Antenatal Hydronephrosis: When to Worry, When to Follow Up

Roberto Gordillo, MD Associate Professor of Pediatrics Division of Nephrology Seattle Children’s Hospital University of Washington Division of Nephrology Congenital anomalies of the kidney and urinary tract (CAKUT)

Division of NephrologyDivision of Nephrology Kostfeld A, Medgen 2018 End-Stage Kidney Disease in Children

Division of NephrologyDivision of Nephrology Antenatal Urinary Tract Dilatation

• Increasing screening with ultrasounds during pregnancy has led to more detection of antenatal hydronephrosis • Most common abnormality in prenatal US • 1%-5% of all pregnancies in the USA • Clinical practices vary regarding recommendation for follow up • Cost and procedures postnatally are a concern

Division of NephrologyDivision of Nephrology Hydronephrosis

• Distention and dilation of the pelvocalyceal system • It is not equivalent to obstruction or reflux • 10-20% of neonates will have a true obstruction

Division of NephrologyDivision of Nephrology Hydronephrosis

Choi YH, Ultrasonography 2016

Division of NephrologyDivision of Nephrology Severity of Hydronephrosis

• No evidence correlating severity and uropathies 1. No uniform definition 2. Different terminologies 3. UT dilatation is a dynamic process 4. Uropathies present in a spectrum of severity

Division of NephrologyDivision of Nephrology Post-natal evaluation

• US at 4 days after birth. • US should not be done before 4 days after birth because dehydration and decreased GFR may lead to false negatives • US is done within 1 or 2 days of birth if bilateral hydronephrosis, PUV or sever hydronephrosis in single kidney

Division of NephrologyDivision of Nephrology Etiology

Young HC. Ultrasonography 2016 Division of NephrologyDivision of Nephrology Transient Hydronephrosis

• Incidence 41-88% • Immature and poorly coordinated peristalsis of the smooth muscle of the renal pelvis

Choi YH, Ultrasonography 2016

Division of Nephrology Ureteropelvic Junction Obstruction

• Functional or anatomic obstruction of urine flow at UPJ • Most common cause of hydronephrosis • Male and left-side predominance

Choi YH, Ultrasonography 2016

Division of NephrologyDivision of Nephrology Vesicoureteral reflux

• Retrograde passage of urine from the bladder to the ureter and calyces

Choi YH, Ultrasonography 2016

Division of NephrologyDivision of Nephrology Duplex Collecting System

• One kidney that is drained by two collecting systems

Division of NephrologyDivision of Nephrology Posterior Urethral Valve

• Most common cause of urethral obstruction in male patients • Bilateral hydronephrosis with thick-walled bladder

Choi YH, Ultrasonography 2016

Division of NephrologyDivision of Nephrology UTD Classification System

Nguyen H et al. J Pediatr UrolDivision2014 of NephrologyDivision of Nephrology Normal Parameters

Nguyen H et al. J Pediatr UrolDivision2014 of NephrologyDivision of Nephrology UTD Risk Stratification

Division of NephrologyDivision of Nephrology UTD P1 (Low risk)

Division of NephrologyDivision of Nephrology UTD P2 (intermediate risk)

Division of NephrologyDivision of Nephrology UTD P3 (high risk)

Division of NephrologyDivision of Nephrology Risk-Based Management

Division of NephrologyDivision of Nephrology Follow up

• For neonates with h/o antenatal hydronephrosis: normal US at birth does not rule out obstruction • US is generally recommended at 4-6 weeks of age • A series of two normal postnatal US are needed to rule out obstruction or VUR • ~98% of mild hydronephrosis will resolve spontaneously • ~90% of moderate hydronephrosis (10-15mm) will resolve by 12- 14 months

Division of NephrologyDivision of Nephrology Moderate and Severe Hydronephrosis Follow up

• Voiding cystourethrogram (VCUG)

• Mag 3 Scan

Division of NephrologyDivision of Nephrology Vesicoamniotic shunt

CHOP.edu

DivisionMorris RKof 2007NephrologyDivision of Nephrology Summary

• Antenatal hydronephrosis does not equate to obstruction or reflux • Mild to moderate will resolve spontaneously • Early detection of CAKUT might improve outcome • Follow up with US is warranted • Prenatal and postnatal consult to Nephrology/Urology is recommended

Division of NephrologyDivision of Nephrology

Division of Nephrology