radiologic diagnosis of fetal hydronephrosis
TRANSCRIPT
Sabrina Vineberg, HMS IIIGillian Lieberman, MD
Radiologic Diagnosis of Fetal Hydronephrosis:
Associated Abnormalities and Fetal Outcome
Sabrina Vineberg, Harvard Medical School, Year IIIGillian Lieberman, MD
March 2003
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Sabrina Vineberg, HMS IIIGillian Lieberman, MD
Fetal Imaging Modalities• Ultrasound:
– Fast and safe (no ionizing radiation)
– Allows for good visualization of fetal anatomy and live, real-time imaging
– Efficient method to survey for fetal anomalies
• MRI:– Better soft tissue contrast
for characterization of anomalies
– Better than US in patients with oligohydramnios
– Currently no known adverse effects
BIDMC PACS
Levine D. and R. R. Edelman. Abdominal Imaging. 22: 589-596, 1997.
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Sabrina Vineberg, HMS IIIGillian Lieberman, MD
Diagnosis of Fetal Hydronephrosis on Ultrasound
• Index patient:– Mrs. S. is a 34 y.o. G2P1 who presented to
BIDMC at 29+6 weeks GA for a follow-up fetal ultrasound after a routine fetal survey at an outside hospital documented unilateral fetal hydronephrosis.
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Sabrina Vineberg, HMS IIIGillian Lieberman, MD
Mrs. S.’s UltrasoundSpine
Left kidney, sagittal view Right kidney, sagittal view
*
**
*
*
*
** = dilated renal pelvis
Transverse view Sagittal view
R
L
R
L
Calyceal dilatation
US findings: mild hydronephrosis on the right with central dilatation of 8-9 mm and severe hydronephrosis on the left with a large extrarenal pelvis measuring 2.8 cm
All images from BIDMC PACS
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Sabrina Vineberg, HMS IIIGillian Lieberman, MD
Normal Fetal Kidneys
S = spine
Kidneys outlined by arrowheads
• Fetal kidneys are ovoid bilateral paraspinous structures:
- Renal pelvis – “slit-like” lucency within central portion of kidney.
- Medulla – hypoechoic regions surrounding renal sinuses.
- Cortex – thin and difficult to visualize on US.
- Retroperitoneal fat – echogenic density surrounding kidneys.
Gabbe: Obstetrics - Normal and Problem Pregnancies, 4th ed., Copyright © 2002 Churchill Livingstone, Inc.
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Sabrina Vineberg, HMS IIIGillian Lieberman, MD
Renal Development Timeline and Important Structures
• Ureteral bud (week 4) → mesoderm, arises from oupouching of mesonephric/Wolffian ducts, opens into urogenital sinus. Gives rise to ureter, renal pelvis, calyces and collecting system
• Metanephric cap (week 5-6) → mesoderm, interacts with structures of ureteral bud to form functional renal parenchyma
• Cloaca (week 4) → endoderm, divides into urogenital sinus (cranial) and anorectal canal (caudal). Urogenital sinus gives rise to bladder and urethra
• Fetal kidneys begin to function at the start of the 2nd
trimester. By week 16-18 they become the major source of amniotic fluid for the fetus
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Sabrina Vineberg, HMS IIIGillian Lieberman, MD
Renal Development
Week 6 Week 8 Week 10
Migration of the fetal kidneys
Urogenital Sinus
Ureteric bud
Metanephric cap
Embryo 5-6 weeksMesonephric Duct
Sweeney, Lauren J. Basic Concepts in Embryology. A Student's Survival guide. New York: The McGraw-Hill Companies, 1998.
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Sabrina Vineberg, HMS IIIGillian Lieberman, MD
Fetal AnatomyBladder
KidneySpleen
Iliac WingLiver
Lungs
Amniotic fluid
Nyberg, David A., Barry S. Mahony and Dolores H. Pretorius. Diagnostic Ultrasound of Fetal Anomalies: Text and Atlas. Chicago: Year Book Medical Publishers, 1990.
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Sabrina Vineberg, HMS IIIGillian Lieberman, MD
Hydronephrosis• Hydronephrosis (HN) → dilatation of the pelvis
and/or calyces of the kidney• Diagnosis of fetal HN is increasing with increased
use of ultrasound in pregnant women• 1-2% of pregnancies may show evidence of HN,
and it accounts for 50-75% of prenatally diagnosed renal abnormalities.
• Degree of dilatation required for diagnosis of HN varies with gestational age, and is determined using the anteroposterior diameter of the renal pelvis.
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Sabrina Vineberg, HMS IIIGillian Lieberman, MD
Measuring Renal Dilatation•Anteroposterior diameter (APD): Size of the renal pelvis measured in the anterior → posterior direction on a transverse view through the abdomen.
