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Sonographic Kidney Review Cheat Sheet (DRAFT) by

Sonography review of the kidney

This is a draft cheat sheet. It is a work in progress and is not finished yet.

Vocabulary

Nephron
Micros­copic functional unit of a kidney that forms urine.
Renal parenchyma
Consists of medulla and cortex
Renal cortex
Outer portion of kidney
Inner medulla
Contains pyramids and columns of Bertin
Columns of Bertin
Separates renal pyramids
Medullary pyramids
Transports urine to minor calyces.
Renal sinus
Contains renal hilum and collecting system
Renal hilum
Opening into sinus. Where blood vessels, nerves, lymphatics enter and exit the kidney.
Collecting system
Consists of minor and major calyces.
Minor calyces
Receive urine from medullary pyramids.
Major calyces
Receive urine from minor calyces and dumps urine into renal pelvis.
Renal pelvis
Holds urine before transp­orting it to the ureter.
Ureter
Transports urine to urinary bladder
Hydron­eph­rosis
Swelling of ureter
Morrison's pouch
Space that separates the right kidney and liver.
Renal Corpuscle
Consists of Bowmans capsule and glomerulus
Bowman's capsule
covers glomerulus
Glomerulus
Filters, connected to tubules.
Active transport
Requires cellular energy to move material
Passive transport
Material moves from high pressure to low pressure
Nephre­ctomy
Removal of kidney.
Compen­satory Hypert­rophy
Kidney enlarg­ement due to one kidney missing; it is compen­sating for the other one.
Hydron­eph­rosis
Abnormal accumu­lation of fluid within the kidneys.

Patient Prep

Transducer
3-5 MHz
Patient Position
Supine, RLD, LLD, prone
No patient prep unless if there will be a renal doppler study. If so then NPO for 6-8 hours.

Main Function

Filtra­tion:
get rid of waste products in blood
Produce Urine:
purify blood by secreting urine
Maintain homeos­tasis:
Regulate temper­ature and maintain water
Produces hormones
Note that the functional unit is the nephron!

Location

Retrop­eri­toneal:
Behind the peritoneum
Right kidney is lower than the left due to the liver
Posterior to the kidneys are
- Diaphragm - Psoas muscle - transv­ersus muscle - and quadratus lumborum
Anterior to right kidney
RLL, 2nd part duodenum, Morrison's pouch, hepatic flexure, jejunum or ileum of small bowel.
Anterior to left kidney
Stomach, tail of pancreas, spleen, Left adrenal gland, splenic flexure of colon.

Sonogr­aphic Appearance

Overall
Hetero­geneous
Renal Capsule
Hypere­choic, thin wall on the outside of the kidney
Renal Cortex
Homoge­neous. 1/3 less echogenic than the liver and spleen.
Renal Medulla
Anechoic; depending on urine.
Renal Sinus
Hypere­choic due to renal fat.
Renal Vascul­ature
Anechoic with echogenic walls
Ureters
Not seen on ultrasound unless if hydron­eph­rosis happens.

Measur­ements

Normal
Long: 9-13 cm
Wide: 5-7.5 cm
Thick: 2-3 cm
Abnormal
Long: less than 8 cm
Compen­satory Hypert­rophy
Kidney gets bigger if one was removed
Kidneys may shrink with age or renal disease.

Normal Variants

Dromedary Hump
Bulge on lateral border of kidney; most common on left kidney.
Hypert­rophied Column of Bertin
Column of Bertin extends into sinus of kidney
Duplicated Collecting System
Sinus is divided into 2 which may cause there to be 2 ureters as well.
Horseshoe kidney
Kidneys are connected; typically at lower poles.
Junctional Parenc­hymal Defect
Triangular echogenic area located anterior and superior.
Supern­umerary Kidney
More than 2 kidneys
Renal Agenesis
Absence of kidney; No kidney found
Renal Ectopia
Kidney is not located in its normal location; most commonly found at the pelvis.
Cross-­Fused Ectopia
Kidneys are on the same side
Extrarenal pelvis
Renal pelvis is outside of the renal hilum
Fetal Lobulation
Indent­ations between pyramids
 

Anatomy of Kidney (outer to inner)

Gerota fascia
Outer layer covering kidney and adrenal glands
Adipose capsule
fatty layer located in perine­phric space
True capsule
inner most layer
Renal parenchyma
Consists of cortex and medulla
- Cortex
Between true capsule and medulla; nephrons are located here
- Medulla
Consists of medullary pyramids and columns of Bertin.
Medullary pyramids
Pass urine to minor calyces
Column of Bertin
separates medullary pyramids
Renal Sinus
Consists of renal hilum and collecting system
- Renal Hilum
Space where arteries, veins, ureters, and lymphatic vessels enter
- Collecting system
Consists of calyces and renal pelvis
Minor calyces
Receive urine from medullary pyramids
Major calyces
Receives urine from minor calyces
Renal pelvis
Receives urine from major calyces. Reservoir for urine.
Ureter
Passes urine from renal pelvic into urinary bladder.

Divisions of the Kidney

The kidney is divided into 3 portions:
Cortex:
Outer portion, homoge­neous; darkest portion of kidney.
Contains: renal corpuscle, proximal and distal convoluted tubules.
Medulla:
Middle portion, anechoic
Contains: loop of henle, pyramids, and columns of bertin.
Sinus:
Central portion
Contains: Renal vein and artery, fatty tissue, nerves & lympha­tics.
Remember that the cortex and medulla make up the renal parenc­hyma.

Indica­tions for an Ultrasound

Urinary system obstru­ction
Enlarged ureters
Renal size
Comparison after therapy
Ultrasound guided biopsies or fluid aspiration
Abscess or hematoma
 

Protective Coverings

True (renal) Capsule
innermost layer, fibrous capsule.
Adipose Capsule
Middle layer, perirenal fat; anchors kidney to muscles
Gerota Fascia
Outer most layer, surrounds kidneys and adrenal glands.

Anatomy of Nephron

Nephron
Functional unit of a kidney; helps produce urine.
Afferent arteriole
Sends blood to glomerulus
Glomerulus
Filters blood, passive transport
Efferent arteriole
Carries blood out of glomerulus
Bowmans capsule
Surrounds glomer­ulus, filtrate (ion, amino acids, sodium, glucose) enters into capsule.
Proximal convoluted tubule
Reabso­rption of useful substa­nces; water, glucose, vitamins, amino acids etc. (active transp­ort).
Loop of henle
Consists of ascending and descending limbs.
Ascending limb
Makes medulla salty
Descending limb
Permeable to water (water leaves loop for reabso­rpt­ion).
Distal convoluted tubule
Reabso­rption, dumps waste into collecting ducts.
Collecting ducts
Waste enters then goes into ureters.

Vascul­ature

Renal artery
Located at hilum
Segmental (lobar) artery
Sinus
Interlobar artery
Between pyramids
Arcuate artery
Base pyramid
Interl­obular artery
Cortex
Afferent arterioles
Cortex
Glomerulus
Cortex
Efferent arteriole
Cortex
Peritu­bular capill­aries
Cortex
Vasa recta
Interl­obular vein
Cortex
Arcuate vein
Base pyramid
interlobar veins
Between pyramids
Segmental (lobar) veins
Sinus
Renal vein
Hilum