Urinary System: Renal and Bladder

what does the urinary system consists of?

• kidneys

• ureter

• urinary bladder

• urethra

what makes up the upper urinary tract?

kidneys and ureter

what makes up the lower urinary tract?

urinary bladder and urethra

when someone has hypertension, what organ should the sonographer look at?

kidneys because they are closely related to blood pressure

kidneys

• aka renals

• located in retroperitoneum on each side of spine

• bean-shaped

• 9-12 cm (in adult)

• excretory organ

function of the kidneys

• maintain body’s chemical equilibrium

• maintain composition of blood, blood pressure, and pH balance (through excreting waste products)

which kidney is lower and shorter?

right kidney (because it is pushed down by RLL; closer to bladder)

kidneys lie between what vertebrae?

12th thoracic and 4th lumbar vertebrae

adrenal glands

• endocrine organ

• could possibly be seen with US in infants and young children

• consists of an independently functioning cortex and medulla

• supplied by suprarenal arteries

• drained by suprarenal vein

adrenal cortex

• has 3 zones that produce steroids called corticoids

  • aldosterone

  • cortisol

  • sex hormones

adrenal medulla

• secreted epinephrine and norepinephrine

  • “fight-or-flight response”

LRV and RRA locations

LRV

• anterior to AO; posterior to SMA

• runs from left kidney to IVC

RRA

• posterior to IVC (excuse me)

• runs from AO to RK

??

LRV

??

RRA

structures anterior to the RK and LK

anterior to RK

• right adrenal gland

• RLL

• Morison’s pouch

• 2nd part of duodenum

• hepatic flexure of colon

anterior to LK

• left adrenal gland

• splenic flexure of colon

• coils of jejunum

Morison’s pouch

• aka hepatorenal recess or subhepatic recess

• space between liver and RK

• patients may have ascites here

• right posterior subhepatic space located anterior to kidneys and inferior to liver where fluid may collect

anatomy of the kidneys

• composed of 2 distinct areas:

  • peripheral parenchyma (cortex and medulla)

  • central sinus

renal parenchyma

• homogeneous

• consists of cortex (outer) and medulla (inner)

renal cortex

• outer parenchyma of kidney

• contains renal corpuscle and proximal and distal convoluted tubules

renal medulla

• inner portion of renal parenchyma

• consists of 8-18 pyramids

• pyramids are triangular

  • apex is located in minor calyx

  • base is located in renal cortex

• pyramids contains the loop of Henle

• SONO: anechoic; located just at the hyperechoic/echogenic sinus

what is the loop of Henle responsible for?

filtration and reabsorption

what separates the medullary pyramids?

columns of Bertin—area between pyramids

renal pelvis/sinus

• aka renal sinus

• area in midportion of kidney that collects urine before entering the ureter

• central area of kidney that includes calyces, renal vessels, fats, nerves, and lymphatics

• composed of collecting system and renal hilum (includes the artery and vein)

• SONO: central, hyperechoic area of kidneys

collecting system

• consists of an infundibulum that has a minor and major calyces that receive urine

  • minor calyces: forms periphery of sinus

  • major calyces: receives urine from minor calyces

renal hilum (hilus)

• medial portion of sinus where artery enters and vein and ureter exits

• area in midportion of kidneys where renal vessels, ureter, and lymphatics enter and exit

ureters

• retroperitoneal structures that exit the kidneys to carry urine to the urinary bladder

• begins as expanded upper area of renal pelvis

• urine enters bladder via the ureters every several seconds or minutes

• SONO: not seen unless obstruction present

• SONO: “jets” in bladder

what process allows for urine to be transported from the kidneys to the bladder?

peristalsis

UPJ

• short for ureteropelvic junction

• near kidneys

UVJ

• short for ureterovesical junction

• near bladder

urinary bladder

• muscular retroperitoneal organ that serves as a reservoir for urine

• midline muscular elastic sac anchored to pelvis by pubovesical or puboprostatic ligaments (in females and males respectively)

• bladder wall is primarily composed of the detrusor muscle (smooth muscle)

• openings:

  • posterior, lateral openings for the ureters

  • anterior opening for the urethra

• inferior portion of bladder is the base (trigone area) and neck

  • located between the two ureteral openings and the internal urethral orifice

• SONO: bladder wall should be smooth, thin, and hyperechoic (3-6 mm); lumen should be anechoic, urine-filled

detrusor muscles _____ to expel urine

contract (needs to squeeze and expel urine)

urethra

• small, membranous canal that excretes urine from urinary bladder

  • contains internal and external sphincters

• male urethra: ~20 cm long

  • male has 3 parts: prostatic, membranous, and penile urethra

• female urethra: ~3.5 cm long

• SONO: not routinely visualized (but image shows where it would be)

indications for imaging renals

• low urine output (low UOP)

• flank pain

• blood or debris in urine

• elevated labs

• known renal disease

• HTN or diabetes

nephrectomy

surgical removal of kidney(s)

scanning techniques for imaging renals

• curvilinear probe; linear probe for peds

• pt. supine, decubitus, or oblique

• use liver/spleen as acoustic window

• have patients take in deep breaths to move diaphragm and kidneys downward

• must have 3 kidney measurements (L x H x W)

• TCG adjustments

  • compare renal cortex to liver parenchyma

• renal detail may be obscured if patient has hepatocellular disease, gallstones, rib interference, or other abnormal conditions

renal vasculature

M.S.I.A.I.

