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ABDOMINAL SONOGRAPHY 1
LECTURE 9
THE KIDNEY AND URINARY
TRACT PART 1
Outline
Urinary Tract
Part I of II
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Normal anatomy
Anatomical Terminology
Renal Congenital abnormalities
Ectopic Kidney
Horseshoe Kidney
Cross fused Renalo Ectopia
Fused pelvic kidney
Dromedary Hump
Junctional Parenchymal defect
Duplex Kidney
Column of Bertin
Renal Agenesis
Extrarenal Pelvis
Posterior Urethral Valves
Renal cysts
Atypical renal cysts
Autosomal Dominant Polycystic kidney disease
Autosmal recessive polycystic kidney disease
Multicystic Dysplastic kidney
Normal Anatomy
 The
paired kidneys and ureters are
retroperitoneal, lying against the deep
muscles of the back. The right is slightly
inferior in location as compared to the left,
mostly due to the liver’s location on the right.
 In relation to the right kidney, the:
 Adrenal gland is superomedial
 Liver is superolateral
 Right colic flexure is inferior
 2nd portion of the duodenum is medial
The right kidney
Gerota’s Fascia
The large intestine
 In relation to the left kidney, the:
 Adrenal gland and spleen are superior
 Pancreatic tail is anterior to the upper pole
 Left colic flexure is inferior
 The diaphragm, psoas muscle, and quadratus
lumborum muscle are on the posterior aspect
of the kidneys
Diaphragm, psoas muscle
Psoas
 At the hilum of the kidney:
 Vein exits anteriorly
 Artery enters between vein and ureter
 Ureter exits posteriorly
The renal hilum (transverse)
Transverse kidney w/vein
 Echogenicity
 Renal cortex is isoechoic or hypoechoic
 Medullary pyramids are anechoic
 Reanl sinus is hyperechoic
Echogenicity of the kidney
Anatomical Terminology
 Renal cortex -outer reanl parenchyma from
renal sinus to renal capsule (normal= > 1 cm
 Renal medulla- inner portion of kidney from
base of pyramids to center of kidney.
 Renal sinus-inner hyperechoic portion of
kidney which contains fat, calyces, renal
pelvis, connective tissue, renal vessels, and
lymphatics
Renal cortex, medulla
 Medullary
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pyramids- anechoic, equally
spaced triangles of collecting tubules
between cortex and renal sinus. Commonly
seen in neonatal and pediatric kidneys.
Renal pelvis- funnel shaped transition from
the major calyces to the ureter.
Renal hilum – medial opening from entry /
exit of artery, vein, and ureter.
Major calyces- 3 extensions for the renal
pelvis
Minor calyces- extensions of the major
calyces that collects urine from the medullary
pyramids.
Medullary pyramids, Renal pelvis, renal hilum, major and
minor calyces.
 Renal papilla – apex of medullary pyramids.
 Gerota’s fascia – fibrous sheath enclosing
kidney and adrenal glands. This is also
referred to as the perirenal space.
 Nephron- functional unit of kidney consisting
of the renal corpuscle, proximal convoluted
tubule, descending and ascending limbs of
Henle’s loop, distal convoluted tubule, and
collecting tubules.
 Renal corpuscle (Malpighian body) – consist
of glomerulus and glomerular capsule
(Bowman’s capsule).
Renal Papilla, Gerota’s fascia, Nephron, Renal
Corpuscle.
RENAL VASCULATURE
 The kidneys are supplied with arterial blood
via the main renal artery which branches off
the aorta.
 At the hilum, the main renal artery divides
into 5 segmental arteries.
 At the level of the medullary pyramids, the
segmental arteries divide into the interlobar
arteries which travel perpendicular to the
renal capsule.
 At the base of the medullary pyramids, the
arcuate arteries branch from the interlobar
arteries in the manner that is parallel to the
renal capsule. Typically the arcuate arteries
are difficult to obtain an ideal spectral
waveform
as
they
typically
travel
perpendicular to the Doppler sound beam.
 The interlobular arteries are the smallest
renal arteries that branch off the arcuate
arteries running perpendicular to the renal
capsule.
Main renal
Segmental
Interlobar
Arcuate
Interlobular
Renal blood flow
Renal congenital abnormalities
 Embryologically, the kidneys originate in the
pelvis and ascend into the upper abdomen so
that the upper pole of each kidney is more
medial than the lower pole (an inverted “V”).
 Congenial anomalies of he genitourinary tract
are more common than any other organ system.
 Complications (Obstruction, stasis) associated
with congenital abnormalities include:
 Impaired renal function
 Infection
 Calculus formation
Ectopic Kidney
 The word ectopic means displaced or in a
location away from the normal position.
