Renal Sonography

URINARY SYSTEM -SONOGRAPHY

MDU

EMBRYOLOGY

• Discuss the embryology
• Development of the Kidneys and Ureter
• Development of the Bladder

Development of the Urethra

PHYSIOLOGY

• The nephron is the basic functional unit of the kidney.
• Each kidney contains over one million nephrons.

Functions of the Urinary System

• Produces urine and erythropoietin.
• Influences blood pressure, blood volume, and intake or excretion of salt and water through the renin–angiotensin system.
• Regulates serum electrolytes.
• Regulates acid–base balance.

RENAL ANATOMY(REFERS TO PREVIOUS LECTURES)

Renal Vasculature(REFERS TO PREVIOUS LECTURES)

Pause

Renal Anatomical Variants

Refers to previous lectures

Hypertrophied column of Bertin

Congenital Anomalies

1.Agenesis

• Absence of the kidney(s)
• Unilateral or bilateral
• Clinical findings
• Asymptomatic when unilateral
• Fatal when bilateral

Associated with genital anomalies

SONOGRAPHIC FINDINGS

• Empty renal fossa(e)
• Large, contralateral kidney
• Ddx
• Pelvic kidney
• Surgical removal

Crossed fused ectopia

Cake kidney

• Variant of a horseshoe kidney
• Found in the pelvis
• Clinical findings
• Asymptomatic

Pelvic mass

SONOGRAPHIC FINDINGS

• Fusion of entire medial aspect of both kidneys
• Anterior rotation of the renal pelvis
• Ddx
• Crossed fused ectopia

Renal mass

Crossed fused ectopia

• Both kidneys are fused in the same quadrant
• Two separate collecting systems
• Two normally located adrenal glands
• Clinical findings
• Asymptomatic

Abdominal mass

SONOGRAPHIC FINDINGS

• One single, large kidney
• Irregular contour
• Inferior pole is directed medially
• Ddx
• Renal mass
• Cake kidney

Sigmoid kidney

Duplication

• Two distinct collecting systems
• May involve kidney, ureter, and/or renal pelvis
• May be partial or complete
• Clinical findings
• Asymptomatic

Flank pain

SONOGRAPHIC FINDINGS

• Increase in renal length
• Two distinct collecting systems
• The superior system is most likely to obstruct
• Ddx
• Hypertrophied column of Bertin

Renal mass

Horseshoe kidney

• Fusion of the kidneys usually at the inferior poles
• Connected by an isthmus of functioning parenchyma or nonfunctioning fibrotic tissue
• Anterior rotation of the renal pelves and ureters
• Separate collecting systems
• Most common form of renal fusion
• Clinical findings
• Asymptomatic

Pulsatile abdominal mass

SONOGRAPHIC FINDINGS

Bilateral low-lying medially placed kidneys with partial or complete fusion of the inferior poles “Dipping effect” of both inferior poles Isthmus of tissue demonstrated anterior to the abdominal aorta Isthmus echo texture is similar to the renal cortex Ddx

• Renal mass
• Lymphadenopathy
• Bowel

Retroperitoneal tumor

Pelvic kidney

• Failure to ascend with development
• Associated with a short ureter
• Renal artery and vein are located more inferior
• Renal vein drains directly into the inferior vena cava (IVC)
• Asymptomatic

Pelvic pain

SONOGRAPHIC FINDINGS

• Elongated core of echogenic tissue surrounded by less echogenic parenchyma
• Located in the lower abdomen or pelvis
• Empty ipsilateral renal fossa
• Lies in an oblique plane
• Ddx
• Bowel

Pelvic mass

Renal ptosis

• Unusual mobile kidney that descends from the normal position toward the pelvis
• Poor support structures
• Clinical findings

Asymptomatic

Sono Abnormal mobility of a kidney

• Ddx
• Pelvic kidney
• Horseshoe kidney

note

Nephroptosis is a rare condition where a person's kidney drops down into the pelvis when they stand up.

