Diagnostic Imaging of Congenital Renal Anomalies

1. Genito-Urinary System
Congenital Renal Anomalies

2. Mohamed Zaitoun
Assistant Lecturer-Diagnostic Radiology
Department , Zagazig University Hospitals
Egypt
FINR (Fellowship of Interventional
Neuroradiology)-Switzerland
zaitoun82@gmail.com

5. Knowing as much as
possible about your enemy
precedes successful battle
and learning about the
disease process precedes
successful management

6. Congenital Anomalies
a) Anomalies related to Position
b) Anomalies related to Form
c) Anomalies related to Number
d) Ureteroplevic Junction Obstruction
e) Anomalies related to Vascular Development
f) Anomalies related to Bladder Development
g) Anomalies related to Urethral Development

7. a) Anomalies related to Position :
1-Plevic Kidney
2-Ectopic Kidney

8. 1-Plevic Kidney :
-Failure of the kidney to ascend during
embryologic development results in a pelvic
kidney
-These kidneys are often small and abnormally
rotated
-Blood supply is from the iliac artery or the aorta
-These kidneys are prone to poor drainage and
may develop dilation of the collecting system
with susceptibility to infection & stone formation

12. Ectopic pelvic kidney, Volume rendering (a) demonstrates absence of the left
kidney at the left renal fossa, instead, an ectopic left pelvic kidney is seen,
the axial contrast-enhanced MDCT image (b) shows an engorged left iliac
vein (asterisk), due to left aberrant renal vein (not shown), the ectopic
kidney receives blood supply from two renal arteries arising form the aorta
(arrowhead) and left iliac artery (arrow)

17. 2-Ectopic Kidney :
-If the kidney ascends too high , it may pass
through the foramen of Bochdalek and
become a true thoracic kidney
-Can also be presacral or at the lower
lumbar level

22. b) Anomalies related to Form :
1-Horseshoe Kidney
2-Pacake / Discoid Kidney
3-Crossed Renal Ectopia
4-Rena Hypoplasia
5-Fetal Lobulation
6-Compensatory Hypertrophy

23. 1-Horseshoe Kidney :
-Most common fusion anomaly
-Two kidneys joined by parenchymal/fibrous
isthmus
-Fusion of right & left kidneys at lower pole in 90 %
-Bilateral malrotation
-Associated with other anomalies in 50 % (e.g.
vesicoureteric reflux , ureteral duplication ,
genital anomalies & Turner’s syndrome)

24. -Radiographic Features :
1-Abnormal axis of each kidney with lower
calyx more medial than upper calyx
2-Bilateral malrotation of renal pelvises in
anterior position
3-Isthmus lies anterior to aorta and inferior
vena cava (IVC) but behind inferior
mesenteric artery (IMA)

29. Horseshoe kidney with anteriorly oriented renal pelvis, axial contrast-
enhanced MDCT image (a) shows a horseshoe, the renal isthmus is
found anterior to the great retroperitoneal vessels, corresponding
volume rendering (b) better show the inferior renal isthmus, the
normal renal arteries, and the anterior location of the renal pelvises

32. I = isthmus, IMA (arrow)

33. -Other anomalies related to orientation :
Renal malrotation

34. Malrotated kidney about the horizontal axis, axial contrast-enhanced
MDCT image (a) and volume renderings (b, c) show a malrotated
right kidney about the horizontal axis, with a medially located pelvis

35. Anterior malrotated kidney, axial (a) and sagittal (b) contrast-enhanced
MDCT images show an anterior malrotated left kidney with
pelvicaliceal stones, volume rendering (c) shows stones in anteriorly
oriented renal pelvis

36. Lateral malrotated kidney, axial maximum intensity projection (a) and
volume rendering (b) show a lateral malrotated right kidney, the
renal pelvis shows abnormally lateral location

37. 2-Pacake / Discoid Kidney :
-Bilateral fused pelvic kidneys , usually near
the aortic bifurcation

39. Pancake kidney with APKD

40. 3-Crossed Renal Ectopia :
-Both kidneys are found in the same side
-In 85-90 %of cases , the ectopic kidney will
be fused to the other side
-The upper pole of the ectopic kidney is
usually fused to the lower pole of the other
kidney , although fusion may occur
anywhere

45. 4-Rena Hypoplasia :
-The kidney is small but otherwise normal
and with normal renal function
-Patients with bilateral hypoplasia often
have evidence of renal insufficiency

