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Ultrasound of the urinary tract Renal infections Samir Haffar M.D.
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Ultrasound of the urinary tract - Renal infections

Aug 22, 2014

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Page 1: Ultrasound of the urinary tract - Renal infections

Ultrasound of the urinary tract

Renal infections

Samir Haffar M.D.

Page 2: Ultrasound of the urinary tract - Renal infections

Renal infections

Acute pyelonephritis Acute focal & multifocal pyelonephritis Renal abscess Pyonephrosis Emphysematous pyelonephritis Xanthogranulomatous pyelonephritis Renal malakoplakia Hydatid disease of kidney Renal tuberculosis HIV-associated nephropathy

Page 3: Ultrasound of the urinary tract - Renal infections

Acute pyelonephritis

Page 4: Ultrasound of the urinary tract - Renal infections

Acute pyelonephritis

• Symptoms Flank pain, costovertebral angle tenderness Fever, chills, nausea, & vomiting Lower symptoms: dysuria, frequency, urgency

• Laboratory Neutrophilic leukocytosis, elevated ESR & C-RP Elevation of serum creatinine in severe infection

• Urinalysis Numerous leukocytes & bacteria Presence of leukocyte esterase & nitrites Sterile urine (obstruction of infected kidney)

• Causes Bacterial: EC in 80% Fungal: Candida albicans & tropicalis – Fungal

balls

Page 5: Ultrasound of the urinary tract - Renal infections

US of acute pyelonephritis

US abnormalities (20 %)

Renal enlargement (> 15 cm – affected kidney > 1.5 cm longer ) Hypoechoic renal parenchyma Loss of corticomedullary differentiation

Loss of renal sinus fat Dilatation of collecting system without obstructive cause Abscess formation

Rumack CM et al. Diagnostic Ultrasound. Elsevier-Mosby, St. Louis, USA, 3rd edition, 2005.

Majority of cases (80 %)

Normal-appearing kidney – Routine Imaging not required

Page 6: Ultrasound of the urinary tract - Renal infections

Acute pyelonephritis

Diffuse renal enlargementDecreased echogenicity

Loss of corticomedullary differentiation

Longitudinal US of left kidney Longitudinal US of right kidney

Normal right kidney

Kao HW et al. J Med Ultrasound 2008 ; 16 : 113 – 122.

Page 7: Ultrasound of the urinary tract - Renal infections

Severe acute bacterial pyelonephritis

Craig WD et al. RadioGraphics 2008 ; 28 : 255 – 276.

Slightly enlarged right kidney that is otherwise unremarkable

despite advanced disease

US image of right kidney Abdominal CT scan

Enlarged kidneySmall low-attenuation foci (abscess)

Findings prompted nephrectomy

US is limited in visualization of small micro-abscesses

Page 8: Ultrasound of the urinary tract - Renal infections

Fungal ball

Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.

Longitudinal US of right kidneyImmunocompromised patient

Echogenic mass within dilated calyxConfirmed to be a fungus ball

Page 9: Ultrasound of the urinary tract - Renal infections

CT (before, immediately after, & at delayed intervals from contrast material injection)

is the preferred modality for evaluatingacute bacterial pyelonephritis

Page 10: Ultrasound of the urinary tract - Renal infections

Acute focal & multifocal pyelonephritis

Page 11: Ultrasound of the urinary tract - Renal infections

Acute focal & multifocal pyelonephritis

• Focal PN Infection confined to single lobe Multifocal PN Infection confined to multiple lobes

• Risk factors DM – immunosuppression

• Clinical features More severe symptoms than APL Commonly progresses to sepsis

• Treatment Similar to other cases of APL 7 days of parenteral antibiotics Then 7day of oral antibiotics

Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.

Page 12: Ultrasound of the urinary tract - Renal infections

US of acute multifocal pyelonephritis

Identical to focal disease but seen in more than one lobe

US of acute focal pyelonephritis

Sonolucent mass Poorly marginatedExtending from medulla to capsuleAbsence of distinct wall (abscess) Occasional low amplitude echoes

Echogenic mass Commonly seen

CT scan more sensitive than US to detect focal disease

Page 13: Ultrasound of the urinary tract - Renal infections

Acute focal pyelonephritis

Infection confined to single lobe

Rubens DJ et al. Ultrasound Clin 2007 ; 2 : 391 – 413.

Decreased attenuation area

Typical of focal pyelonephritis

3-cm echogenic mass in lower pole of right kidney

CT scan more sensitive than US to detect focal pyelonephritis

Page 14: Ultrasound of the urinary tract - Renal infections

Acute multifocal pyelonephritis

Infection confined to multiple lobes

Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.