Sigmoid kidney

• Variant of the horseshoe kidney
• clinical findings
• Asymptomatic

Abdominal mass

SONOGRAPHIC FINDINGS

• Superior pole of one kidney is fused with the inferior pole of the contralateral kidney
• S-shaped
• Ddx
• Bowel

Abdominal mass

Thoracic kidney

• migrates into the chest through a herniation in the diaphragm
• Rare finding
• Clinical findings

Chest mass

SONOGRAPHIC FINDINGS

• Elongated core of echogenic tissue surrounded by less echogenic parenchyma
• Located in the chest
• Not easily demonstrated on ultrasound
• Ddx

Chest mass

Hypoplasia

Ureteropelvic Junction Obstruction

Congenital Megacalyces

Congenital Megaureter

Retrocaval Ureter

Circumcaval ureter, also known as retrocaval ureter, is a term used to describe an abnormal course of a ureter that encircles the inferior vena cava.

SIZE

• Adult
• 9.0 to 12.0 cm in length.
• 4.0 to 5.0 cm in width.
• 2.5 to 3.0 cm in height.
• Minimum of 1 cm in cortical thickness.

Child

• 7.0 to 8.0 cm in length.

Formula(expected size)

Infant

• 5.0 to 6.0 cm in length.

Formula (expected size)

Normal Sonographic Appearance—Adult Kidney

Normal Sonographic- Pediatric Kidney

TECHNIQUE

Examination Technique and Imaging Optimization

• Use the highest-frequency abdominal transducer possible to obtain optimal resolution for penetration depth.
• Place gain settings to display the normal adult renal cortex as moderate or low-level echogenicity and the renal sinus as the most echogenic with adjustments to reduce echoes within the vessels.
• Position the focal zone(s) at or below the region of interest.
• Sufficient imaging depth to visualize structures posterior to the region of interest.
• Harmonic imaging and decreasing the compression (dynamic range) can be used to reduce artifactual echoes within anechoic structures and improve prominence of posterior acoustic shadowing.

• Spatial compounding can be used to improve visualization of structures posterior to a highly attenuating structure.

• Evaluation and documentation of the superior, inferior, medial, and lateral aspects of each kidney in the coronal or sagittal plane.
• Evaluation and documentation of the superior pole, renal hilum, and inferior pole of each kidney in the transverse plane.
• Measurements of maximum length, thickness, and width of each kidney.
• Measurement of the cortical thickness of each kidney.
• Evaluation and documentation of the bladder wall.

Prevoid and postvoid bladder volumes may be included.

• Kidneys are best evaluated with an empty urinary bladder.
• Documentation and measurement of any abnormality in two scanning planes with and without color Doppler should be included.

Cystic Pathology of the Kidneys

Simple cyst

• Cause
• Acquired condition
• Found in 50% of patients over the age of 55
• Clinical findings

Asymptomatic

Sono-findings

• Anechoic mass
• Hyperechoic thin walls
• Smooth margins
• Posterior acoustic enhancement
• ddx
• Liver cyst

Adrenal cyst

Parapelvic cyst

• Cause
• Acquired condition originating from the renal parenchyma
• clinical findings
• Asymptomatic
• Hypertension

Hematuria

Parapelvic cysts are usually solitary, originating from renal parenchyma and protruding into the sinus.

Sono-findings

• Anechoic mass located in the renal hilum
• Does not communicate with the collecting system
• Hyperechoic thin walls
• Smooth margins
• Posterior acoustic enhancement
• Ddx
• Hydronephrosis
• Renal vein
• Extrarenal pelvis

Renal artery aneurysm

Peripelvic cyst

• Cause
• Acquired condition that may develop from the lymphatic system or an obstruction
• Clinical findings

Asymptomatic

Sono-findings

• Anechoic mass located near or around the renal pelvis
• Hyperechoic thin walls
• Smooth margins
• Posterior acoustic enhancement ddx
• Prominent renal pyramid

Localized hydronephrosis

Adult polycystic kidney disease

• Cause
• Inherited disorder
• Normal renal parenchyma is replaced with cysts
• Increased incidence of renal calculi and infection
• Clinical findings
• Asymptomatic
• Palpable abdominal mass
• Hypertension
• Hematuria
• Colicky pain
• Elevated blood urea nitrogen (BUN) and creatinine

