Urinary Tract Flashcards
Where are the paired kidneys and ureters located?
Retroperitoneal lying against the deep muscles of the back
How are the structures located in the hilum of the kidney?
Vein exits anteriorly
Artery enters between vein and ureter
Ureter exits posteriorly
Describe the echogenicity of the kidney structures.
Renal cortex - isoechoic or hypoechoic
Medullary pyramids - anechoic
Renal sinus - hyperechoic
What is the renal cortex?
Outer renal parenchyma from renal sinus to renal capsule (1 cm)
What is the renal medulla?
Inner hyperechoic portion of kidney which contains fat, calyces, renal pelvis, CT, renal vessels, and lymphatics
What are the medullary pyramids?
Anechoic, equally spaced triangles of collecting tubules between cortex and renal sinus
What is the renal pelvis?
Funnel-shaped transition from the major calyces to the ureter
What is the renal hilum?
Medial opening for entry/exit of artery, vein and ureter
What are the major calyces?
3 extensions for the renal pelvis
What are the minor calyces?
Extensions of the major calyces that collects urine from the medullary pyramids
What are the renal papilla?
Apex of medullar pyramids
What is Gerota’s fascia?
Fibrous sheath enclosing kidney and adrenal glands (perirenal space)
What is a nephron?
Functional unit of kidney - renal corpuscle, proximal convoluting tubule, desc and asc limbs of Henle’s loop, distal convoluted tubule, and collecting tubules
What is the renal corpuscle (Malpighian body)
Glomerulus and glomerular capsule (Bowman’s capsule)
Describe blood flow from aorta to kidney.
Aorta > Main renal artery > 5 Segmental arteries > Interlobar arteries > Arcuate arteries > Interlobular arteries
What are some complications associated with congenital abnormalities?
Obstruction and stasis
Impaired renal function
Infection
Calculus formation
What is an ectopic kidney?
Kidney that failed to “ascend” into the abdomen and remains in the pelvis
What is the most common fusion anomaly?
Horseshoe kidney - lower poles typically connect across midline anterior to the aorta
Where is the horseshoe kidney located?
Lower in the abdomen because ascent is prevented by the IMA
What is the difference between a complete and incomplete duplex kidney?
2 ureters v 1 ureter
What is a duplex kidney?
Duplication of the collecting system
What is a frequent complication of the ectopic ureter in a duplex kidney?
It inserts in an ectopic location on the bladder and develops a ureterocele - a prolapse of the distal ureter into the bladder
What is a Column of Bertin?
Septal cortex - a normal variation of prominent renal cortical parenchyma located between 2 medullary pyramids
What is bilateral renal agenesis commonly associated with?
Oligohydramnios and pulmonary hypoplasia
Incompatible with life
What is unilateral renal agenesis frequently associated with?
Bicornuate uterus in females
Seminal vesicle agenesis in males
What is an extrarenal pelvis?
A renal pelvis that lies outside the renal sinus sonographically appearing as a cystic collection medial to the renal hilum
What is a common cause of urinary obstruction in the male neonatal patient?
Posterior uretheral valve
What are sonographic findings of a posterior urethral valve?
Large bladder
Hydroureter
Hydronephrosis
Urinoma
What is the incidence of renal cysts?
50% of people over age 50
What are most renal cysts?
Cortical cysts that originate from obstructed uriniferous tubules
What are the different types of renal cysts?
Cortical cysts
Pylogenic cysts
Parapelvic cysts
Peripelvic cysts
Where are renal cysts located?
Cortical and parenchymal cysts - periphery
Peripelvic cysts - center (renal sinus)
What can mimic a simple cyst and is associated with a hx of renal biopsy or trauma?
Renal pseudoaneurysm
How can an abscess be differentiated with a hemorrhagic cyst?
Percutaneous aspiration
What are characteristics of atypical renal cysts?
Multiple or thick septations
Thick calcifications
Mural nodule/Solid component
What is autosomal dominant polycystic kidney disease?
Bilateral renal enlargement d/t development of numerous cysts of varying sizes
What occurs in advanced stages of PCKD?
Renal failure and HTN
What are commonly associated with PCKD?
Arterial aneurysms - particularly cerebral artery (Berry) aneurysms of the circle of Willis
What is autosomal recessive PCKD?