•For a diagnosis of hydronephrosis, APD must be greater than:
- 6mm at < 20 weeks GA
- 8 mm at 20-30 weeks GA
- 10mm at > 30 weeks GAClose-up of a mildly dilated right
fetal kidney on ultrasound(short arrows outlining kidney)
S = Spine
APD
Image from BIDMC PACS
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Sabrina Vineberg, HMS IIIGillian Lieberman, MD
Grades of Fetal Hydronephrosis
Gloor, J.M. Mayo Clinic Proceedings. 70: 145-152, 1995
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Sabrina Vineberg, HMS IIIGillian Lieberman, MD
Natural History of Fetal Hydronephrosis
• Most cases of prenatally diagnosed HN (~90%) will resolve spontaneously before birth or after delivery.
• Of those cases that do not resolve on their own, the majority are amenable to surgical or medical correction after delivery.
• Surgery is best performed within the first year of life to minimize irreversible damage.
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Sabrina Vineberg, HMS IIIGillian Lieberman, MD
Causes of Fetal Hydronephrosis• Physiologic:
– Urine production 4-6x greater before delivery– Increased compliance of fetal ureter– Partial/transient obstructions associated with development
• Pathologic:– Almost always due to obstruction, which can occur anywhere in
the urinary tract– Degree of dilatation depends on the severity and location of
obstruction– Severe or longstanding obstruction of the urinary tract can lead to
permanent renal damage and to systemic problems for the fetus– Non-obstructive causes of HN include vesicoureteric reflux
(VUR), prune belly syndrome and renal cysts.
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Sabrina Vineberg, HMS IIIGillian Lieberman, MD
Radiologic Findings• Can be unilateral or bilateral• Severity of dilatation depends on the level of
obstruction. Common locations include:– Ureteropelvic junction → most common location of obstruction– Vesicoureteral junction → with or without reflux– Vesicouretheral junction → often due to posterior urethral valves
• Renal parenchymal changes• Amount of amniotic fluid:
– With severe obstruction and renal atrophy, the fetus can’t produce or excrete amniotic fluid, leading to oligohydramnios
– Oligohydramnios is a poor prognostic sign for the fetus → risk of pulmonary hypoplasia - lack of amniotic fluid causes compression of fetal lungs which prevents lung development.
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Sabrina Vineberg, HMS IIIGillian Lieberman, MD
Radiologic Findings – US Dilatation of Renal Pelvis and Calyces
• Patient A: Follow-up US for known HN, 27 weeks GA
– US Report: “Worsening bilateral central renal collecting system dilatation, left greater than right, which is out of proportion to caliectasis and suggests UPJ obstruction”.
• Patient B: Routine fetal survey, 22 weeks GA
– US report: “Mild bilateral hydronephrosis. Follow-up is recommended in six weeks and post partum.”
Spine
Patient A - Transverse view
Patient B - Sagittal view
Calyceal dilatation
All images from BIDMC PACS
R. kidney L. kidney
* = dilated renal pelvis
**
**
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Sabrina Vineberg, HMS IIIGillian Lieberman, MD
Radiologic Findings – US Dilatation of Renal Pelvis and Ureters
• Patient C: US with biophysical profile for post-dates at 40 weeks GA
– US report: “Bilateral hydroureteronephrosis. Follow up study of the kidneys is recommended after the baby is born”.
• Patient D: Routine fetal survey, 28 weeks GA
– US Report: “Central renal dilatation of 11 mm on the left and 8 mm on the right, out of proportion to caliceal dilatation along with intermittent visualization of the ureters, which appear mildly dilated. Findings are suggestive of vesicoureteral reflux”.
Patient C - Transverse view Patient C – L. ureter
Patient D - Sagittal view
Ribs
Spine
Dilated ureter
Dilated ureter
*
*Aortic bifurcation
***
Spine
Kidneys
All images from BIDMC PACS* = dilated renal pelvis
Dilated ureter
Bladder
Kidney
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Sabrina Vineberg, HMS IIIGillian Lieberman, MD
Radiologic Findings - MRI
K
A
P
T2W MRI scan at 32 weeks GA showing moderate fetal HN
Fetal Brain
Sagittal MRI showing severe HN in a 33 week old fetus with
obstruction due to posterior urethral valves. US study limited
by severe oligohydramnios.
K= maternal kidney
A = amniotic fluid
P = placenta
Dilated fetal kidneyFetal kidneys
Spine
Fradin, J.M. et al. Urology. 53:825-827, 1999. Miller, O.F. et al. The Journal of Urology. 168:1158-2259, 2002.
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Sabrina Vineberg, HMS IIIGillian Lieberman, MD
Amount of Amniotic FluidNormal amniotic fluid
Normal fetus
Severe oligohydramniosFetus with renal agenesis
All images from BIDMC PACS
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Sabrina Vineberg, HMS IIIGillian Lieberman, MD
Why is prenatal diagnosis important?