Renal failure

Sono-findings

• Bilateral disease
• Multiple cysts
• Irregular margins
• Normal renal parenchyma may not be visualized
• Associated cysts in liver, pancreas, and spleen
• Ddx
• Multiple simple cysts

Hydronephrosis

Multicystic dysplasia

• Cause
• Affects the left kidney more frequently
• Noninherited disorder
• Urinary obstruction in early embryology
• Male prevalence (2:1)
• Infants of diabetic mothers
• Clinical findings
• Asymptomatic
• Palpable abdominal mass
• Flank pain

Hypertension

Sono findings

• Unilateral disease
• Numerous cysts of variable shape and size
• Associated with ureteropelvic junction obstruction and malrotation

• Ddx

Hydronephrosis

Inflammatory Condition

Renal abscess

• Cause
• Infection
• Clinical findings
• Flank pain
• Fever or chills

Leukocytosis

Sono findings

• Hypoechoic or complex mass
• Thick irregular wall margins
• Shadowing associated with gas formation
• Ddx
• Neoplasm
• Focal pyelonephritis
• Complicated cyst

Resolving hematoma

Acute tubular necrosis (ATN)

• Cause
• Toxic drug exposure
• Hypotension
• Trauma
• Surgery of the heart or aorta
• Jaundice
• Sepsis
• Asymptomatic
• Renal failure

Oliguria

Sono findings

• Bilateral enlarged kidneys
• Hyperechoic renal pyramids
• Normal renal cortex
• Ddx
• Renal sinus lipomatosis
• Chronic pyelonephritis
• Renal failure

Nephrocalcinosis

Chronic renal failure

• Cause
• Glomerulonephritis
• Hypertension
• Vascular disease
• Diabetes mellitus
• Chronic hydronephrosis
• Clinical findings
• Elevated BUN and creatinine
• Proteinuria
• Polyuria
• Headaches
• Fatigue
• Weakness

Anemia

Sono findings

• Renal atrophy
• Hyperechoic parenchyma
• Thin renal cortex
• Difficult to distinguish the kidney from surrounding structures
• Ddx
• Renal sinus lipomatosis

Hypoplastic kidney

Glomerulonephritis

• Cause
• Immune diseases
• Infection
• Strep throat
• Lupus
• Chronic hepatitis C
• Vasculitis
• Clinical findings
• Asymptomatic
• Proteinuria
• Oliguria
• Hypertension
• Hematuria
• Fatigue

Edema

Sono findings

• Hyperechoic renal cortex
• Enlarged kidney(s)
• Ddx

Renal sinus lipomatosis

Pyelonephritis

• Cause
• Bacteria ascends from the bladder
• Clinical findings
• Flank pain
• Fever or chills
• Dysuria
• Pyuria

Leukocytosis

Sono findings

• Generalized or focal swelling of the kidney(s)
• Well-defined renal pyramids
• Loss of corticomedullary definition
• Ddx
• Renal abscess

Neoplasm

Pyonephrosis

Pyonephrosis implies purulent material in an obstructed collecting system

Emphysematous Pyelonephritis

Emphysematous Pyelitis

Emphysematous pyelitis refers to gas localized within the urinary collecting system.

Chronic Pyelonephritis

Xanthogranulomatous Pyelonephritis

Papillary Necrosis

Tuberculosis

Urinary tract tuberculosis (TB) occurs with hematogenous seeding of the kidney by Mycobacterium tuberculosis from an extraurinary source (typically lung).

Fungal Infections

Candida albicans(fungal ball)

Parasitic Infections

Three parasitic infections of the urinary tract:

• 1.schistosomiasis,
• 2;echinococcal (hydatid) disease, and

3.filariasis.

