prenatal diagnosis: interpreting fetal urological...
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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