46. Hypoplastic functional kidney, axial (a) and coronal (b) maximum
intensity projections, and volume rendering (c) show a right
hypoplastic functional kidney and a hypertrophied left kidney with
incompletely duplicated pelvicalyceal system

47. Hypoplastic non-functional kidney, axial contrast-enhanced MDCT
image (a) and coronal maximum intensity projection (b) show a left
hypoplastic non-functional kidney (arrow) and a hypertrophied right
kidney

48. 5-Fetal Lobulation :
-Multiple indentations of the renal cortex
with no evidence of fibrotic tissue (would
be seen as hyperechoic bands)
-There is no evidence of thinning of the
renal cortex or deformity of the
pelvicalyces (ruling out chronic
pyelonephritis)

49. Fetal renal lobulation, coronal maximum intensity projections (a, b)
show persistent fetal lobulation in both kidneys

50. 6-Compensatory Hypertrophy :
-Occurs when existing healthy nephrons enlarge to
allow the healthy renal parenchyma to perform
more work
-Seen in :
a) Nephrectomy
b) Renal agenesis
c) Renal hypoplasia
d) Renal atrophy
e) Renal dysplasia

51. Renal agenesis with compensatory hypertrophy of the right
kidney

52. c) Anomalies related to Number :
1-Unilateral Agenesis
2-Bilateral Renal Agenesis
3-Supernumerary Kidney
4-Duplex Collecting System & Ureterocele
5-Congenital Megacalices
6-Congenital Megaureter

53. 1-Unilateral Agenesis :
-Increased incidence of extrarenal
abnormalities (meningomyelocele , VSD ,
intestinal tract strictures , imperforate anus
, unicornuate uterus & skeletal
abnormalities)
-The other kidney shows compensatory
hypertrophy

54. Renal agenesis, Coronal maximum intensity projection (a) and volume
rendering (b) demonstrate absence of the left kidney and
compensatory hypertrophy of the right kidney, which shows a
cortical cyst, the left main renal artery was absent

56. 2-Bilateral Renal Agenesis :
-Potter syndrome
-Fatal in first few days of life due to
pulmonary hypoplasia secondary to the
associated oligohydramnios

57. 3-Supernumerary Kidney :
-Very rare
-Most common on the left side caudal to
normal kidney

60. 4-Duplex Collecting System & Ureterocele :
-Duplex collecting system is the most common
congenital anomaly of the urinary tract
- The degree of duplication is variable , duplication
is complete when there are two separate
collecting systems and two separate ureters ,
each with their own ureteral orifice , duplication
is incomplete when the ureters join and enter the
bladder through a single ureteral orifice

61. Complete duplicated collecting system

62. Bilateral complete duplicated collecting system

63. Incomplete duplicated collecting system, coronal maximum intensity
projection (a) and volume rendering (b) show an incompletely
duplicated left pyelocalyceal system and ureter, the left ureters
converge and fuse near the bladder

64. Incomplete duplicated collecting system

65. -In complete obstruction , the ureter draining
the lower pole has a more perpendicular
course through the bladder wall making it
more prone to reflux , the ectopic ureter
from the upper pole is prone to obstruction
, reflux or both , if obstruction is present it
can result in cystic dilatation of the
intramural portion of the ureter giving rise
to a ureterocele

67. -Ureterocele :
a) Definition
b) Types
c) Radiographic Features

68. a) Definition :
Herniation of the distal ureter into the bladder
b) Types :
1-Simple : 25 %
-Normal location of ureter (at a VUJ)
-In adults
2-Ectopic : 75 %
-Abnormal location of ureter
-Unilateral with duplication

69. c) Radiographic Features :
1-IVP :
-Filling defect in the bladder on IVP (cobra head sign)
2-Ultrasound :
-cystic structure projecting into the bladder, often near the
normal location of the vesicoureteric junction (VUJ)
-This is ectopic in the majority of cases and therefore not at
the expected location of the ureteric orifice, the
associated ureter is usually noticeably dilated
3-MCUG :
-Round or oval lucency near the trigone

70. Cobra head sign

74. Ureterocele, early anteroposterior voiding cystourethrography (VCUG)
demonstrates small ureterocele

75. Ureterocele, coronal curved (a) and axial (b) contrast-enhanced MDCT
images show distal ureter balloons at its opening into the bladder,
forming a sac-like pouch