• main renal artery

• segmental renal artery

  • at hilum

• interlobar arteries

  • between/along pyramids

• arcuate arteries

  • at base of pyramids

• interlobular arteries

  • near edge of cortex

M.S.I.A.I.

what is the course of the RRV?

RRV extends from central renal sinus directly into IVC

renal physiology

• primary function is urine production and homeostasis

  • excrete waste and maintain blood volume

• filter ~1600 mL of blood per minute

• produce ~150 mL of urine daily

• nephron=functioning unit of the kidneys

  • cortical nephron (outer; closer to cortex)

  • juxtamedullary nephron (inner; closer to medulla)

urine is composed of what?

• 95% water

• 5% nitrogenous waste and inorganic salts

  • BUN (blood, urea, nitrogen)

  • Cr (creatinine)

nephron and urine production (steps)

1. filtration

• 1st step in urine formation

2. tubular reabsorption

• takes place in proximal convoluted tubule (65%) AND

• ascending and descending loop of Henle

3. tubular secretion

• urine exits distal convoluted tubule and flows through collecting ducts —> renal pyramids that lie in minor calyx —> major calyx —> renal pelvis —> ureter —> bladder —> urethra

Bowmans capsule

• site of filtration in kidneys

• contains water, salts, glucose, urea, and amino acids

glomerulus

• network of capillaries that are part of filtration process in kidneys

loop of Henle

• located in medulla

• portion of renal tubule lying between proximal and distal convoluted portion

• reabsorption of fluid, sodium, chloride occurs here and in proximal convoluted tubule

lab values associated with kidneys

• urinalysis

• urine pH

• specific gravity

• blood urea nitrogen (BUN)

• hematocrit

• hemoglobin

• protein

• creatinine clearance

• glomerular filtration rate

renal variants and anomalies

• prominent columns of Bertin

• dromedary hump

• extrarenal pelvis

• junctional parenchymal defect

• fetal lobulation

• renal agenesis

• horseshoe kidney

• ectopic kidney

• double collecting system

prominent columns of Bertin

invagination of cortex into medulla; indent of renal sinus (between pyramids)

??

prominent columns of Bertin

dromedary hump

bulge in cortex; pyramids go up with the buldge

??

dromedary hump

extrarenal pelvis

central cystic pelvis that extends outside the pelvis; best seen in TRANS

??

extrarenal pelvis

junctional parenchymal defect

echogenic triangle located anteriorly and superiorly—congenital; best seen in SAG

??

junctional parenchymal defect

fetal lobulation

lumpy kidney—not smooth

??

fetal lobulation

renal agenesis

absence of kidney

• leads to enlarged kidney and enlarged adrenal gland in peds

• sonographer should still image kidney area (“right renal fossa”) and take cine in SAG and TRANS to ensure there is no mass

??

renal agenesis

horseshoe kidney

fusion of lower poles, connected via isthmus (anterior to spine and AO)

??

horseshoe kidney

ectopic kidney

aka sacral kidney; adjacent to pelvis

??

ectopic (or sacral) kidney

double collecting system

duplex system—2 ureters and 2 renal sinuses

??

double collecting system

what method is used to determine the appropriate work-up for a cystic mass?

Bosniak classification system

cystic mass

• anechoic

• smooth, thin, well-defined

• round or oval shape

• sharpe interference between cyst and renal parenchyma

• increased posterior acoustic enhancement

describe

“cystic structure with posterior enhancement measuring 3 cm x 3 cm x 3 cm noted in LP or RK”

simple renal cyst

• MC renal mass lesion

• occur in 50% of population

• solitary or multiple

• s/s: asymptomatic—often incidental finding

solid mass

• echogenic shades of gray representing tissue (low-level internal echoes)

• ? irregular borders

• ? weak posterior borders

• poorly defined interface between mass and kidney

• poor through-transmission

describe

“solid structure measuring 3 cm x 3 cm x 3 cm noted in LP of RK. no vascularity noted within”

complex mass

• shows characteristics of both cystic and solid lesions

• may contain septations, thick walls > 1 mm, nodularity, calcifications, internal echoes from areas of necrosis, hemorrhage, or abscess/infection

** if there is septation in cyst, put color box on it, especially if its thick

describe

“complex structure measuring 3 cm x 3 cm x 3 cm noted in UP/MP LK. vascularity noted within”

complex cyst

• may contain septations, thick walls, calcifications, internal echoes, and mural nodularity

• considered malignant until proven benign, especially if septa >1 mm thick with vascular flow on color or Power Doppler

• any irregularity at the base of the cyst should be considered a malignant growth