Multiple small cysts that result from cystic dilation of the collecting tubules secondary to hyperplasia of interstitial portions of the ducts
What is autosomal recessive PCKD associated with?
Renal dysfunction
Pulmonary hypoplasia
Periportal fibrosis
Portal HTN
What is Potter Syndrome?
Appearance of a neonate as a direct result of oligohydramnios and compression while in utero
What are causes of oligohydramnios?
B/L renal agenesis AR PCKD AD PCKD Multicystic renal dysplasia Obstructive uropathy Early ROM
What is the most common cause of an abdominal mass in newborns?
Multicystic dysplastic kidney
What is multicystic dysplastic kidney?
Renal dysplasia from multiple noncommunicating cysts with the absence of renal parenchyma from atresia of the UPJ during fetal development
What are associated urinary malformations of MDK?
Contralateral UPJ obstruction Contralateral renal agenesis or hypoplasia Crossed fused renal ectopia Horseshoe kidney Patent urachus Ureterocele Vesiocureteral reflux
What causes congenital UPJ obstruction?
Ureteral hypoplasia
High insertion of ureter into the renal pelvis
Compression by segmental artery
What is acquired cystic disease?
Development of multiple cysts in chronically failed kidney during long-term HD
What is a medullary sponge kidney?
Congenital dysplastic cystic dilatation of the medullary pyramids due to tubular ectasia or dysplasia
How does medullary sponge kidney appear on US?
Hyperechoic medullary pyramids - from Ca++ deposits
What is Von Hippel-Lindau disease?
Inherited disease that presents in 2nd-3rd decade of life with serious visual impairment from retinal and CNS hemangioblastomas
What is an angiomyolipoma?
Hyperechoic benign renal tumor
What is tuberous sclerosis?
Multi-system genetic disease that presents as seizures, MR and facial angiofibromas with increased incidence of renal cysts and angiomyolipomas
What is renal cell carcinoma?
Most common solid renal mass in adult - typically unilateral encapsulated mass
How does renal cell CA appear on US?
Hypoechoic relative to normal adjacent renal parenchyma
How does renal cell CA present?
Hematuria (most common)
Flank pain
Palpable mass
Where is the most common site of distant mets for renal cell CA?
Lung
How do renal mets appear on US?
Hypoechoic masses or
Diffusely enlarged inhomogeneous kidney
What is a Wilm’s tumor?
Nephroblastoma - most common childhood renal tumor
How do patient’s present with a Wilm’s tumor?
Age 3-5 Large asymptomatic flank mass HTN Fever Hematuria
What must a Wilm’s tumor be differentiated from?
Adrenal neuroblastoma
Wilm’s tumors destroy the renal contour
How does acute pyelonephritis appear on US?
Renal enlargement
Hypoechoic parenchyma
Absence of sinus echoes
What is lobar nephronia?
Acute focal bacterial nephritis or focal acute pyelonephritis
What is emphysematous pyelonephritis?
Bacterial infxn associated with renal ischemia
Which populations are most commonly affected by emphysematous pyelonephritis?
Diabetics
Immunosuppressed patients
Pts with urinary tract obstructions
What is chronic pyelonephritis?
Renal injury induced by recurrent renal infection due to anatomic anomalies, obstruction, ureteral reflux
What is xanthogranulomatous pyelonephritis?
Chronic pyelonephritis resulting from chronic infxns due to long term obstruction
What are associated findings of xanthogranulomatous pyelonephritis?
Renal enlargement Parenchymal abscesses Staghorn calculus Papillary necrosis Hydronephrosis Pyonephrosis Loss of cortical-medullary boundary Cortical thinning
What is pyonephrosis?
Purulent material in the collection system of the kidney associated with an infxn secondary to renal obstruction
What is a mycetoma?
Fungal ball - candidiasis most common
What are hyperechoic renal masses?
Mycetoma Angiomyolipoma Blood clots Pyogenic debris Sloughed papilla Renal stones
How is US used to dx cause in AKI?
Hydronephrosis
Abnormal resistive index
What is renal vein thrombosis associated with?
Extrinsic compression Nephrotic syndrome Renal tumors Renal transplants Trauma
How does renal vein thrombosis appear on US?
Dilated thrombosed renal vein
Absent intrarenal venous flow
Enlarged hypoechoic kidney
High-resistance renal artery waveform
What occurs in renal artery thrombosis?
