CAKUT

(Congenital Anomalies of the

Kidneys and Urinary Tract)

and Antenatal Ultrasound

Diagnosis

Dr. Durr-e-SabihMBBS. MSc. FRCP. FANMB

Director MINAR- Multan

Chair, Committee for the Asian Nuclear Medicine Board

Occurrence

o 23-30% of all anomalies detected antenatally on

ultrasound1

o CACUT 3-6/1000 live births

o Syndromic or non syndromic

o Non-syndromic might have a single-gene defect

basis2

1 Queisser-Luft A, Stolz G, Wiesel A, et al. Malformations in newborn: results based on 30,940 infants and fetuses from

the Mainz congenital birth defect monitoring system (1990-1998). Arch Gynecol Obstet 2002; 266:163.

2Ihor V. Yosypiv. Congenital Anomalies of the Kidney and Urinary Tract: A Genetic Disorder? International Journal of

Nephrology Volume 2012, Article ID 909083, doi:10.1155/2012/909083

Significance

Accounts for ~60% CKD (Chronic Kidney Disease),

~30-50% ESRD (End Stage Renal Disease) ~70% of

Childhood hypertension

Seikaly MG, Ho PL, Emmett L, et al. Chronic renal insufficiency in children: the 2001 Annual Report of the NAPRTCS.

Pediatr Nephrol 2003; 18:796.Sanna-Cherchi S, Ravani P, Corbani V, et al. Renal outcome in patients with congenital

anomalies of the kidney and urinary tract. Kidney Int 2009; 76:528.

Embryology of the kidneys

o Pronephros

• Rudimentary, begins day 20 ends day 28, degeneration

of pronephros is required for normal kidney

development

o Mesonphros

• Begins day 26 and develops 20 paired tubules that

produce a small amount of urine, fuses with cloaca to

form bladder, renal pelvis and some tubules

o Metanephros

• Begins 5-6weeks and begins urine production at 9

weeks

• Initially at level of sacral somites and then ascends to

its final position

© http://imindmaps.blogspot.com/2014/01/kidney-embryology.html

CAKUTo Malformation of renal parenchyma

• Agenesis, dysplasia, tubular dysgenesis, cystic

dysplasia, ARPKD and ADPKD

o Abnormalities of migration and fusion

• Pelvic kidneys, horseshoe kidneys, crossed

ectopias,

o Abnormalities in developing the urinary

collecting system

• Primary PUJ obstruction, megaureter, ectopic

ureter, bladder exstrophy, posterior urethral

valves

CAKUTo Malformation of renal parenchyma

• Agenesis, dysplasia, tubular dysgenesis, cystic

dysplasia, ARPKD and ADPKD

o Abnormalities of migration and fusion

• Pelvic kidneys, horseshoe kidneys, crossed

ectopias,

o Abnormalities in developing the urinary

collecting system

• Primary PUJ obstruction, megaureter, ectopic

ureter, bladder exstrophy, posterior urethral

valves

What is the sensitivity

o 82-89% of anomalies can be picked up by

ultrasound (709,030 births)

Wiesel A, Queisser Luft, Clementi M. Prenatal Detection of Congenital Renal Malformations by

Fetal Ultrasonographic Examination: An Analysis of 709,030 Births in 12 European Countries.

Eur J Med Genet. Volume 48. April–June 2005, Pages 131–144

Ultrasound sensitivity

Wiesel A, Queisser-Luft A, Clementi M, et al. Prenatal detection of congenital renal malformations by

fetal ultrasonographic examination: an analysis of 709,030 births in 12 European countries.

Eur J Med Genet 2005; 48:131.

