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I have to pee: fetal bladder outlet obstruction, evaluation

and treatmentJoanne Stone, MD MS

Icahn School of Medicine at Mount Sinai

Fetal hydronephrosis

• Most common birth defect (0.5-5% pregnancies• High sensitivity, low specificity• >50% transient or physiologic

Differential diagnosis

Obstructive

Ureteropelvic junction obstructionUreterovesical junction obstructionMulticystic dysplastic kidneyUreteroceleDuplicated collecting systemPosterior urethral valvesEctopic ureterUrethral atresiaSacrococygeal teratomahydrometrocolpos

Non-Obstructive

Vesicoureteral refluxPhysiologic dilationPrune-belly syndromeRenal cystic diseases

• 1678 infants from 17 centers• Incidence of renal/urinary tract

pathology

• Mild hydronephrosis: 12%

• Moderate hydronephrosis: 45%

• Severe hydronephrosis: 88%

Trimester Mild Moderate Severe

second ≤7 mm 7 to 10 mm >10 mm

third ≤9 mm 9 to 15 mm >15 mm

Classifications

• Renal Pelvic Diameter (RPD)

• Society of Fetal Urology (SFU) criteria

• Urinary Tract dilation (UTD) classification system

Renal Pelvic Diameter• Measures collecting system only

• No consensus on threshold RPD that defines clinically significant fetal hydronephrosis and need for post-natal follow-up

• 4-5mm lowest cut-off

• ≥ 4 – 10mm mild

• > 10mm in 2nd and >15mm in 3rd

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Society of Fetal Urology (SFU)

Dilated renal pelvis only Dilated renal pelvis+ few dilatated calyces

All calcyces dilatedand seen

Grade 3 + parenchymal thinning

Add descriptions: SFU grade 4 UPJ hydronephrosis, SFU grade 4 UVJ hydronephrosis

Urinary tract dilation (UTD) classification system

• Antenatal (A) and Postnatal (P) classification

• Based on US findings, stratified by GA and whether A or P

• Anterior and posterior RPD (APRPD)• Calyceal dilation• Renal parenchymal thickness• Renal parenchymal appearance• Bladder abnormalities

• Normal: APRPD• < 4mm 16 – 27 w• < 7mm at ≥ 28 w

• A1: • normal urinary tract with 4 - < 7mm APRPD

at 16-27 w• or 7 to <10 mm at ≥ 28 w with or w/o

central calyceal dilation

• A2-3: • APRPD ≥ 7mm at 16-27 w

• or ≥10mm at ≥28 weeks, peripheral calyceal dilation, ureteral dilation, renal parenchymal or bladder abnormalities

What class?

16-27 weeksAPRPD 4-7mmCentral calyceal dilation

≥ 28 weeksAPRPD 7-<10 mmCentral calyceal dilation

A1

A2-3

UTD system:Requires more descriptive

terms to communicate

Natural history

• Mild – 88% resolve in fetal/neonatal period• Moderate- severe: 30% persisting in 3rd trimester require postnatal

surgery

Evaluation of fetal hydronephrosis

• Severity and bilaterality increase risk of congenital anomalies of kidney and urinary tract• Repeat US in 3rd trimester – prognosis for intervention postnatally

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Hydroureter

• Vesicoureteral reflux (VUR)• Obstruction distal to

uretopelvic junction (uretocele, megaureter, posterior urethral valves)

Ureterocele

• Cystic dilation of distal intravesical portion of the ureter• Often at orifice draining upper pole of duplicated kidney

Renal parenchyma

• Thinning• < 3mm• Does not

necessarily correlate with poor renal function

• Cortical cysts• Echogenic kidneys

Bladder

• Bladder thickness –obstruction distal to bladder• Keyhole sign• Bladder enlargement:

sagital diameter of GA weeks (mm) + 2 mm• Often PUV• Urethral atresia• Look for ureteroceles

Diagnosis of LUTO

• 1/5,000 – 1/25,000 pregnancies• Markedly distended bladder often with thickened wall• Dilated ureter and calyces – 40-50% LUTO• Cortical cysts, hyperechoic kidneys – end stage• Differential diagnosis• PUV – males• Urethral atresia –females

