:1242

Other Prenatal US findings

• Ureteral dilation: can be consistent with VUR or obstructive uropathy distal to the ureteropelvic junction (eg, ureterocele, megaureter, or PUV)

• Renal parenchyma − Thinning of the parenchyma, cortical cysts and/or increase echogenicity may indicate injury, impaired cortex or abnormal renal parenchymal development (dysplasia)

• Bladder − increased thickness, trabeculation and enlargement of the bladder wall are consistent with obstructive uropathy distal to the bladder (eg, PUV)

Other Prenatal US findings

• Urinoma: extravasated urine encapsulated in the perirenal fascia (can be secondary to urinary obstruction)

• Urinary ascites: secondary to spontaneous/iatrogenic rupture of the bladder and renal calices due to obstruction

• Amniotic fluid volume − Oligohydramnios is consistent with a decreased production of fetal urine (severe renal disease)

Amniotic fluid (AF)

• Fetal urine becomes significant at the start of the second trimester

• By 20 weeks gestation, fetal urine accounts for > than 90 % of the AF vol.

• Oligohydramnios at or beyond 20 week of gestation is used as predictor of abnormal renal function and CAKUT

AU Vanderheyden T, et al. Semin Neonatol. 2003;8(4):279.

Can quantity of amniotic fluid reliably predict postnatal renal function in boys with PUV? • 51 fetuses born with PUV / Nadir creatinine during 1 year of life

• 12 with prenatal oligohydramnios (PO)

• Normal creatinine: 1 had PO (8.33%)

• Creatinine between 35 and 75 μmol/L: 4 had PO (33.33%)

• Creatinine >75 μmol/L, 7 had PO (58.33%)

Luke Harper, Prenatal Diag. vol. 37, 9, 2017, 931-934

Differential Diagnosis of Fetal Hydronephrosis

• Duplication

Upper pole

Lower pole

• Dilated ureter

Dilated,

thickened

bladder

Normal bladder

wall

• Isolated Hydro

Mild, moderate

or severe

Unilateral/Bilat

Ureterocele: Prenatal detection

• Duplex system with upper pole hydronephrosis

• Hydroureter

• Intravesical cystic structure

Ureteroceles can cause bladder outlet obstruction if closely located to the urethra

Bilateral hydroureteronephrosis with thick walled bladder and dilated posterior urethra (keyhole sign) PUV

Guidelines – sort of…

J Pediatr Urol 2014; 10:982.

An attempt to permit a more consistent communication about prenatal hydronephrosis

UTD Grading: Prenatal

Copyrights apply

Grading Postnatal Postnatal

Management

Copyrights apply

Copyrights apply

UTD Grading: Prenatal

Copyrights apply

Postnatal Management

Copyrights apply

Postnatal

Nguyen HT, J Pediatr Urol 2014; 10:982 Postnatal Management

Postnatal evaluation essential

• Ectopic ureter and ureterocele

• Moderate to severe bilateral hydronephrosis in a boy Posterior urethral valves

• Severe unilateral hydronephrosis

• Hydro-ureteronephrosis

Serial MAG-3 scans for UPJO

“Function”: 39% to 32% Washout time (t ½): 11.5 min to 26 min

Observation of infants with SFU 3-4 hydronephrosis

Ross, et al., 2011, J Ped Urol 7:266-71

• 115 pts (125 kidneys) / Overall operative rate of 38%

• Delayed surgery in 21 (21%) at mean of 500 days, 3 showed < DRF

• Cost of multiple studies / Limited F/U in some patients

UPJO: Postnatal Management Severe

MAG-3

DU>45% DU

35-45% DU<35%

Surgery US in 3 mos then 12 mos

US - 3 mos MAG3 - 6 mos

US Stable or Worse

at 12 months

MAG3 with DF

Initial Evaluation of prenatally detected hydronephrosis

US

Antibiotics

VCUG

MAG-3

?

From Swords and Peters, Arch Dis Child Fetal Neonatal Ed 2015; 100:F460-64

The Spectrum of Hydronephrosis

No worries

Follow-up

Fix it

Correlation of degree of hydronephrosis with postnatal outcomes – meta-analysis

0

10

20

30

40

50

60

Perc

en

t P

ostn

ata

l ab

no

rmali

ties

Degree of Hydronephrosis

UPJ

VUR

from Lee et al., Pediatrics 2006, 118(2):586

AUA Guidelines – 2010: Screening for VUR in children with prenatally detected hydronephrosis

• Incidence of VUR is 16%

• No significant difference by hydronephrosis severity

• No significant difference by sex

• 2/3 will have Grade III and greater

• 50% of those with Grade IV-V will have renal cortical

abnormalities

Is this Reflux Clinically Important?

• Ismaili, et al. (2002): 264 infants with prenatal hydro

• Had 2 neonatal US images

• If both normal (74), VCUG abnormal in 5 (6.7%)

• Can select low risk population with post-natal imaging

Not screening for Reflux

• If a VCUG is not to be obtained, the family should be made aware of the clinical signs and symptoms of UTI

• A follow-up US is useful to assess renal growth and ensure the child has been well

• The chance of missing significant reflux is small (postnatal SFU 1-2)

Thanks…

Miguel Castellan, MD

Nicklaus Miami Children's Hospital, Joe Di Maggio Children's Hospital

Jackson Memorial Hospital, University of Miami,

Miami, Fl., USA