Type of malformation Antenatal pick up

sensitivity

Unilateral multicystic dysplastic kidney 97

Supernumerary kidney 95

Bilateral renal agenesis/dysgenesis 91

Polycystic kidney disease 87

Hydronephrosis 84

Solitary cyst 76

Posterior urethral valves 70

Unilateral renal agenesis 62

Ectopic kidney 56

Bladder exstrophy 53

Total 82

How soon can you see the

kidneys and bladder

o ~13 Weeks, 99% using TAUS/TVS

14 W fetus

What can you see

o Structure

• Renal

• Ureters (if dilated)

• Bladder

o Function

• Amniotic fluid reflects renal and placental

function

• > 16 weeks urine becomes the main source of

amniotic fluid

Structure

o Kidney• Presence

• Number

• Position

• Appearance

o Collection system• Dilatation

• Level of obstruction

• Single or both

o Bladder• Presence

• Appearance and size

Trivia

o In the fetus at 36 weeks’ gestation there is

an adult complement of nephrons- approx.

one million

o All further growth of the kidney is via

hyperplasia mainly in the tubules.

Evaluating the renal system in the

fetus

1st Trimester

• Bladder (megacystis 7-15mm, some might

resolve, >15mm most develop renal problems)

• MCDK, Meckel Gruber syndrome

37mm

Evaluating the renal system in the

fetus

2nd and 3rd Trimesters

• Amniotic fluid volume

• Localization of kidneys, characterization of

abnormalities

• Associated abnormalities. e.g, pulmonary

hypoplasia

• Bladder presence, normal/abnormal

• Renal arteries

Evaluating the renal system in the

fetus

2nd and 3rd Trimesters

• Amniotic fluid volume: ensure that the patient

is not leaking, mother is not taking drugs (ACE

inhibiters, NSAIDS), there is no PIH, there is

no fetal growth retardation.

• If normal Amniotic volume, at least one kidney

is functioning normally.

• If oligohydramnios, after excluding maternal

reasons, think of CAKUT

Specific Conditions

Agenesis/Aplasia

Agenesis Aplasia Hypoplasia

Bilateral renal agenesis

o Lethal anomaly 1:4000 births,

2.5:1 male preponderance

o Adrenals lie along the spine

o No renal arteries

Renal arteries

o Generally easy to see in a

longitudinal section.

o Visible as lateral branches

and absence means absent

kidney on that side

© Dr. Vikas Arora. India

© Dr. Prathima Radhakrishnan .

India© Dr. Ravi Kadasne. UAE

Unilateral renal agenesis

* marks empty

renal fossa

*

*All images © Dr. Prathima Radhakrishnan , India.

www.bangalorefetalmedicine.com

Unilateral renal agenesis

* marks empty

renal fossa

*

*All images © Dr. Ravi Kadasne. UAE

Ectopia, migration and fusion

anomalies

o Very common (1:500-2000)

o US is not very sensitive (~50%)

o Association with urologic, genital and

skeletal abnormalities, most common VUR

Clues

Angle of pelvis

Empty renal fossa

Actual fused kidneys

recognized

Hydronephrosis

o Commonest antenatal renal condition noted on US

o Often a transient finding

o Multiple etiologies, including urinary tract

obstruction, vesicoureteral reflux, aneuploidy

o If found antenatally, requires evaluation after birth

o Bilateral hydronephrosis seen in 20 to 40% of

cases

o 5% of individuals who have antenatal

hydronephrosis will require surgical intervention

Hydronephrosis

Woodward, M and Frank, D. Postnatal management of antenatal hydronephrosis.

BJU International 2002; 89(2): 149-156.

Physiologic (<5mm) 15%

Transient 48%

Ureteropelvic junction (UPJ) obstruction 11%

VUR 9%

Megaureter (Obstructed or unobstructed) 4%

MCDK 2%

PUV 1%

Other (ectopic ureter, prune belly, urachal cyst, and

urethral atresia)