 An ectopic kidney results from failure of the
kidneys to ASCEND into the abdomen.
 Often, an ectopic kidney is also referred to as
a pelvic kidney.
 With ectopic kidneys, there is an increased
incidence of UPJ (Ureter-Pelvic Junction)
obstruction, ureteral reflux, and multicystic
renal dysplasia.
Ectopic kidney
Horseshoe kidney
 Most common fusion anomaly in which the
lower poles typically connect across the
midline anterior to the aorta.
 The larger U-shaped kidney lies lower in the
abdomen because ascent is prevented by the
inferior mesenteric artery.
 Sonographically, the isthmus or connection
anterior to the aorta is frequently mistaken
for lymphadenopathy. The ureter is typically
located anterior to the isthmus.
Horseshoe kidney
Crossed fused renal ectopia
 The developing kidneys fuse in the pelvis and
one kidney ascends to its normal position,
carrying the other one with it across the
midline.
 Two kidneys are visualized on one side of the
abdomen with absence of a contralateral
kidney.
 Ureters connect on both sides of the bladder
thus one ureter crosses the midline.
Cross fused renal ectopia
Examples of Cross-Renal ectopia (only D is fused)
A. Bilaterally crossed
B. S-Shaped
C. L-Shaped
D. Disc kidney
Fused pelvic kidney
 Kidneys may fuse to form a round mass in the
pelvis know as a discord or pancake kidney.
Fused pelvic kidney/Pancake
kidney
Dromedary Hump
 A common variant of cortical thickening on
the lateral aspect of the left kidney.
 Make certain the “hump” has the same
echogenicity as the rest of the renal cortex.
Dromedary Hump
Junctional parenchymal defect
AKA Fetal lobulation
 Sonographically
seen as a triangular
hyperechoic area on the anterior aspect of
the upper pole of he right kidney.
 This defect is also known as fetal lobulation,
which is partial fusion of the embryonic
kidney.
Junctional Parenchymal Defect
Duplex Kidney
 This is a duplication of the collecting system which
occurs in approximately 15% of the population. The
duplication may be:
 Complete – two ureters
 Incomplete – one ureter
 Sonographically, a duplex kidney is typically longer
than normal and has a complete central cortical
break within the hyperechoic sinus.
 With complete double ureters, the ureter draining
the upper pole typically inserts in an ectopic location
on the bladder. A frequent complication of ectopic
ureter is a ureterocele; a prolapse of the distal ureter
into the bladder. This will result in hydroureter and
hydronephrosis of the upper collecting system of the
kidney.
Duplex kidney
Duplex kidney
Column of Bertin
 Hypertrophy of the renal cortical parenchyma
located between two medullary pyramids.
This may give the appearance of a mass
effect although the echogenicity is equal to
the peripheral cortical tissue.
Column of Bertin
Renal Agenesis
 Bilateral renal agenesis is associated with
oligohydramnios and pulmonary hypoplasia.
It is incompatible with life.
 Unilateral renal agenesis is frequently
associated with:
 Bicornuate uterus in females
 Seminal vesicle agenesis in males.
 Compensatory hypertrophy of the solitary
kidney maintains normal renal function.
Extrarenal pelvis
 The renal pelvis normally is located within the
renal sinus.
 An extrarenal pelvis lies outside the renal
sinus sonographically appearing as a cystic
collection medial to the renal hilum.
Extrarenal pelvis
Posterior Uretheral Valve
 Posterior urethral valve is a common cause of
urinary obstruction in the male neonatal patient.
 This obstruction is due to a flap of mucosa that
has a slit-like opening in the area of the prostatic
urethra.
 Sonographic findings include:
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Large bladder
Hydroureter
Hydronephrosis
Urinoma (an encapsulated collection of extravasated
urine- typically found in the area adjacent to the
kidneys)
 Keyhole sign (in the pelvis)
PUVs
Renal cysts
 Simple renal cysts occur in 50% of people
over the age of 50.
 Sonographic criteria include:
 Acoustic enhancement
 Absence of internal echoes
 Sharply defined thin wall
 Round or oval shape
 Most renal cysts are simple cortical cysts that
originate from obstructed uriniferous tubules.
 Types of renal cysts include:
 Pylogenic
cystscalyceal
diverticula
that
sonographically appear as a simple cyst.
 Parapelvic cysts- cortical cysts that bulge into the
central sinus of the kidney.
 Paripelvic cysts- lymphatic cysts in the central sinus.