Absence of color flow

Color Doppler

2 wedge-shaped areas of decreased echogenicity in renal cortex

Transverse US of right kidney

Page 15: Ultrasound of the urinary tract - Renal infections

Acute bacterial pyelonephritis

Wedge-shaped hyperechoic focusin upper pole of right kidney

US scan of right kidney Color flow US image

Diminished flow throughinvolved area

Craig WD et al. RadioGraphics 2008 ; 28 : 255 – 276.

Page 16: Ultrasound of the urinary tract - Renal infections

Renal abscess

Page 17: Ultrasound of the urinary tract - Renal infections

Renal abscess

• Symptoms Fever, chills, & pain in back & abdomenSymptoms of urinary tract infection

• Hig risk DM, hemodialysis, IV drug abusers

• Causes Renal carbuncles before antibiotics: SA

Ascending infection: EC, Klebsiella, Proteus

• Management < 3 cm Parenteral antibiotics 3 – 5 cm Percutaneous drainage > 5 cm Surgical drainage

Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.

Page 18: Ultrasound of the urinary tract - Renal infections

US of renal abscess

• Hypoechoic mass with thick irregular walls or capsule

• Indistinct margins acutely & distinct wall thereafter

• Increased through-transmission

• Occasional development of fluid debris level

• Gas in hypoechoic/cystic mass strongly suggests abscess

Serial US examinations are essential in followingthe evolution of an abscess

Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.

Page 19: Ultrasound of the urinary tract - Renal infections

Early and mature abscess cavities

Craig WD et al. RadioGraphics 2008 ; 28 : 255 – 276.

Cavity better definedWell defined border

Through transmission

Mature abscess

Hypoechoic focus from abscessin upper pole of right kidney

Early abscess

Page 20: Ultrasound of the urinary tract - Renal infections

Renal abscess

Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.

Well-defined hypoechoic lesion Posterior through transmission

Increased peripheral vascularity

Page 21: Ultrasound of the urinary tract - Renal infections

Gas-forming renal abscesses

Kao HW et al. J Med Ultrasound 2008 ; 16 : 113 – 122.

Large hypoechoic massGas causing reverberation artifact

Longitudinal US of right kidney

Gas-forming renal abscess

Axial CECT

Page 22: Ultrasound of the urinary tract - Renal infections

It will be difficult to distinguish abscess from renal tumor

Radiologic-guided drainage can be helpful

Page 23: Ultrasound of the urinary tract - Renal infections

Pyohydronephrosis

Page 24: Ultrasound of the urinary tract - Renal infections

Pyohydronephrosis Infection of obstructed collecting system

• Obstruction Stone, tumor, sloughed papilla, stricture• Complications Decline in renal function, septic shock• Symptoms UT obstruction with flank pain & fever

Subtle symptoms: weight loss, dull painNo symptoms at all (15% of cases)

• Ultrasound Echogenic debris in collecting system Fluid-fluid levels within collecting systemGas in collecting system (dirty shadows)

Early diagnosis & treatment is crucial

Craig WD et al. RadioGraphics 2008 ; 28 : 255 – 276.

Page 25: Ultrasound of the urinary tract - Renal infections

Pyohydronephrosis

Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.

Longitudinal US of right kidneyEnlarged hydronephrotic kidney

Fluid–fluid level in dilated calyces secondary to pus

Page 26: Ultrasound of the urinary tract - Renal infections

Pyohydronephrosis

Craig WD et al. RadioGraphics 2008 ; 28 : 255 – 276.

Dilated collecting systemthat is nearly completely filled with echogenic debris

Page 27: Ultrasound of the urinary tract - Renal infections

Emphysematous pyelonephritis

Page 28: Ultrasound of the urinary tract - Renal infections

Classification & management of EPN

Retrospective review of 48 cases based on CT only

Clinical risk factors: thrombocytopenia, ARF, mental status changes, shockHuang JJ et al. Arch Intern Med 2000 ; 160 : 797 – 805.

Radiologic class

Finding on CT

Management

Class 1 Gas in collecting system only IV antibiotics PCD Decompression of UT obstruction

Class 2 Gas in renal parenchyma No extension to perirenal space

IV antibiotics PCD Decompression of UT obstruction

Class 3A Extension of gas or abscess to perirenal space

IV antibiotics Immediate nephrectomy if risk factors

Class 3B Extension of gas or abscess to pararenal space

IV antibiotics Immediate nephrectomy if risk factors

Class 4 Bilateral EPN or solitary functioning kidney with EPN

IV antibiotics & PCD Nephrectomy if failed

Page 29: Ultrasound of the urinary tract - Renal infections

US in emphysematous pyelonephritis

• Enlarged kidney

• High amplitude echoes within renal parenchyma

• Low-level posterior dirty acoustic shadowing

• Depth of parenchymal involvement underestimated by US

Isolated presence of gas within collecting system seen after many interventional procedures

CT always warranted & considered ideal study to visualize extent & amount of gas

Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.