Sudden cause of prerenal failure
Acute flank pain
Hematuria
Sudden rise in BP
How does renal artery thrombosis appear on US?
Focal hypoechoic areas of infarct
Absence of intrarenal arterial flow
Renal enlargement
What is acute tubular necrosis?
Most common cause of AKI from prolonged ischemia or nephrotoxins causing damage to the tubular epithelium of the nephron leading to acute renal failure
What is acute glomerulonephritis?
Inflammatory response resulting in glomerular damage caused be infectious (Strep) and noninfectious causes
How does acute glomerulonephritis appear on US?
Renal enlargement
Increased resistive index
What is evaluated when diagnosing obstructive nephropathy?
Intrarenal vascularity
Threshold resistive index (RI) > 0.7 - obstructive hydronephrosis
What are the most common causes of newborn/prenatal hydronephrosis?
Vesicoureteral reflux
Non-obstructive hydronephrosis
UPJ obstruction
What is nephrocalcinosis?
Disorders of Ca++ metabolism resulting in the formation of calcium renal stones and deposition of calcium int he renal parenchyma
What is Twinkle Sign?
Color Doppler artifact that appears as a rapidly alternating mixture of red and blue Doppler signals distal to a strongly reflective surface, like a stone.
What are different causes of nephrocalcinosis?
Medullary - Primary hyperparathyroidism, RTA, Medullary sponge kidney
Cortical - Chronic GN, Renal cortical necrosis, Transplant kidney
What is papillary necrosis?
Ischemia of the medullary pyramids
What is papillary necrosis associated with?
DM
Urinary tract obstruction
Analgesic abuse
Sickle cell disease
What does papillary necrosis look like on US?
Echogenic material in collecting system
Triangular cystic collections
Bright echoes
What is renal sinus lipomatosis?
Increase renal sinus fat that replaces normal renal parenchyma
How does renal sinus lipomatosis appear on US?
Increase in central sinus echo complex with cortical thinning
How is the urinary bladder connected to the umbilicus?
Median umbilical ligament (urachus)
What is a normal bladder wall thickness?
<3 mm when distended
What is a bladder diverticula?
Herniations of the bladder mucosa through the bladder wall musculature
What is a urachal cyst?
Cystic dilatation of fetal urachus
How do the ureters travel in the body?
Exit kidney posterior to renal artery and vein, anterior to psoas, anterior to common iliac vessels to insert upon the trigone of bladder
What is a ureterocele?
Cyst-like enlargement of the lower end of the ureter that projects into the bladder lumen
What is a transitional cell carcinoma?
Most common bladder neoplasm
What type of cells line the urinary tract?
Transitional cells
What is the most common clinical presentation of transitional cell carcinoma?
Hematuria
What is resistive index commonly used for?
Evaluate renal transplant rejection
Assess suspected hydronephrosis
Evaluate medical renal disease
What does renal dysfunction result in?
Loss of diastolic flow thus increased renal arterial resistance
How is RI measured?
RI = (peak systolic freq - end diastolic freq)/ peak systolic freq
What are sxs of renal artery stenosis?
Sudden onset of HTN
Uncontrollable HTN
What are renal artery stenosis diagnostic criteria?
Direct eval (renal artery velocities) = renal artery/aorta ratio (RAR) >3.5 Indirect eval (intrarenal waveform eval) - Parvus Tardus, Absent early systolic peak
Which kidney is typically harvested and why?
Left kidney for longer renal vein
How is US used in renal transplant?
Assess immediate surgical complications
Location for renal biopsy
Vascular status in acute rejection
What are post-transplant complications?
Fluid collections
Renal artery kinking or thrombosis
Renal vein thrombosis
What are sonographic findings of acute transplant rejection?
Renal enlargement (increased length)
Decreased kidney echogenicity
Loss of cortical medullary boundary
Increasing flow resistance (RI)
What is crossed fused renal ectopia?
Developing kidneys fuse in pelvis and one kidney ascends to its normal position carrying the other one with it across the midline
What is a discoid or pancake kidney?
Fused pelvic kidney
What is a Dromedary hump?
Common variant of cortical thickening on lateral aspect of left kidney
What is a junctional parenchymal defect?
Triangular hyperechoic area on anterior aspect of upper pole of the right kidney
What is fetal lobulation?
Partial fusion of the renunculi