 Sonographically, the different types of renal
cysts can not be distinguished. Ultrasound
determines the location of the cyst.
 Cortical or parenchymal cysts – renal cysts located in
the periphery of the kidney.
 Peripelvic cysts- renal cysts located in the center
(RENAL SINUS) of the kidney.
 A renal psuedoaneurysm may mimic a simple
cyst and is typically associated with a history of
renal biopsy or trauma.
Simple renal cyst
Parapelvic cyst
Parapelvic cysts that could
be mistaken for a dilatated pelvicalyceal system
Hemorrhagic renal cyst
Atypical renal cysts
 Cysts with a single thin septation, minimal
wall calcification, internal echoes caused by
artifact or lobulated shapes may all be
associated with simple benign cysts.
 Characteristics that are atypical and may
suggest a malignant cystic lesion include:
 Multiple thick septation
 Irregular walls
 Solid component
 These
cysts should require histological
confirmation (FNA) for definitive diagnosis.
Atypical renal cyst/
complex renal cyst
 Autosomal dominant:
 One of several ways that a trait or disorder can be
passed down through families. A pattern of
inheritance in which an affected individual has one
copy of a mutant gene and one normal gene on a
pair of Autosomal chromosomes.
 Autosomal recessive:
 A genetic condition that appears only in
individuals who have received two copies of an
Autosomal gene, one copy from each parent.
Autosomal Dominant (adult) polycystic
kidney disease: APKD
 Bilateral renal enlargement due to the
development of numerous cysts of varying sizes.
 Associated with cysts in the liver, pancreas, and
spleen.
 Multiple renal cysts may be identified as early as
20-30 years of age.
 Destruction of the residual renal tissue in
advanced stages leads to renal failure and
hypertension.
 Associated with arterial aneurysms especially
cerebral arterial (Berry) aneurysms of the circle
of Willis.
Adult polycystic kidney disease
Autosomal recessive (infantile)
Polycystic kidney disease AKA IPCKD
 Sonographic findings include:
 Enlarged kidneys bilaterally
 Hyperechoic parenchyma
 Loss of cortical medullary distinction
 Sonographic appearance is due to multiple
small cysts throughout the kidney. These
cysts result from cystic dilation of the
collecting tubules secondary to hyperplasia of
eth interstitial portions of the ducts.
 Associated with
 Renal dysfunction
 Pulmonary hypoplasia
 Periportal fibrosis
 Portal hypertension
 Autosomal recessive polycystic kidney
disease may be detected in utero with
oligohydramnios.
IPCKD
Multicystic Dysplastic Kidney
 Most common cause of abdominal mass in
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NEWBORNS.
It is typically unilateral, although may be bilateral.
This non-functioning kidney consists of noncommunicating cysts with the absence of renal
parenchyma.
Usually the result of atresia of the uretro-pelvic
junction during fetal development.
Associated renal anomalies include:
 Contralateral UPJ obstruction.
 Contralateral renal agenesis or hypoplasia
 Horseshoe kidney
Multicystic Dysplastic Kidney
Neonate
Diagnostic Medical Sonography Program
Abdominal Sonography I
Urinary Tract Part I of II
Homework
 Define a hypertrophied Column of Bertin and show an
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image of it.
What is a duplex collecting system and how an image of it.
What is multicystic dysplastic kidney and show several
images of it.
Explain the scanning technique for imaging the kidneys
with ultrasound. Include in your answer imaging the renal
arteries.
Explain the anomalies related to the ascent of the kidney.
Provide an image of a horseshoe kidney.
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Name three notable structures posterior to the kidneys.
What is the orientation of structures that enter and exit the renal hilum?
Trace the branches or the renal artery.
Name the fascia which encloses the kidneys, adrenal glands, and perinephric
fat.
What renal structure is a concentrated area of collecting tubules which is
sonographically seen in newborns and infants as hypoechoic equally space
triangles.
Bilateral renal agenesis associated with Oligohydramnios and pulmonary
hypoplasia is incompatible with life. What is associated with UNILATERAL
renal agenesis?
Describe the development and sonographic appearance of crossed renal
ectopia and crossed fused renal ectopia.
Describe the development and sonographic appearance of a horseshoe kidney.
A duplex kidney is discovered with dilation of the upper pole collecting system.
In this situation, is there partial or complete ureter duplication?
What is the most common cause of urinary obstruction in male neonates?
What are the sonographic findings of urinary obstruction in male neonates?
Describe the appearance of a dromedary hump.
Describe the appearance of a junctional parenchymal defect.
Describe the appearance of eh column of Bertin.
Describe the appearance of an extra renal pelvis.