Page 30: Ultrasound of the urinary tract - Renal infections

Emphysematous pyelonephritis

Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.

Longitudinal gray-scale sonogram of left kidneyAir within renal parenchyma with reverberation artifact

Page 31: Ultrasound of the urinary tract - Renal infections

Compartments of the retroperitoneum

Page 32: Ultrasound of the urinary tract - Renal infections

Emphysematous pyelonephritis

Tajima K et al. N Engl J Med 2007 ; 356 ; 526 – 527.

Gas throughout right kidney

Abdominal radiograph CT scan of abdomen

Extensive destruction of renal parenchyma with associated gas

Gas in retroperitoneal tissues

Page 33: Ultrasound of the urinary tract - Renal infections

Gas in renal parenchymaDifferential diagnosis

• Emphysematous pyelonephritis (EPN)

• Focal renal abscess

• Enterorenal fistula

• Trauma to kidney or bladder SurgeryBiopsyBladder catheterizationNephrostomy placement

Akhtar AL et al. AJR 2010 ; 194 : WS31 – WS33.

Page 34: Ultrasound of the urinary tract - Renal infections

Xanthogranulomatous pyelonephritis

Page 35: Ultrasound of the urinary tract - Renal infections

Xanthogranulomatous pyelonephritis (XGPN)

Chronic destructive granulomatous process from atypical

immune response to subacute bacterial infection

Page 36: Ultrasound of the urinary tract - Renal infections

Xanthogranulomatous Pyelonephritis (XGPN) Rare inflammatory condition

• Long-term & recurrent obstruction from stone with infection

• Replacement of parenchyma by lipid-laden macrophages

• Most common organism: Proteus mirabilis or E. Coli

• Adults in fifth to seventh decade – Women in 70%

• Nonspecific symptoms: malaise, flank pain, low-grade fever

• Nephrectomy is the standard approach for diagnostic & tt

• Excellent prognosis

Kao HW et al. J Med Ultrasound 2008 ; 16 : 113 – 122.

Page 37: Ultrasound of the urinary tract - Renal infections

US of Xanthogranulomatous PyelonephritisDefinitive preoperative diagnosis extremely difficult

• Focal formMass-like lesion – Mistaken for renal cell carcinoma

• Diffuse form (more common)Diffuse renal enlargementHypoechoic masses: Abscesses (↑ sound transmission) Granulomatous (↓ sound transmission)Echogenic foci (stones) – Acoustic shadow not always presentCommon extension to perirenal spaces with abscess & fistula

CT evaluation more informative than US in XGPN

Page 38: Ultrasound of the urinary tract - Renal infections

Xanthogranulomatous pyelonephritis (XGPN)

Craig WD et al. RadioGraphics 2008 ; 28 : 255 – 276.

Bilateral staghorn calculiDilated right collecting system

CECT scanUS image of right kidney

Staghorn calculus with ASDilated collecting system

Page 39: Ultrasound of the urinary tract - Renal infections

US of Xanthogranulomatous pyelonephritis

Diffuse renal enlargementwith echogenic foci

Kao HW et al. J Med Ultrasound 2008 ; 16 : 113 – 122.

Right kidney hydronephrosiswith stones in lower pole

Coronal CECTLongitudinal US of right kidney

Page 40: Ultrasound of the urinary tract - Renal infections

Renal malakoplakia

Page 41: Ultrasound of the urinary tract - Renal infections

Renal malakoplakia Rare inflammatory disorder

• Chronic gram-negative urinary tract infection (E. coli)

• Deposition of soft, yellow plaques in bladder & urinary tract

• Abnormal macrophage function causing incomplete intracellular bacterial lysis.

• Deposition of histiocytes (von Hansemann cells) filled withthese bacteria & bacterial fragments

• Bacteria form nidus for calcium phosphate crystals formingsmall basophilic bodies called Michaelis-Gutmann bodies

Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.

Page 42: Ultrasound of the urinary tract - Renal infections

Renal malakoplakia

• Usually occurs in women

• Most patients older than 50 years

• Underlying condition compromising immune system:Diabetes, immunosuppression, chronic debilitating disease

• Symptoms of urinary tract infectionFever, irritative voiding symptoms, flank pain

• Symptoms of bladder irritability & hematuria may be seen

Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.

