Urinary System Flashcards
Organs of the urinary system
kidneys (renals), ureters, bladder
Renal function
- produces urine & erythropoietin
- detoxifies blood
- regulates serum electrolytes
- regulates acid-base balance
- fluid regulation
-endocrine function - balances calcium levels
What should not be in urine?
- blood (signifies leak in vessel)
- protein (sign of kidney damage)
What does erythropoietin do?
- part of endocrine system (hormones)
- regulates the amount of RBC’s
What structures in the body make RBC’s?
bone marrow & spleen
How is blood detoxified in the renals?
- kidneys send blood through tubes to balance blood contents
- BP issues if not working properly
What happens if calcium levels are not balanced?
thyroid, kidney, or gut issues (calcium is absorbed in the gut)
Are kindney stones similar to gallstones?
yes
Kidney size
9-12 cm in length (up to 14 cm)
Kidney shape
oblong & less wide, bows out
Kidney location
- paired structures located in the flank area
- posterior, superior retroperitoneum (within this space)
- lateral to spine
Kidney borders
convexx lateral border & concave medial border
Where is the hilum?
concave medial border
What enters and exits at the hilum?
artery enters, vein and ureter exits
Renal position
- superior pole is tipped posteriorly & medially
- superior kidney is more towards spine in coronal
- superior kidney is pointed more posterior in sagittal
Scanning the kidneys
- tilt diagonally
- usually intercostal
Appearance of the 2 regions of parenchyma
- outer = hypoechoic
Renal cortex
- outermost functioning unit
- doesn’t completely make circle around medial border
Renal medulla
middle functioning unit
Renal sinus
- inner = echogenic
- urine collecting system
- blood vessels coming in & out of liver
- fat
What does fat in the renals do?
- makes sinus echogenic
- within hilum & used as a cushion so collecting system can expand under pressure w/o immediate pain
How should you label kidneys in sagittal?
long Rt or long Lt
Renal cortex structures
- covered by fibrous capsule
- nephrons: glomerulus, tubules
- capillary bed: juxtaglomerular apparatus
- group: Bowman’s capsule
- columns of Bertin
Renal cortex function
- nephrons under capsule filter blood & produce urine
Where does filtration happen?
glomerulus & tubules of renal cortex
What occurs in the tubules of the renal cortex?
absorption & excretion
Capillary bed
capillaries = smallest piece that blood goes through (1 cell layer thick)
Juxtaglomerular apparatus
- w/in capillary bed
- BP regulation
- balances fluid
- tumor would make BP out of control
Bowman’s capsule
clusters the nephrons
Columns of Bertin
- bands of cortex towards the sinus
- btwn. the pyramids
Renal medulla structures
- inner surface of parenchyma
- medullary pyramids
- apex to the center of kidney (papilla)
Inner surface of the parenchyma
loops of Henle
Medullary pyramids
- multiple inverted conical structures separated by Columns of Bertin
- where urine is deposited, can be anechoic
Medullary pyramid size
- sometimes one column can be bigger
- determine if it is a mass or just a big piece of cortex
Apex to the center of kidney (papilla)
- urine collection & transport into calyceal system
- papilla die = echogenic (can be a problem if prolonged)
What could be occurring if the medullary pyramids become echogenic?
papillary necrosis
Renal sinus structures
- collecting (collecting) system: minor & major calyces
- renal pelvis: hilum, vasculature, fat
Renal sinus functions
- renal pelvis creates funnel to ureter
- room for expansion
responsible for echogenic appearance
How does fat in the renal pelvis appear on a scan?