Schistosomiasis

Schistosoma haematobium is the most common agent to affect the urinary tract

Echinococcal (Hydatid) Disease

Filariasis

Obstruction and Calculus of the Kidney

Hydronephrosis(rerfe to previous lectures)

• Cause
• Obstruction of the urinary tract
• Clinical findings
• Flank pain
• Hematuria
• Fever

Leukocytosis

Grade 1

• Small fluid-filled separation of the renal pelvis

Grade 2

• Dilation of some but not all calyces

Grade 3

• Marked dilation of renal pelvis and all calyces
• Echogenic line separating the collecting system from the parenchyma can be demonstrated

Grade 4

• Prominent dilatation of collecting system
• Cortical thinning
• Unable to separate collecting system and renal parenchyma

Regardless of the grade evaluate bladder for ureteral jets using color Doppler

Ddx

• Extrarenal pelvis
• Parapelvic cyst
• Polycystic disease
• Reflux

Overdistended urinary bladder

Hydroureter

Obstruction of the ureteropelvic junction (UPJ), ureterovesical junction (UVJ), or region where the ureter crosses the pelvic brim Clinical findings

• Asymptomatic

Flank pain

Sono- findings

• Anechoic tubular structure connecting the renal pelvis to the urinary bladder
• No internal blood flow
• Ddx

Fluid filled bowel

Nephrolithiasis-previous lectures

• Cause
• Urinary stasis
• Clinical findings
• Asymptomatic
• Renal colic
• Flank pain

Hematuria

Sono- findings

• Hyperechoic focus within the kidney
• Occurs in the corticomedullary junction
• Posterior acoustic shadowing
• Color Doppler Twinkle artifact ddx
• Calcified vessel

Angiomyolipoma

Benign Pathology of the Kidney

Adenoma

Risk Factors:

• Male prevalence (3:1)
• Tobacco use
• Long-term dialysis
• Cause
• Glandular epithelium
• Most common cortical tumor
• Asymptomatic

Hematuria

Sono findings

• Well-defined hypoechoic cortical mass
• Generally small
• Ddx
• Abscess

Complicated cyst

Angiomyolipoma

• Cause
• Composed of fat, blood vessels, and muscle
• Tends to hemorrhage
• Clinical findings
• Asymptomatic
• Flank pain

Gross hematuria

Sono findings

• Well-defined hyperechoic mass
• May distort renal architecture
• Ddx
• Carcinoma
• Junctional parenchymal defect

Lipoma

Lipoma

• Cause
• Composed of fat
• Clinical findings
• Asymptomatic
• sono
• Well-defined hyperechoic mass
• Ddx
• Angiomyolipoma

Junctional parenchymal defect

Medullary sponge kidney

• Cause -Benign congenital condition
• Clinical findings
• Asymptomatic
• sono
• Hyperechoic foci in the region of the renal papillae
• Widening of the distal collecting system
• Ddx
• Nephrolithiasis

Angiomyolipoma

Mesoblastic nephroma

• Cause
• Pediatric parenchymal tumor
• 90% occur in first year of life
• Benign version of the Wilm’s tumor
• Clinical
• Palpable flank mass
• Hematuria
• sono
• Homogeneous hypoechoic mass
• Large solid parenchymal mass
• Typically involves the renal sinus
• Frequently grow through the renal capsule
• Ddx
• Wilms’ tumor

Neuroblastoma

Nephrocalcinosis

• Cause
• Formation of aggregates of calcium in the distal tubules and loops of Henle
• Clinical
• Asymptomatic
• Hyperparathyroidism
• Hypercalcemia
• hypercalciuria
• sono
• Hyperechoic medullary pyramids
• May demonstrate shadowing ddx
• Nephrolithiasis
• Medullary sponge kidney

Angiomyolipoma

Renal sinus lipomatosis

• Cause
• Obesity
• Previous urinary obstruction
• Chronic renal infection
• Steroid therapy
• Clinical findings
• Asymptomatic
• Elevated creatinine
• Sono
• Increase in echogenicity of the renal sinus
• Thinning of the renal cortex
• Normal renal contour
• ddx

Chronic renal failure

Malignant Pathology of the Kidney

Renal cell carcinoma

• Stages:
• Confined to the kidney
• Spread to perinephric fat
• Extension to the renal vein, inferior vena cava (IVC), or lymph nodes
• Extension to near or distant structures
• Cause
• Adenocarcinoma in 85% of cases (renal cell)