• r/o persistent cloaca• Caudal regression• Mega-cystis--microcolon-intestinal hyperperistalsis syndrome

• ureterocele

Evaluation of LUTO

• Anatomic survey• Fetal echocardiogram• AF volume assessment• Genetic testing (10% associated with Trisomies 13, 18, 21)• f/u assessments• With oligohydramnios and desire for possible intervention, assess

renal function

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Treatment

• Indications• Male fetus• Second trimester• Bilateral disease• Reasonable fetal urinary studies• Progressive oligohydramnios

• Options• Vesico-amniotic shunting• Valve ablation via cystoscopy• Vesicostomy• Serial amnioinfusion

Evaluation of fetal urine

• 2 consecutive vesicocenteses• 22g spinal needle• Color flow to avoid umbilical

arteries• 1st bladder tap

• Can send for genetic evaluation (CMA)

• +/- electrolyte analysis• 2nd bladder tap

• 24-48 hours later• Na, Chl, Osm, Ca, beta-2

microglobulin

Urinary component Favorable prognosis

Sodium (Na) < 100 mEq/l

Chloride (Cl) < 90 mEq/l

Osmolarity (Osm) < 210 mEq/l

Calcium (Ca) <2 mmol/l

Beta-2 macroglobulin < 2 mg/l

Fetal urine hypotonic until 22 weeks and not necessarily reflective of renal function at birth despite intervention

• Calcium and sodium > 95%ile for GA – best predictors for abnormal post-natal renal function• Due to small study samples and varying thresholds of urinary

markers, fetal urine analysis is still not helpful in predicting postnatal renal outcome.

Proteomic approach: 12 peptides in fetal urine were predictive of developing end-stage renal disease

Fetal serum beta-2 macroglobulin better correlated with postnatal serum creatinine

Klein J, Let al Sci Transl Med.2013;5:198 Luton D, Deet al. Clin Biochem.2013;46(15):1607–10

Vesico-amniotic shunting

• Technique• Seldinger technique• Pigtail shunt ( Rodeck, Rocket, Harrison)

• Complications• Shunt blockage, migration• Preterm labor, urinary ascites, infection, IUD

Trial stopped early due to poor recruitment

Of 12 neonates surviving to 28 days:2/12 showed no renal impairment (shunt)

Analysis based on RX: benefit of shunt on survival at 28 days (RR 3.2, 95% CI 1.06-9.62), 1 year (RR 4.27, 95% CI 1.07-16.96), and 2 years of age (RR 4.27, 95% CI 1.07-16.962/10 who survived to age 2 had no renal impairment

May improve survivalLong term outlook is poor

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2016 retrospective study on 30 male fetuses – survival at 1 and 2 years 57 and 54% and normal renal function in 76 and73% survivors at 1 and 2 years

Fetal cystoscopy for PUVLimited data including systematic review of 4 papers on cystoscopy vs VAS – no improvement in survival in one particular approach

2015 case control of 34 fetuses – cystoscopy improved diagnosis and allowed better selection of fetuses with true PUV for VAS placement

Study of 20 fetuses undergoing cystoscopy and laser ablation: 9 terminated, 11 delivered at mean 37 weeks

8/11 survivors had normal renal function3/11 awaiting transplant

Sananes Net al. PrenatDiagn. 2016;36(4):297–303, Ruano R et alUltrasound ObstetGynecol. 2015;45(4):452–8, Morris RK et al Ultrasound Obstet Gynecol.2011;37(6):629–37Martínez JM et al Fetal Diagn Ther. 2015;37(4):267–7,

• 30% technical failure with fetal cystoscopy• No valid proof of superiority of FC vs VAS• VAS may not improve kidney function and may worsen urologic

function• FC limited by technical factors and lack of reproducibility

Take aways

• Renal pelviceal dilation/hydronephrosis

• Mild – 88% resolve in fetal/neonatal period

• Moderate- severe: 30% persisting in 3rd trimester require postnatal surgery

• UTD classification helpful in communication between subspecialties

• LUTO

• Treatment depends on fetal sex, renal function, oligohydramnios

• Urine studies not that helpful especially < 22 weeks

• Shunts may improve survival but outcome is still poor

• Currently no evidence of superiority of cystoscopy over VAS