76. Simple ureterocele, (a) IVU image shows the typical cobra head appearance at
the end of both ureters (arrowheads), = bladder,★ (b) IVU image shows the
contrast material-filled bladder ( ) with a negative filling defect (arrowheads)★
that represents a ureterocele, (c) Transverse US image of the bladder (B)
demonstrates a sonolucent cystic structure with an echogenic wall (U) that
projects into the bladder

77. Ectopic ureterocele in a 3-month-old boy, (a) IVU image shows a duplex left kidney, there
is nonvisualization of the upper moiety and moderate dilatation of the lower pole
pelvicaliceal system ( ), note the increased distance between the spinal column and∗
the left kidney produced by the upper moiety, a large filling defect (u) is seen in the
bladder, a finding that represents a ureterocele, (b) Longitudinal US scan through the
bladder shows a rounded, well-defined cystic mass (u) that represents an ectopic
ureterocele

78. 5-Congenital Megacalices :
-Is an entity producing nonobstructive
enlargement of the calices which is usually
unilateral
-The most common association is with
primary megaureter

79. MIP Image of a CT urogram shows numerous dilated, polygonal-shaped
calyces in the left kidney with convex outer margins (red arrows), the
calyces fit together like pieces of a puzzle. The renal pelvis (white arrow) is
not dilated and the ureter is normal in size (yellow arrow) helping to
differentiate this from a cause of obstructive hydronephrosis

80. 6-Congenital Megaureter :
-Results in functional ureteric obstruction
-Men are more commonly affected as is the
left side

81. Primary megaureter in a 7-month-old boy, longitudinal US image
through the bladder ( ) demonstrates a dilated distal ureter (★ u) and
a narrowed juxtavesical ureteral segment corresponding to the
aperistaltic segment (arrow)

82. Primary megaureter in a neonate with hydroureteronephrosis at
prenatal US, (a) Transverse US image through the bladder ( )★
shows a markedly dilated and tortuous ureter (u), (b) IVU image
shows the dilated and tortuous left ureter (u) with slight
hydronephrosis, = bladder★

83. d) Ureteroplevic Junction Obstruction :
-Common anomaly and is found in men with
a 2:1 predominance
-The left kidney is affected twice as
frequently as the right
-Often marked ballooning of the renal pelvis
is present and if long-standing , there will
be associated renal parenchymal atrophy
and the ureter is of normal caliber

84. Ureteropelvic junction stenosis, coronal maximum intensity projections
(a, b) show left ureteropelvic junction stenosis, close to crossing
vessels of uncertain involvement (arrow), pyelocalycial dilatation
and decreased cortical nephrogram are seen

85. e) Anomalies related to Vascular
Development :
1-Aberrant vessels
2-Retrocaval ureter

86. 1-Aberrant vessels
-As the kidney ascends during embryologic
development , it derives its blood supply from
the aorta at successively higher levels with
regression of the lower level vessels
-If the lower level vessels persist , aberrant renal
arteries will be present
-Aberrant vessels can compress the ureter
anywhere along its course , giving rise to
obstruction
-With color Doppler , aberrant vessels may be
seen crossing the ureter at the level of ureteric
obstruction

87. (a) Excretory urogram after 30 min shows severe dilatation of the right pelvocalyceal
system with cortical thinning and smooth obstruction of the right ureteropelvic
junction, (b) CTA with a maximum intensity projection technique demonstrates two
renal arteries originating from the aorta, an inferior aberrant artery (arrow) is crossing
over the ureteropelvic junction

88. 2-Retrocaval ureter
-Also known as circumcaval ureter
-Rare but well recognized congenital anomaly ,
there is a 3:1 predominance in men , with most
patients presenting with pain in the 2nd
to 4th
decade of life
-Right ureter swings medially over pedicle of L3/4,
passes behind IVC, then exits anteriorly
between IVC and aorta returning to its normal
position, produces varying degrees of proximal
hydroureteronephrosis

92. Intravenous urogram showing right-sided hydronephrosis and the
dilation of the proximal ureter up to the level of the L3 transverse
process, the medial deviation of the ureter at this level (arrow) gives
rise to the typical fish hook or reversed S appearance

93. CT+C showing (A) the dilated right ureter (U) proximal to its obstruction, the
ureter follows a medial course at this level (solid arrow), posterior to the
inferior vena cava (C), at a lower scan (B), the retrocaval location of the
right ureter is medial compared with the normal location of the left ureter
(dashed arrow)