Transitional cell carcinoma

Clinical findings

• Painless gross hematuria
• Uncontrolled hypertension
• Palpable mass

Flank pain

Sono-findings

Irregular mass with echogenicity ranging from hypoechoic (larger mass) to hyperechoic (smaller mass) Focal bulge in renal contour

• Indistinct borders
• Hypervascular mass
• Metastasis to the lung, liver, and long bones
• Extension into the renal vein and IVC
• ddx
• Adrenal tumor
• Abscess
• Focal pyelonephritis
• Adenoma

Angiomyolipoma

Wilms’ tumor (nephroblastoma)

Risk Factors:

• Beckwith-Wiedemann syndrome
• Hemihypertrophy
• Sporadic aniridia
• Male prevalence
• Omphalocele
• 5 yrs of age or less
• Clinical findings
• Palpable mass
• Abdominal pain
• Nausea/vomiting
• Gross hematuria

Hypertension

Sono findings

• Predominately solid, well-defined renal mass
• Variable echo pattern
• Echogenic rim
• Occasional calcification (10%)
• Intramural vascular flow
• Displacement of the IVC and aorta
• Metastasis to the renal vein, IVC, liver, contralateral kidney, and lymph nodes
• Ddx
• Neuroblastoma
• Renal carcinoma

Mesoblastic nephroma

Metastases

Cause

Primary malignancy of the bronchus, breast, gastrointestinal tract, contralateral kidney, and non-Hodgkin’s lymphoma Asymptomatic

• Sono
• Multiple small bilateral masses of variable echogenicity
• ddx
• Angiomyolipomas

Renal cell carcinoma

Vascular Disorders of the Kidneys

Infarction

• Cause
• Necrosis of tissue caused by occlusion of the arterial blood supply
• Clinical findings
• Asymptomatic
• Acute back pain
• Hematuria
• Proteinuria
• sono
• Wedge-shaped hypoechoic (acute) or hyperechoic (chronic) defect
• Ddx
• Angiomyolipomas
• Junctional parenchymal defect

Calcified artery

Renal artery stenosis

• Casue
• Atherosclerosis
• Fibromuscular hyperplasia (mid to distal)
• Clinical findings
• Uncontrolled hypertension
• Renal insufficiency
• Abdominal bruit
• Decrease in urine sodium concentration

Hematuria

Sono findings

• Peak systolic velocity greater than 180 cm/s
• Spectral broadening
• Absence of diastolic flow
• Delayed acceleration time

Renal artery ratio greater than 3.5

Visual narrowing of the renal artery by atherosclerosis or thickening of the arterial wall Kidney atrophy

• Kidney infarct
• ddx
• Tortuous artery

Poor Doppler angle

Renal artery aneurysm

• Risk factor:
• Pregnancy
• Fibromuscular dysplasia
• Blunt trauma
• Kawasaki disease
• Intraluminal catheter-induced injury
• Atherosclerosis
• Clinical
• Asymptomatic
• Hypertension
• Flank pain

Hematuria

Doubling of the normal artery

• Artery diameter of 1.5 cm or greater
• Risk of rupture when the diameter exceeds 2 cm
• Ddx
• Tortuous renal artery
• Bifurcation of the renal artery

Renal vein

Arteriovenous fistula

• Cause
• Congenital malformation
• Trauma
• Renal biopsy complication
• cLinical findings

Asymptomatic

sono

• High-peak systolic velocity associated with high diastolic velocity
• Extremely turbulent flow
• ddx

Renal artery stenosis

Renal vein thrombosis

• Risk factors:
• Malignancy
• Primary renal disease
• IVC obstruction
• Systemic lupus erythematosus
• Sickle cell anemia
• Amyloidosis
• Hypercoagulable state
• Cause
• Renal disease
• Surgery
• Trauma
• Dehydration
• Clinical findings
• Flank pain
• Hematuria
• Hypertension
• Proteinuria

