Renal carbuncle

renal carbuncle

Notes #10: Renal Infections / Inflammations / Calcifications / Obstruction

Renal Failure:

also known as uremia toxic condition associated with renal insufficiency symptoms secondary to retention of nitrogenous waste products


High Blood Pressure Nausea, vomiting GI ulcers, inflammations d/t increase serum ammonia Cardiac arrhythmias d/t potassium, Calcium imbalances Edema and fluid retention Anemia d/t decrease in erythropoietin Urine flow changes Dizziness Coma, convulsions Nephrotic Syndrome (not a single entity but a stage in chronic renal disease marked by proteinuria, decreased plasma protein, rise in serum lipids, edema) Elevated BUN, creatinine, ammonia

Acute renal failure:

sudden impairment symptoms develop within hours or a few days usually secondary to radiation, chemical, or toxin exposure, to sudden decrease in blood volume, or to acute infection

Chronic renal failure:

result of chronic renal disease

develops over many years

Major Classifications of Renal Disease:

Type I Renal Disease:

any of a large group of renal medical diseases that originate with injury or infection of the glomeruli and lead to renal failure.

Sonographic Characteristics:

Initially edema and enlargement of the kidney Progressive increase in echogenicity of the cortex Progressive decrease in size Increased definition of cortico- medullary junction Pyramids may appear enlarged as cortex shrinks

Echogenicity of cortex and size of the kidney correspond to severity of disease, prognosis of kidney

Grade 1: Renal cortex echogenicity = liver Grade 2: Renal cortex echogenicity > liver Grade 3: Renal cortex echogenicity = sinus echoes

Small (length <10cm) echogenic kidneys = poor prognosis Normal sized echogenic kidneys = better prognosis

Type II Renal Disease:

Renal Inflammations and miscellaneous renal diseases that originate in the pelvis or medulla. These diseases have multiple causative agents usually coming from the ureter and leading to pyelonephritis. Type II disease may eventually cause renal failure by generalized progression into the cortex. Type II diseases are, however, more variable in appearance and outcome than are Type I.

Sonographic Appearance:

Variable in appearance Show disruption of pyramid - medullary echoes Distort normal anatomy and eliminate corticomedullary boundary definition

Type I Renal Diseases:

Prerenal Origin of Renal Failure:

diminished blood flow to kidneys can lead to interstitial damage Congestive Heart Failure Decreased Blood Volume from hemorrhage or surgery Renal Artery Stenosis Metabolic vascular diseases such as Diabetes Renal Vein Thrombosis (may be secondary to renal cellcarcinoma, retroperitoneal tumors, diabetes)

Sonographic Analysis: Echogenic material within RV or RA Normal Venous Pattern in RV may be absent Vascular calcifications - shadowing in pelvic area


Large group of diseases where the initial pathological involvement is the glomeruli located in the cortex of the kidney Leads to proteinuria, hypertension, and other signs of renal failure.

Causative Agents: Infectious agents carried through the blood system Strep, Malaria, Syphilis

Toxins such as snake venom, drugs, metals, fumes Pressure damage due to PKD, severe hydronephrosis Autoimmune Inflammation due to lupus nephritis, Goodpasture's Syndrome - antibodies to lung, kidney Acute cortical necrosis Ischemic necrosis d/t shock, hemorrhage, burns, Intrarenal arterial stenosis of venous thrombosis toxemia of pregnancy, severe dehydration

May be localized or generalized Leads to increased cortical echogenicity in the area due to necrosis, calcific deposits and fibrosis


Deposition of abnormal protein fibers in amounts sufficient to impair renal function Associated with acute and chronic infections, and immunologic disorders such as rheumatoid arthritis, lupus, certain tumors (especially myeloma), and aging Deposits occur in spleen, liver, kidneys, lymph nodes, heart, lungs, GI tract, throughout body Leads to rubbery consistency - renal failure

Type II Renal Disease:

Acute Tubular Necrosis:

Results from tubular epithelial destruction Toxins common cause Sonographically normal kidneys Symptoms of acute renal failure with nl kidneys - likely ATN Particularly a problem with renal transplants from cadaever


Similar to ATN, but secondary to alcohol or drug abuse In some cases the pyramids may be prominent or swollen

Renal Papillary Necrosis:

Associated with diabetes, severe infantile diarrhea, obstructive uropathy, sickle cell anemia, acute or chronic pyelonephritis, chronic alcoholism Presents with small cystic areas or increased echogenicity in the medulla

Xanthogranulomatous Pyelonephritis:

Inflammatory disease secondary to long-standing obstruction Xanthro = yellow lipid deposits Enlarged kidneys with stones present in majority of cases Staghorn calculi-large stone center Single or multiple renal masses present, usually hypoechoic or anechoic Abscesses filled with yellow lipid usually peripelvic Debris filled dilated calyces May be segmental associated with obstruction of single calyces Distortion of normal anatomy

Bacterial Interstitial Nephritis (Pyelonephritis):

May result from infection, obstruction, urinary stasis Kidney may appear normal initially Decreased echogenicity throughout kidney and enlargement Obliteration of corticomedullary junction - sinus echoes also appear less echogenic, blend into parenchyma Dilated calyces single or multiple

Focal Nephronia, and Abscesses may develop

Symptoms: Fever, chills and flank pain

Localized Infections aka Focal Nephronia, aka Lobal Nephronia, aka Acute Focal Bacterial Nephritis Localized Inflammatory Mass Small ill-defined borders Wedge shaped area of reduced echogenicity without liquidification

Abscess Formation Liquidification, pus formation Better border definition, liquid component Irregular shape Enhancement, Debris, fluid/debris levels Increasing size of mass area

Carbuncle Mature abscess Thick-walled, discrete, complex, round shape, decreasing size

Emphysematous Infection contain gas which cause stong echoes and shadowing

Infection may remain within the kidney of may break throught the renal capsule to the perirenal space where it tends to localize in fat posterior/lateral to the kidney near psoas muscle. May cause elevation of the kidney. Gerota's fascia usually prevents further spread.