- calyces are not seen b/c fat compresses them
- makes them echogenic
Gerota’s fascia
- surrounds the capsule & perinephric fat around cortex
Is blood in the fascia normal or abnormal?
abnormal
Supporting structures of the kidney
- fibrous renal capsule
- perirenal/perinephric fat
- gerota’s fascia
- pararenal/paranephric fat
Which kidney is easier to visualize on a scan?
right kidney b/c outer cortex is hypoechoic to the echogenic renal sinus
Sonographic appearance of kidneys
- surrounds renal sinus except at the hilum
- medulla is identified easiest by anechoic pyramids
- evenly spaced around echogenic renal sinus
What is the most important measurement of the kidney?
long axis measurement
Long axis (Sagittal or Coronal) scan of kidney
- take measurement
- cortical thickness
- lateral to medial sweep
Difference between sagittal vs. coronal scan of kidney
- you will not see the hilum in sagittal
- you will see broken hilum in coronal
What is often not found on newborn kidneys?
fat
Transverse scan of kidney
- poles (lobes) of the kidney: superior, mid-hilum, inferior
- scan both superiorly & inferiorly
Appearance of each pole of the kidney on a scan
- superior: should not see sinus
- mid-hilum: medial border of cortex should be broken
- inferior: cortex all the way around
Types of cortical thickness
- normal
- thinning
Average adult kidney length
9-12cm
Kidney size differences
- if one kidney is 1.5 - 2cm smaller, could be kidney disease
- acute = sudden, chronic = develops overtime
Ureters
- renal pelvis becomes single ureter (medial to hilum)
- one on each kidney
- 1 way valve so urine doesn’t flow back into the body from the bladder
Where do the ureters cross?
comes from either side of the spine & crosses anterior to the iliac vessels
What happens if the ureters do not cross correctly?
if they do not cross anteriorly, they can get compressed
Where do the ureters enter?
- enters the posterior/inferior area of bladder
- looks like a bump/mound of tissue
When would we see the ureters?
should not see ureters unless they are abnormal (dilated)
Bladder function
- storage tank in ML of pelvis
- smooth muscle wall permits distention (like a water balloon)
Bladder structures
- smooth muscle wall (4 layers inner to outer)
- detrusor muscle
- apex
- trigone area
- urachal ligament
4 layers of smooth muscle in the bladder
- mucosa, submucosa, muscularis, serosa
What could be occurring if one area of the bladder is thicker than another?
infection or tumor development
What scan plane can you see the full bladder in?
sagittal (superior to inferior)
Which direction does the bladder expand?
superiorly
Trigone area of the bladder
- internal/external sphincters
- inferior/posterior
Urachal ligament
- ligament at the top of the bladder
- where our bladder developed in utero
Bladder appearance on a scan
- anechoic contents w/ echogenic wall
- ureteral jets identified at the trigone area
- urethra not seen unless voiding
What should we look for after seeing any hydronephrosis?
- we need to see ureters draining into the bladder (ureteral jets)
- looks like volcanoes
Why do we need to look at catheters in a scan?
catheters run the risk of infection & bleeding
Renal vasculature
- main renal artery (Rt & Lt)
- segmental arteries
- interlobar
- arcuate
- interlobular
- ureteral
Main renal artery
- right & left
- comes directly from aorta
Segmental arteries
branches to the ‘poles’ of the kidney
Interlobar vasculature
along the side walls of the pyramids
Arcuate vasculature
along the base of the pyramids
Interlobular vasculature
within the cortex
Ureteral vasculature
renal/gonadal/vesical arteries
Structures of the kidney lobes
small lobules created by nephrons
What does color show us on a scan of the kidney?
- shows the kidney is getting perfusion (blood is going into it)
- blue = veins (away)
- red = arteries (towards)
Power doppler vs. color doppler
- power doppler shows smaller vessels than color doppler
What is micro-profusion?
power doppler that is more sensitive
Adjacent anatomy of the right kidney
- liver: ant/sup
- adrenal gland: sup/med
- duodenum: med
- GB: ant/med
- C loop: upper medial edge
- colon (hep flexure): ant/lat (can get in the way ant)
- Morison’s Pouch (btwn. kidney, liver, GB)
Morison’s Pouch
- btwn. kidney, liver, GB
- most gravity dependent area in upper abdomen
If fluid is the upper abdomen, where will it typically end up?