??

complex cyst

• has septations and solid components

renal cysts associations

• von Hippel-Lindau

• tuberous sclerosis

• acquired cystic kidney disease or acquired cystic disease of dialysis

von Hippel-Lindau

• autosomal dominant genetic disorder involving many body systems

• abnormal growth of blood vessels called angiomas develop (retinal)

• SONO:

  • multiple cortical cysts

  • abdominal cysts

tuberous sclerosis

• autosomal dominant genetic disorder

• characterized by mental retardation and seizure

• SONO:

  • angiomyolipomas

  • multiple renal cysts

• differential dx: adult polycystic kidney disease (ADPKD) or angiomyolipoma

acquired cystic kidney disease or acquired cystic disease of dialysis

• found in native kidneys of patients in renal failure

• require dialysis

• increased risk of adenomas and renal carcinoma

• SONO:

  • small echogenic native kidneys

  • small cysts in cortex

autosomal recessive polycystic kidney disease (ARPKD)

• aka infantile polycystic disease

• rare disorder caused by gene located on chromosome 6

• 4 forms based on age of patient when clinical signs present:

  • Perinatal, neonatal, infantile, and juvenile

• dilation of renal collecting tubules → renal failure and later liver involvement

what is another name for autosomal recessive polycystic kidney disease (ARPKD)?

infantile polycystic disease

SONO: autosomal recessive polycystic kidney disease (ARPKD)

• enlarged echogenic (cortex and medulla) kidneys with microscopic or small cysts

• lack corticomedullary differentiation (can’t tell difference between cortex and medulla)

autosomal dominant polycystic kidney disease (ADPKD)

• ADPKD1 is MC and found on the short arm of 16th chromosome (affects kidney more severely)

• severity varies depending upon the genotype

• manifest around 40-50 y/o

• s/s: pain; HTN; hematuria; headache; UTI; palpable mass; renal insufficiency

• family history and tissue sampling is required for dx confirmation

• high incidence of urolithiasis and RCC in dialysis patients

what is another name for autosomal dominant polycystic kidney disease (ADPKD)?

adult polycystic renal disease

SONO (neonates vs. adults): autosomal recessive polycystic kidney disease (ADPKD)

neonates:

• enlarged kidneys

adults:

• enlarged kidneys with asymmetrical cysts in cortex and medulla

• loss of reniform shape (kidney shape)

?? describe

autosomal dominant polycystic kidney

• “multiple cystic structures noted throughout RK. ?polycystic kidney dz”

??

autosomal dominant polycystic kidney (ADPKD)

multicystic dysplastic kidney (MCDK)

• MC form of cystic disease in neonates

• unilateral non-functioning kidney

• bilateral MCDK is incompatible with life

• s/s: hematuria; infection; flank pain

• increased risk of malignancy of kidney is not removed

SONO (neonates/children vs. adults): multicystic dysplastic kidney (MCDK)

neonates/children:

• kidneys are multicystic and enlarged

• renal artery atresia

adults:

• atrophic kidneys

• calcified

• echogenic

??

multicystic dysplastic kidney (MCDK)

medullary sponge kidney (MSK)

• developmental anomaly occurring in pyramids —> stasis of urine and stone formation

  • cystic/fusiform dilation of distal collecting ducts —> stasis and stone

• s/s: asymptomatic; hematuria; infection; renal stones

• may be associated with Beckwith-Wiedemann syndrome, polycystic kidney disease, Caroli’s disease (Type 5) and congenital hepatic fibrosis

medullary cystic kidney disease (MCKD)

• MCKDs include: medullary nephrocalcinosis and cortical nephrocalcinosis

• both are inherited disorders that eventually lead to ESRD

SONO: medullary cystic kidney disease (MCKD)

hyperechoic calyces with or without stones

??

medullary cystic kidney disease

• calcium deposits in calyces

??

medullary nephrocalcinosis (medullary cystic kidney disease)

• calcium deposits in medulla (heart-shaped ♥)

??

cortical nephrocalcinosis (medullary cystic kidney disease)

• calcium deposits in cortex

renal cell carcinoma (RCC)

• MC renal malignant

• higher incidence in men ~60-70 years old

• s/s: hematuria, flank pain, and palpable mass

• associated with von Hippel Lindau disease, acquired cystic disease in dialysis patients, and tuberous sclerosis

• metastasis to lungs, mediastinum, liver, bone, ipsilateral kidney

what are other names for RCC?

hypernephroma and Grawitz Tumor

SONO: renal cell carcinoma (RCC)

• isoechoic or hyperechoic

• solid or cystic

• intratumoral calcification

• hypoechoic rim (represents vascular pseudocapsule on color Doppler)

• MC vascular patterns is “basket sign” and/or “vessels within tumor”

• ?invasion of the renal vein and IVC

RCC can invade what vessels?

renal vein and IVC

?? describe

RCC

• “isoechoic solid circumscribed structure noted in MP/LP of RK measuring 3 cm x 3 cm x 3 cm. difficult to determine border”