Important to visualize renal capsule to determine if intrarenal or perirenal abscess.

Treatment: Drainage of abscess under ultrasound or fluoroscopic guidance Surgical removal of mature abscess Nephrectomy in severe cases

Renal Tuberculosis:

Multiple abscesses with debris common Associated with pulmonary Tb and AIDS Strictures in calyces often lead to hydronephrosis Ascites may develop

Fungus Balls:

Echogenic non-shadowing mass in the collecting system often associated with fever, chills, flank pain. Occurs most usually in patients with lowered resistance, from diabetes, malignancy, chronic illness, or medication.

Differential diagnosis: blood clot, tumor, debris

Renal Sinus Lipomatosis:

Replacement lipomatosis in sinus Kidney may be normal in size or enlarged with increased width of central echoes, thin renal parenchyma Common in older patients Sequelae to chronic stone or inflammation Also a normal variant with obesity, aging

Renal Calcification and Obstruction:

Only 5% of renal failure is due to obstruction, but this is the easiest cause to treat. It is essential to screen all patients with symptoms of renal failure for obstruction so quick surgical intervention can be undertaken.

Obstructive Causes of Hydronephrosis:

1.Congenital atresia of urethra, kinking of ureter, mal-position of ureter

2.Foreign bodies, calculi (urate stones most common), sloughed papillae or blood clot.

10. Corrected obstruction

11. Neurogenic bladder post operative or due to chronic disease

Hydronephrosis generally unilateral and asymptomatic

Pyonephrosis is hydronephrosis with coexisting infection, debris/purulent material in fluid

Symptoms if present vary:

Oliguria if bilateral complete obstruction Polyuria may develop in incomplete obstruction due to inability of tubules to concentrate Change in size or force of urine stream Severe colicky pain to vague flank pain

Amount of Fluid dependent on duration of obstruction and renal output - amount of residual cortex more important than amount of fluid.

Sonographic Appearance:

Mild Hydronephrosis:

Slight separation of pelvis or cystic appearance of calyces, infundibulum connection to pelvis separates from renal cyst.

Moderate Hydronephrosis:

All calyces enlarged, cauliflower shape

Severe Hydronephrosis:

Shape of calyces no longer discernible. Kidney can reach up to 20 times normal size. Thinning of cortex usually apparent.

Sites of Obstruction:

UPJ - ureteral pelvic junction

Most common site for obstruction congenital strictures calculi or foreign body obstruction retroperitoneal tumor impingement

UVJ - ureteral vesicle junction Obstruction most commonly due to extrinsic compression, ex. pelvic lymphoma, pelvic abscess, ovarian mass, or large abdominal mass Right sided obstruction most common in women Dilated ureters seen as tubular anechoic structures running from kidney to bladder or as circular anechoic areas posterior to the bladder on transverse view Color flow of ureteral jets can confirm unilateral UVJ obstruction Ultrasound may not locate site of obstruction in ureter

Bilateral Obstruction: Least common site for obstruction

may be due to bladder outlet or urethral obstruction associated with bladder or prostate tumor or cervical carcinoma spinal cord damage, paralysis of bladder, urethral motility problems, other non-obstructive causes

Lesions confused with Hydronephrosis "False Positives"

Central renal cysts Multicystic Kidney Sinus Lipomatosis Peripelvic cysts Sonolucent renal pyramids Lumbar meningomyelocele Pancreatic Pseudocysts Sonolucent Masses (Lymphoma, Leukemia, other mets) Aneurysm/Varices of Renal Vasculature in renal hilum

Associated with failure to recognize obstruction or hydronephrosis "False Negatives"

Staghorn calculi - shadowing obscures visualization Numerous cysts with superimposed hydronephrosis Acute renal disease - no output of urine so minimal dilation

Associated Pathology:

Urinoma "renal pseudocyst"

escape of urine, encapsulated by body

appears as an anechoic mass usually posterior to kidney between the renal capsule and Gerota's fascia.

Can lead to retroperitoneal fibrosis, perinephric abscess

Nephrolithiasis or renal calculi

Results from calcium salts in renal system More frequent in males than females Overall incidence 0.1% - 6% of the population Can arise anywhere in urinary system, but most common in kidney Causes: Hypercalcuria or hypercalcemia due to geographic location (water source), hyperparathyroidism, Vit D intoxication, malignancy, bone disease, dehydration, or Cushing's disease Large single stones may be located in center of kidney with shadowing apparent (Staghorn calculi). These are named by their appearance on radiography. Multiple smaller stones can be visualized by ultrasound in the pelvis or near the corticomedullary border

Diffuse nephrocalcinosis

Classic - small stones or deposits along the corticomedullary borders

Cortical Calcification

Deposits in parenchyma of the kidney

in severe form the entire cortex is strongly echogenic, may appear similar to severe Type I renal disease May not shadow CT can differentiate from renal disease

Medullary Calcification

Medullary pyramids become echogenic while the cortex retains normal echogenicity May not shadow - microscopic aggregates cause scattering of beam, but no shadows

Primary Hyperoxaluria

Rare, metabolic disease - hereditary Leads to death before adulthood Presents with renal stones in childhood Calcium oxalate deposits in cortex lead to renal failure Hyperechoic cortex with pelvic stones

Calyceal Diverticuli

Cystic extension of calyces

Category: Carbuncle

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