Morison’s Pouch
Adjacent anatomy of the left kidney
- stomach: ant/med
- spleen: sup/ant
- adrenal gland: sup/med
- pancreas (tail): med
- colon (spl flexure): ant/lat (bends at spleen, can get in the way)
Agenesis
- anatomical renal variant
- 1 or both kidneys did not develop
- single kidney might enlarge since it is doing all the work
Supernumery
- anatomical renal variant
- more than 2 kidneys
Horseshoe kidney
- anatomical renal variant
- M/C renal anomaly
- kidneys on opposite side connected by isthmus
- usually fusion of lower poles occurs w/ ureters passing ant
- arterial & venous systems may be complex
What to do if you suspect a horseshoe kidney
- look to see of poles disappear medially
- look for isthmus ML, ant to AO & post to IMA
Pelvic (ectopic) kidney
- anatomical renal variant
- crossed/fused kidney
Dromedary hump
- not an anatomical renal variant, just unusual shape
- always on Lt side
- spleen compresses it
- looks like a triangle
- “bulge of cortical tissue on lateral surface of a kidney”
- isoechoic to renal cortex
- often see when liver or spleen is pressing against renal tissue
Hypertrophied column of Bertin
- prominent indentation of renal cortex w/in medulla
- usually at upper/mid kidney
- often difficult to distinguish from mass
- btwn. the pyramids
- blends w/cortical tissue
Duplex collecting system
- can cause ureter to dilate
- complete or incomplete
Complete duplex collecting system
- 2 separate collecting systems each w/ ureter leading to bladder
- inf pole ureter & sup pole ureter
Inf pole ureter
- empties into bladder more sup/lat than normal location
- increases chance of pre-vesicoureteral reflux
Sup pole ureter
empties into bladder more med/dist than normal location
Imaging complete duplex collecting system
show complete separation, all of hilum, upper/superior, upper/superior mid, mid, lower/inferior mid, lower/inferior
Incomplete duplex collecting system
- partial duplication
- most common congenital anomaly in neonatal
- 2 collecting systems
- 2 ureters that connect a single ureter that empties into bladder
- inferior - relux
- superior - obstruction
Extrarenal pelvis
- outside cystic bulge at renal hilum
- may be partially or completely beyond renal sinus tissue
- urine may drain slower, creates scum
2 types of Agenesis
- bilateral = incompatible w/ life
- unilateral = compensatory hypertrophy
Hypoplasia
- bilateral or unilateral
- appearance of normal small kidney = too few nephrons
- <5 calyces
Ectopia
- absence of kidney in expected renal fossa
- can cause complication: nephrolithiasis
Ectopia location
- located in pelvis (bilateral is rare)
- almost always malrotated
- kidney is contralateral to ureteral insertion
Cross-fused ectopia
- kidneys on same side & fused
- see if tissue moves together when scanning
Junctional parenchymal defect (Interranuncular notch)
- triangular
- echogenic area ant/sup
- deep diagonal groove
- incomplete fusion of upper & lower poles during embryonic development
Fetal lobulation
- infolding/indenting of cortical contour
- slightly lobulated appearance
When does fetal lobulation occur?
- first year of life
- may persist or return in later years
Renal ptosis
- unusual mobile kidney
- descends from normal position towards pelvis
- poor support structures
Renal sinus of lipomatosis
- excess of fat/fibrous tissue w/in the sinus
- sinus may increase in size/echogenicity
- appearance of decreased cortical thickness
What should you do if any anechoic structures are seen within the central, echogenic sinus?
- evaluate closely
- determine if it’s vasculature or dilated calyces
What should the renal contour look like?
- should be smooth or at least uniformly lobulated
- look for bumps
Describe cortical thickness
- slightly thicker on the inferior/medial border
- > 1cm thickness
What does color show?
- shows organized flow
- proves something is not a mass