94. CT scan below the level of the kidneys demonstrates a more medial
retrocaval placement of the right ureter

96. f) Anomalies related to Bladder
Development :
1-Agenesis
2-Duplication
3-Exstrophy
4-Prune Belly Syndrome
5-Bladder Diverticula
6-Urachal anomalies

97. 1-Agenesis :
-Is a rare anomaly , most infants with
bladder agenesis are stillborn with virtually
all surviving infants being female
-Often , many associated anomalies are
present
-U/S :
*The bladder is absent

98. Agenesis of the bladder in a 5-day-old girl with wetting, image from
bilateral ureterography performed with catheters placed in ectopic
ureteral orifices shows dilated and tortuous ureters (u) with dilatation
of the renal pelves and calices, intrarenal reflux is also noted, IVU
showed poorly functioning hydronephrotic kidneys

99. 2-Duplication :
-Three types :
*Type 1 >>
-A peritoneal fold separates the two bladders
*Type 2 >>
-An internal septum is present dividing the bladder
*Type 3 >>
-There is a transverse band of muscle dividing the
bladder into two unequal cavities

100. Complete duplication of the bladder and urethra in the coronal plane, (a) Lateral
retrograde cystourethrogram through both separate urethral openings
shows two bladders, one (a) anterior to the other (b), (b) Transverse US
image also shows the two bladders (a, b), one lying in front of the other and
each with its own muscular wall

101. 3-Exstrophy :
-There is 2:1 predominance in males
-Also known as ectopia vesicae, refers to a herniation of
the urinary bladder through an anterior abdominal wall
defect
-Failure in development of the mesoderm below the
umbilicus leads to absence of the lower abdominal and
anterior bladder wall
-Imaging findings include a soft-tissue mass extending from
a large infra-umbilical anterior wall defect which may be
close to the umbilical arterial exits, the absence of a
normal urinary bladder and a low-lying umbilical cord
insertion may also indicate the diagnosis
-Failure of the pubic bones to meet in the midline
(widened pubic symphysis), this appearance on AP plain
radiograph of the pelvis (manta ray sign)

103. 4-Prune Belly Syndrome :
-Rare anomaly comprising a specific constellation of
features
-It consists of three major findings :
1-Gross ureteric dilatation
2-Anterior abdominal wall underdevelopment (resulting in
the prune belly appearance)
3-Bilateral undescended testes (cryptorchidism) in males
-There is often an association with other respiratory,
gastrointestinal, musculoskeletal, and cardiovascular
anomalies
-It is also known as Eagle Barrett syndrome or triad
syndrome

104. -Urinary tract abnormalities include :
1-Bilateral hydroureteronephrosis: often with
extremely dilated, tortuous ureters
2-Varying degrees of renal dysplasia
3-Enlarged urinary bladder, often with urachal
diverticulum
4-Vesicoureteral reflux is common
5-Poor bladder contractility
6-Dilated posterior urethra without urethral
obstruction

105. Supine frontal view of abdomen, the right flank is bulging with very little
abdominal wall tissue covering the air-filled right flank bowel loops.,
the ribs have a transverse orientation, sometimes referred to as a
'coat-hanger' deformity

106. The abdomen of an infant with prune belly syndrome shows marked
distention of the abdomen and bulging flanks secondary to a large
urinary system and the absence of abdominal wall musculature

108. (a) Oblique radiograph bladder, (b) voiding urethral film, a urachal
diverticulum (arrow) is seen at the dome of the urinary bladder, the
urethra is tortuous with a dilated prostatic urethra (arrowhead)

109. Prune-belly syndrome, IVU (a) and VCUG (b) images show the characteristic
large floppy bladder ( ) and marked bilateral hydronephrosis and★
hydroureter (u) with renal parenchymal wasting, note the anomalies in the
pelvic bones and both femurs due to renal osteodystrophy in b

110. 5-Bladder Diverticula :
-Outpouchings from the bladder wall, whereby mucosa
herniates through the bladder wall
-They may be solitary or multiple in nature and can very
considerably in size
-May be congenital (primary) or acquired (secondary)
-A Hutch diverticulum is a congenital bladder diverticulum,
seen at vesicoureteric junction
-Acquired diverticula are more common, usually occurring
the context of a trabeculated bladder, resulting from
chronic bladder outlet obstruction

