1:500 to 1:1500 births
Failure of metanephric bud formation
Involution of MCDK
Association with other GU anomalies
Renal Agenesis
Diagnosed more often in females
from associated anomalies
Dx: 40% < 1 year, 75% < 5 years
Renal Agenesis
Radiographic Findings
Absent renal shadow
ectopic kidney vs. surgery vs. agenesis
Bowel loops in expected renal position
best by tomography
Enlarged contralateral kidney
Renal Agenesis
Ultrasound Findings
Neonatal/Prenatal adrenal flattened
may be mistaken for normal kidney
Absent renal unit
ectopic kidney vs. surgery vs. agenesis
May see associated GU anomalies
Renal Agenesis
Urographic/Angiographic findings
Absent function (look in pelvis)
Absent renal artery
Absent ureter and trigone
Contralateral enlargement
~ 15% with hypoplastic ureter
Renal Agenesis
Associated Anomalies
2 X increased contralateral kidney abnormal
Uterine Anomalies (unicornuate, bicornuate)
Seminal Vesicle, Vas Deferens and testicular anomalies/absence
PotterÕs Syndrome and bilateral agenesis
Others: VATER, TurnerÕs, Klippel-Feil
Errors of Renal Number
Renal Agenesis
Renal Hypoplasia
Supernumerary Kidney
Renal Hypoplasia
Rare
? Related to poor response of metanephric blastema to ureteral bud?
Difficult to distinguish from Acquired disease
Renal Hypoplasia
Xray Findings
Small or absent renal shadow
Normal excretion
Fewer calyces and nephrons
ÒA tiny kidneyÓ
No dysplastic or embryologic elements
Early division of ureteral bud
Blind-ending ureter if no contact with blastema
Length more than twice width
Enters main ureter at distinct angle
Uretero-ureteral reflux
Only removed if dilated or infected
Upper pole inserts ectopically, medial and caudal to lower pole ureter
Lower pole inserts orthotopically
Originated by
Carl Weigert, 1877
Robert Meyer, 1907 and 1946
Complete Duplication
Upper pole obstructs, lower pole refluxes
Incontinence in females
if ureter inserts below external sphincter
No incontinence in male
does not insert below external sphincter
Increased infection risk
Complete Duplication
Ultrasound
Two separate renal sinus echoes
May see discrepancy in dilatation
Not able to connect upper and lower pole collecting systems
Indirect: ectopic ureterocele in bladder
Complete Duplication
Urographic/CT findings
ÒDrooping LilyÓ sign
Separate collecting systems
Upper pole obstruction and/or
Lower pole reflux (horizontal insertion)
Ectopic ureterocele
Ectopic Ureterocele
1:2000 to 1:4000 births
Upper pole ostium often stenotic
dilated distal ureter
UTIÕs in majority, occasional incontinence
Dx usually in childhood
Ectopic Ureterocele
Radiographic findings
Early bladder filling defect (decreased function/drainage in upper pole)
May be difficult to see late in IVP
Cyst within cyst on US
Can drain into bladder or ectopically