Page 43: Ultrasound of the urinary tract - Renal infections

• Nonspecific

• Often mimic other pathology such as renal tumors

• Most common US features:Diffuse enlargement of affected kidneyIncreased echogenicity of renal parenchymaHypoechoic lesions &distortion of parenchymal echoes

US of Renal malakoplakia

Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.

Page 44: Ultrasound of the urinary tract - Renal infections

Renal malakoplakia

Dharmadhikari R & Crisp A. J Ultrasound Med 2006 ; 25 : 1219 – 1222.

Enlarged right kidneyWell-defined hypoechoic mass occupying lower two thirdsDecreased corticomedullary differentiation at upper pole

Page 45: Ultrasound of the urinary tract - Renal infections

Hydatid disease of kidney

Page 46: Ultrasound of the urinary tract - Renal infections

WHO classification of cystic echinococcosis (CE)International consensus classification

5 types on the basis of US appearances

CE I

Unilocular simple cysts

CE 3

CE 2

CE 4

CE 5

WHO Informal Working Group. Acta Trop 2003 ; 85 : 253 – 261.

Floating membrane (water lily sign)

Multivesicular multiseptated cyst

Heterogeneous degenerative contents

Thick calcified wall

Active

Transitional

Active

Inactive

Inactive

Page 47: Ultrasound of the urinary tract - Renal infections

Hydatid disease of kidney (very rare)Imaging findings depend on stage of cyst growth

Volders WK et al. RadioGraphics 2001 ; 21 : S255 – S260.

Multicystic hypoechoic masswith septations

Thick-walled cystic mass in left kidneyFluid in central part hyperattenuating

Posterior coarse peripheral calcifications

Page 48: Ultrasound of the urinary tract - Renal infections

Hydatid disease of the kidneyImaging findings depend on stage of cyst growth

Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.

Well-defined cystic lesionMultiple internal septae

suggestive of daughter cysts

Floating membranes of hydatid cyst

following rupture of cystWater lily signCE 2 CE 3

Page 49: Ultrasound of the urinary tract - Renal infections

Renal tuberculosis

Page 50: Ultrasound of the urinary tract - Renal infections

Renal tuberculosis

• Considered in patients with history of tuberculosis

• Often asymptomatically even in advanced disease

• ¼ of patients present with unilateral poorly functioning kidney• Other suspicious findings

Chronic cystitis or epididymitis recalcitrant to treatmentFirm seminal vesicles on digital rectal examinationChronic fistula tract that forms at surgical sites

• Dg: urine culture demonstrating growth of M tuberculosis.

Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.

Page 51: Ultrasound of the urinary tract - Renal infections

US of renal tuberculosis

Traditionally described as limited

• Mass lesions in renal parenchyma of mixed echogenicitywith or without necrotic areas & calcifications

• Mucosal thickening & stenosis of calyces

• Mucosal thickening of renal pelvis & ureter

• Ureteral stricture & hydronephrosis

• Bladder changes: mucosal thickening & reduced capacity

Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.

Role of high-resolution ultrasonography

Page 52: Ultrasound of the urinary tract - Renal infections

US of renal tuberculosis

Known case of tuberculosisHypoechoic areas in renal cortex suggestive of lobar caseation

Longitudinal US of right kidney

Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.

Page 53: Ultrasound of the urinary tract - Renal infections

Renal tuberculosis

Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.

Hypoechoic areas of caseous necrosis Dense peripheral calcification with posterior acoustic shadowing

Page 54: Ultrasound of the urinary tract - Renal infections

Renal tuberculosis

Kao HW et al. J Med Ultrasound 2008 ; 16 : 113 – 122.

Multiple chunky calcificationsin left upper abdomen

Abdominal radiography Longitudinal US of left kidney

Extensive AS caused by calcificationsMorphologic detail of kidney obscured

Page 55: Ultrasound of the urinary tract - Renal infections

HIV-associated nephropathy

Page 56: Ultrasound of the urinary tract - Renal infections

HIV-associated nephropathy (HIVAN)

Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.

Major sonographic findings Enlarged kidney

Increased cortical echogenicity

Loss of corticomedullary differentiation

Obliteration of sinus fat

In increased cortical echogenicity in a young patient withouthistory of medical renal disease, HIVAN must be considered

Page 57: Ultrasound of the urinary tract - Renal infections

HIV-associated nephropathy (HIVAN)

Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.

Transverse US of right kidneyLongitudinal US of right kidney

Enlarged, markedly echogenic kidneyLoss of corticomedullary differentiation

Obliteration of sinus fat

Page 58: Ultrasound of the urinary tract - Renal infections

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