8%

Significant post natal disease

with hydronephrosis

o 12% if <7mm 2nd trimester or <9mm 3rd

trimester

o 45%, if 7-10mm 2nd trimester or 9-15mm 3rd

trimester

o 88% if >10mm 2nd trimester or >15mm 3rd

trimester

Normal

Mild

hydronephrosis

Measuring

pyliectasiso Transverse section

o Ideally spine anterior

o Level of hilum

o “C” shaped kidney section

o Look for the widest point

between the “crura” of the

“C"

o Measure cortical thickness at

same section, use average if

measurements vary at different points

o Measure the AP thickness of the kidney

at its widest

© Dr. Gunjan Puri. India

© Dr. . Prathima

Radhakrishnan . India

Moderate hydronephrosis

Level of Obstruction

PUJ, VUJ, PUV

Megaureter

o Structural anomaly of

the distal ureter with

dysfunction or obstruction

o Males>Females,

can be bilateral

in 25%

o Need to differentiate

from gut

Perirenal urinoma

o PUJ obstruction, PUV

Posterior urethral valve

o Exclusively in males

o Total, partial or intermittent obstruction

o Sporadic, 1:5000, recurrence risk is small

o Persistently dilated bladder with a dilated

internal urethra giving “key-hole” bladder

appearance

o If prolonged and severe might result in renal

dysplasia, bladder rupture or fornicial

rupture with urinoma formation

Beaking of bladder

Renal cystic disease

o Dysplastic cysts

o Hereditary cysts

• Autosomal Dominant: Tuberous sclerosis, Von

Hipple-Lindau. ADPKD.

• Autosomal recessive: Meckel Gruber, Bardet

Biedl, Jeune, Short rib polydactyly. ARPKD

• Chromosomal: Trisomy 13, 18

o Non-dysplastic non-hereditary cysts

Multicystic Dysplastic Kidneys

o Ureteric/infundibulo-pelvic atresia

o Renal volume is replaced by cysts with

dense stroma in between but no renal

parenchyma

o Commonly unilateral, affected kidney is

nonfunctioning, survival depends on

contralateral kidney

o Vesicoureteral reflux is common (20%) in

the contralateral kidney

o Increased risk of hypertension

MCDK

13W

Normal MCDK

Hydronephrosis Multicystic dysplastic kidney

“Cysts” communicate Noncommunicating cysts

Cysts (calyces) are of similar size Cysts can be of different size

Anatomically aligned Random arrangement

Reniform shape maintained Irregular shape

Peripheral parenchyma might be present no recognizable parenchyma

MCDK and Hydronephrosis

together

H MCDK H

Autosomal Recessive Polycystic

Kidney Disease

o Kidneys increased in size with microcysts

Increased echogenicity with poor parenchymal

differentiation.

o Sometimes hypoechoic rim is identified

o Oligohydramnios; bladder may be absent empty

or small. Lungs may be hypoplastic

o ~1:25,000

o Intrauterine Demise or Early Neonatal Demise

Autosomal Dominant Polycystic

Kidney Disease

o Commonest hereditary renal cystic disease

o Usually not diagnosed antenatally as kidneys in utero

look normal.

o Rarely, symmetrically enlarged kidneys with small

cysts are noted

o Bladder is present

o Liquor is normal

o Recurrence rate 50%

o Scan parents

Meckel Gruber Syndrome

o Lethal

o 25% recurrence

o Autosomal recessive

o Early diagnosis (~ 10W)

o Triad of

• Encephalocele

• Cystic dysplastic kidneys

• Polydactyly

Echogenic kidneys

o Normal size

• Normal variant or

obstructive dysplasia

o Small

• Obstructive dysplasia

o Large

• ARPKD, ADPKD

Beckwith Wiedmann

and Perlman syndromes

Echogenic kidneys as a part of

Syndrome

Congenital renal masses

o Congenital nephroblastic nephroma,

commonest renal mass in the fetus and

newborn….benign tumour of the

mesenchymal cells

o Wilms tumour is of epithelial

origin and very rare

o Polyhydramnios is usual,

neonatal hypertension and

hypercalcemia

are possible © www.fetalultrasound.com/online/text/9-026.HTM

Fetal duplex kidney with upper

moiety hydronephrosis and

ureterocele

Bladder abnormalities

o Megacystis

o Ectopia vesicae

o Posterior Urethral Valve

o Congenital Diverticula

o Exstrophy

Thank You