Azotemia

Sono

• Increase in vein diameter
• Hypoechoic or complex echoes within the renal vein
• Continuous, minimal, or absent intraluminal venous flow
• Enlarged kidney
• Ddx
• Renal vein tumor extension
• Improper gain or focal zone settings

Improper Doppler settings or angle

Renal vein tumor extension

• Cause
• Renal carcinoma
• Renal lymphoma
• Nephroblastoma

Depends on the underlying cause

Sono-findings

• Increase in vein diameter
• Echogenic mass within the renal vein
• Vascular flow within the mass
• Continuous, minimal, or absent intraluminal venous flow
• Ddx
• Renal vein thrombosis
• Improper gain or focal zone settings

Improper Doppler settings or angle

Urinary bladder

Congenital Abnormalities of the Urinary Bladder

Bladder exstrophy

• Cause
• Failure of the mesoderm to form over the lower abdomen Typically discovered in utero

Or

It happens when the skin over the lower abdominal wall (bottom part of the tummy) does not form properly, so the bladder is open and exposed on the outside of the abdomen.

• Sono -findings
• Lower anterior abdominal wall defect
• Mass protruding from this defect
• Normal bladder not identified ddx
• Omphalocele
• Inguinal hernia

Umbilical hernia

Bladder diverticulum

• Cause
• Bladder wall muscle weakness
• clinical findings
• Asymptomatic
• Urinary tract infection
• Pelvic pain
• sono
• Anechoic pedunculation of the urinary bladder
• Neck of diverticulum is small
• May enlarge when bladder contracts
• Ddx
• Ovarian cyst
• Fluid-filled bowel

Ascites

diverticullum

Bladder ureterocele

• Cause
• Congenital obstruction of the ureteric orifice
• Clinical findings
• Asymptomatic
• Urinary tract infection
• Sono
• Hyperechoic septation seen within the bladder at the ureteric orifice
• Demonstrated when urine enters the bladder
• Ddx
• Artifact
• Bladder tumor

Catheter balloon

Bladder ureterocele

Urachal sinus

• Cause
• Epithelial tube connecting the apex of the bladder with the umbilicus
• Clinical findings
• Asymptomatic
• Fluid draining from the umbilicus

Ddx

Linear tubular structure extending from the apex of the urinary bladder to the umbilicus ddx Rectus abdominis hematoma

Subcutaneous fat

Urachal anomalies

Bladder Agenesis

Bladder Duplication

Pathology of the Urinary Bladder

Bladder calculus

• Cause
• Urinary stasis
• Migrates from the kidney(s)
• Clinical findings
• Asymptomatic
• Hematuria
• Urinary frequency and urgency

Recurrent urinary tract infections

Sono

• Hyperechoic focus within the urinary bladder
• Posterior acoustic shadowing
• Mobile with patient position change
• Ddx
• Intestinal air

Calcified vessel

Cystitis

• Cause
• Infection
• Clinical findings
• Dysuria
• Urinary frequency

Leukocytosis

sono

• Increase in bladder wall thickness

• Bladder sludge

Hematuria

Bladder sludge

• Cause
• Debris in the bladder
• Clinical findings

Asymptomatic

sono

• Homogeneous low-level echoes
• Mobile with patient position change
• Ddx
• Cystitis

Hematuria

Bladder malignancy

• Cause
• Transitional cell carcinoma
• Clinical findings
• Painless hematuria
• Frequent urination

Dysuria

sono

• Echogenic mass
• Irregular margins
• Immobile with patient position change
• Internal vascular blood flow
• Ddx
• Benign tumor
• Bladder sludge
• Ureterocele

Metastatic tumor

Bladder polyp

• Cause
• Papilloma
• Clinical findings
• Asymptomatic

Frequent urination

sono

• Echogenic intraluminal mass
• Smooth margins
• Immobile with patient position change
• Internal vascular flow
• ddx
• Malignant tumor
• Bladder sludge

Ureterocele

Bladder Fistulas

• Fistula from the bladder to the vagina, gut, skin, uterus, and the ureter may occur

Vesicovaginal fistulas are most common

Renal parenchyma disease(read)