• With severe obstruction and oligohydramnios:– Fetus at risk of renal dysplasia and pulmonary
hypoplasia which is often fatal– Prenatal intervention can be lifesaving:
i. Percutaneous fetal shunt catheters – a route for amniotic fluid to leave the urinary tract and return to the amniotic cavity
ii. Surgical exteriorization of fetal urinary tract
• Knowledge of moderate→severe cases of HN antenatally allows for appropriate follow-up and prompt correction after birth
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Sabrina Vineberg, HMS IIIGillian Lieberman, MD
Management of Hydronephrosis In the Fetus and Neonate
Callen, Peter W. Ultrasonography in Obstetrics and Gynecology. 2nd ed. Philadelphia: WB Saunders Co., 1988.
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Sabrina Vineberg, HMS IIIGillian Lieberman, MD
Management of Hydronephrosis in the Neonate
• Prophylactic antibiotics to prevent UTI and pyelonephritis associated with reflux
• Follow-up ultrasound, at least 72 hours after birth
• Other imaging studies include voiding cystourethrogram (VCUG) or DMSA scan
• Prompt surgical correction of obstruction if necessary, to prevent irreversible renal parenchymal damage
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Sabrina Vineberg, HMS IIIGillian Lieberman, MD
Radiologic Work-up of Hydronephrosis in the Neonate
• Radiologic imaging of a newborn diagnosed with hydronephrosis in utero:
– US: Bilateral dilatation of the renal collecting system
– VCUG: Significant reflux bilaterally– DMSA scan: Decreased uptake bilaterally,
L>R
Right kidney Left kidney
Voiding cystourethrogram DMSA scan
Ultrasound
All images from ACR Pediatric Learning File, 1998.
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Sabrina Vineberg, HMS IIIGillian Lieberman, MD
References• American College of Radiology Pediatric Learning File. Version 2.02. CD-ROM. ACRI Software Development, 1998.• Callen, Peter W. Ultrasonography in Obstetrics and Gynecology. 2nd ed. Philadelphia: WB Saunders Co., 1988.• De Bruyn, R. and I. Gordon. Postnatal investigation of fetal renal disease. Prenatal Diagnosis. 21: 984-991, 2001.• Fradin, J.M. et al. Hydronephrosis in pregnancy: simultaneous depiction of fetal and maternal hydronephrosis by magnetic resonance
urography. Urology. 53:825-827, 1999.• Gabbe, Steven G., Jennifer R. Niebyl and Joe Leigh Simpson. Gabbe: Obstetrics - Normal and Problem Pregnancies. 4th ed. New
York: Churchill Livingstone, 2002.• Gloor, J.M. Management of Prenatally Detected Fetal Hydronephrosis. Mayo Clinic Proceedings. 70: 145-152, 1995.• Levine, D. and R.R. Edelman. Fast MRI and its application in obstetrics. Abdominal Imaging. 22: 589-596, 1997.• Miller, O.F. et al. Diagnosis of urethral obstruction with prenatal magnetic resonance imaging. The Journal of Urology. 168:1158-
2259, 2002.• Mouriquand, P.D.E. et al. Pathophysiology, diagnosis and management of prenatal upper tract dilatation. Prenatal Diagnosis. 21:
942-951, 2001.• Nyberg, David A., Barry S. Mahony and Dolores H. Pretorius. Diagnostic Ultrasound of Fetal Anomalies: Text and Atlas. Chicago:
Year Book Medical Publishers, 1990.• Poutamo, J. et al. Diagnosing fetal urinary tract abnormalities: benefits of MRI compared to ultrasonography. Acta Obstetricia et
Gynocologica Scandinavica. 79: 65-71, 2000.• Sairam, S. et al. Natural history of fetal hydronephrosis diagnosed on mid-trimester ultrasound. Ultrasound in Obstetrics and
Gynecology. 17: 191-196, 2001.• Shokeir, A.A. and R.J.M. Nijman. Antenatal hydronephrosis: changing concepts in diagnosis and subsequent management. BJU
International. 85: 987-994, 2000.• Sherer, D.M. Is fetal hydronephrosis overdiagnosed. Ultrasound in Obstetrics and Gynecology. 16: 601-606, 2000.• Sweeney, Lauren J. Basic Concepts in Embryology. A Student's Survival guide. New York: The McGraw-Hill Companies, 1998.
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Sabrina Vineberg, HMS IIIGillian Lieberman, MD
Acknowledgements
• Gillian Lieberman, MD• Pamela Lepkowski• Deborah Levine, MD• Tejas Mehta, MD• Joseph Makris, MD• Dan Saurborn, MD• Larry Barbaras and Cara Lyn D’amour