115. A view from a voiding cystourethrogram demonstrates two large
bladder diverticula (D) flanking the bladder lumen (B), these
diverticula are in the region of the insertion of the ureters, they are
frequently associated with reflux (Hutch diverticula) but no reflux
was demonstrated in this patient

121. 6-Urachal anomalies
-Normally, the urachus closes in the last half of fetal life
-There are 4 types of congenital urachal anomalies :
a) Patent urachus (50 %)
b) Urachal cyst (30 %), forms if the urachus closes at the
umbilical and bladder ends but remains patent in
between, the cyst is usually situated in the lower one
third of the urachus
c) Urachal sinus (15 %), forms when the urachus closes at
the bladder end but remains patent at the umbilicus
d) Urachal diverticulum (5 %), forms if the urachus closes
at the umbilical end but remains patent at the bladder
-There is 2:1 predominance in males

127. Patent urachus

128. Urachal remnant, sagittal contrast-enhanced MDCT image shows an
urachal remnant (arrows), traveling from the anterior-superior
aspect of the bladder into the umbilical region

129. Urachal cyst

130. Urachal sinus

131. Vesicourachal diverticulum as an incidental finding in a 58-year-old man, (a, b) Axial CT
scans (a obtained at a lower level than b) demonstrate a small, anterosuperior
outpouching (arrow) representing a urachal diverticulum arising from the apex of the
bladder (bl), the umbilicovesical fascia (arrowheads in b) allows localization of the
urachus in the extraperitoneal perivesical space, (c) Sagittal US image shows a
localized hypoechoic outpouching (arrow) communicating with the uppermost portion
of the bladder (bl), thereby helping confirm the CT findings

132. g) Anomalies related to Urethral
Development :
1-Diverticulum
2-Male Hypospadias & Epispadias
3-Posterior Urethral Valve

133. 1-Diverticulum :
-The majority of urethral diverticula are
acquired through injury or infection ,
although some are congenital
developmental anomalies
-More frequently in women than in men
-A uretheral diverticulum is a cystic lesion
that typically arises from the posterolateral
mid or distal urethra

139. 2-Male Hypospadias & Epispadias :
-Hypospadius : Ectopic ending of the urethra on
the ventral aspect of the penis , scrotum or
perineum
-Hypospadias is the result of a defective midline
fusion of the genital folds
-Epispadias : The urethral meatus is located
dorsally on the penile shaft
-Hypospadius Associations :
a) Cryptorchidism , 30%
b) Inguinal Hernias , 10%
c) Urinary Tract Abnormalities
-Epispadias can be isolated or seen as part of the
exstrophy-epispadias complex

140. Penile hypospadias with meatal stenosis in a 10-year-old male
presenting with a short phallus and thin urinary stream, an oblique
VCUG image reveals a uniformly dilated urethra up to the tip
(arrows) and abrupt narrowing of the urinary stream at the
hypospadiac meatus (arrowhead)

141. Oblique VCUG image of a young male shows a short epispadiac
urethra opening on the dorsal surface of the penile shaft (arrow)

142. IVU image of a child with bladder exstrophy shows pubic diastasis,
note the lack of a well-formed bladder (contrast from the ureters can
be seen escaping out on to the skin surface)

143. 3-Posterior Urethral Valve :
-Congenital folds (thick folds > thin folds) located
in the posterior urethra
-The most common congenital obstructive lesion of
the urethra and a common cause of obstructive
uropathy in infancy
-U/S shows : the bladder is typically thick walled
and trabeculated with an elongated and dilated
posterior urethra (keyhole sign)

147. -Voiding Cystourethrogram (VCUG) shows :
a) Dilatation and elongation of the posterior
urethra (equivalent of the
ultrasonographic keyhole sign)
b) Linear radiolucent band corresponding to
the valve (only occasionally seen)
c) Vesicoureteral reflux (VUR) , seen in 50%
of patients
d) Bladder trabeculation / diverticula

148. Oblique VCUG image shows a dilated posterior urethra (arrow) with an
abrupt transition to a normal-calibre anterior urethra, note the
bladder neck hypertrophy, the irregular trabeculated bladder wall,
and the left-sided grade III vesicoureteric reflux (curved arrow)

149. Oblique VCUG image shows a dilated posterior urethra
(arrow) and a trabeculated urinary bladder