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Ultrasound of the urinary tract - Renal infections

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Ultrasound of the urinary tract - Renal infections

  1. 1. Ultrasound of the urinary tract Renal infections Samir Haffar M.D.
  2. 2. 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
  3. 3.  Acute pyelonephritis
  4. 4. 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
  5. 5. 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
  6. 6. Acute pyelonephritis Diffuse renal enlargement Decreased 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.
  7. 7. 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 kidney Small low-attenuation foci (abscess) Findings prompted nephrectomy US is limited in visualization of small micro-abscesses
  8. 8. Fungal ball Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13. Longitudinal US of right kidney Immunocompromised patient Echogenic mass within dilated calyx Confirmed to be a fungus ball
  9. 9. CT (before, immediately after, & at delayed intervals from contrast material injection) is the preferred modality for evaluating acute bacterial pyelonephritis
  10. 10.  Acute focal & multifocal pyelonephritis
  11. 11. 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.
  12. 12. US of acute multifocal pyelonephritis Identical to focal disease but seen in more than one lobe US of acute focal pyelonephritis Sonolucent mass Poorly marginated Extending from medulla to capsule Absence of distinct wall (abscess) Occasional low amplitude echoes Echogenic mass Commonly seen CT scan more sensitive than US to detect focal disease
  13. 13. 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
  14. 14. 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
  15. 15. Acute bacterial pyelonephritis Wedge-shaped hyperechoic focus in upper pole of right kidney US scan of right kidney Color flow US image Diminished flow through involved area Craig WD et al. RadioGraphics 2008 ; 28 : 255 – 276.
  16. 16.  Renal abscess
  17. 17. Renal abscess • Symptoms Fever, chills, & pain in back & abdomen Symptoms 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.
  18. 18. 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 following the evolution of an abscess Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.
  19. 19. Early and mature abscess cavities Craig WD et al. RadioGraphics 2008 ; 28 : 255 – 276. Cavity better defined Well defined border Through transmission Mature abscess Hypoechoic focus from abscess in upper pole of right kidney Early abscess
  20. 20. Renal abscess Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13. Well-defined hypoechoic lesion Posterior through transmission Increased peripheral vascularity
  21. 21. Gas-forming renal abscesses Kao HW et al. J Med Ultrasound 2008 ; 16 : 113 – 122. Large hypoechoic mass Gas causing reverberation artifact Longitudinal US of right kidney Gas-forming renal abscess Axial CECT
  22. 22. It will be difficult to distinguish abscess from renal tumor Radiologic-guided drainage can be helpful
  23. 23.  Pyohydronephrosis
  24. 24. 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 pain No symptoms at all (15% of cases) • Ultrasound Echogenic debris in collecting system Fluid-fluid levels within collecting system Gas in collecting system (dirty shadows) Early diagnosis & treatment is crucial Craig WD et al. RadioGraphics 2008 ; 28 : 255 – 276.
  25. 25. Pyohydronephrosis Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13. Longitudinal US of right kidney Enlarged hydronephrotic kidney Fluid–fluid level in dilated calyces secondary to pus
  26. 26. Pyohydronephrosis Craig WD et al. RadioGraphics 2008 ; 28 : 255 – 276. Dilated collecting system that is nearly completely filled with echogenic debris
  27. 27.  Emphysematous pyelonephritis
  28. 28. Classification & management of EPN Retrospective review of 48 cases based on CT only Clinical risk factors: thrombocytopenia, ARF, mental status changes, shock Huang 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
  29. 29. 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.
  30. 30. Emphysematous pyelonephritis Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13. Longitudinal gray-scale sonogram of left kidney Air within renal parenchyma with reverberation artifact
  31. 31. Compartments of the retroperitoneum
  32. 32. 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
  33. 33. Gas in renal parenchyma Differential diagnosis • Emphysematous pyelonephritis (EPN) • Focal renal abscess • Enterorenal fistula • Trauma to kidney or bladder Surgery Biopsy Bladder catheterization Nephrostomy placement Akhtar AL et al. AJR 2010 ; 194 : WS31 – WS33.
  34. 34.  Xanthogranulomatous pyelonephritis
  35. 35. Xanthogranulomatous pyelonephritis (XGPN) Chronic destructive granulomatous process from atypical immune response to subacute bacterial infection
  36. 36. 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.
  37. 37. US of Xanthogranulomatous Pyelonephritis Definitive preoperative diagnosis extremely difficult • Focal form Mass-like lesion – Mistaken for renal cell carcinoma • Diffuse form (more common) Diffuse renal enlargement Hypoechoic masses: Abscesses (↑ sound transmission) Granulomatous (↓ sound transmission) Echogenic foci (stones) – Acoustic shadow not always present Common extension to perirenal spaces with abscess & fistula CT evaluation more informative than US in XGPN
  38. 38. Xanthogranulomatous pyelonephritis (XGPN) Craig WD et al. RadioGraphics 2008 ; 28 : 255 – 276. Bilateral staghorn calculi Dilated right collecting system CECT scanUS image of right kidney Staghorn calculus with AS Dilated collecting system
  39. 39. US of Xanthogranulomatous pyelonephritis Diffuse renal enlargement with echogenic foci Kao HW et al. J Med Ultrasound 2008 ; 16 : 113 – 122. Right kidney hydronephrosis with stones in lower pole Coronal CECTLongitudinal US of right kidney
  40. 40.  Renal malakoplakia
  41. 41. 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 with these bacteria & bacterial fragments • Bacteria form nidus for calcium phosphate crystals forming small basophilic bodies called Michaelis-Gutmann bodies Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.
  42. 42. 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 infection Fever, irritative voiding symptoms, flank pain • Symptoms of bladder irritability & hematuria may be seen Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.
  43. 43. • Nonspecific • Often mimic other pathology such as renal tumors • Most common US features: Diffuse enlargement of affected kidney Increased echogenicity of renal parenchyma Hypoechoic lesions &distortion of parenchymal echoes US of Renal malakoplakia Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.
  44. 44. Renal malakoplakia Dharmadhikari R & Crisp A. J Ultrasound Med 2006 ; 25 : 1219 – 1222. Enlarged right kidney Well-defined hypoechoic mass occupying lower two thirds Decreased corticomedullary differentiation at upper pole
  45. 45.  Hydatid disease of kidney
  46. 46. 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
  47. 47. 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 mass with septations Thick-walled cystic mass in left kidney Fluid in central part hyperattenuating Posterior coarse peripheral calcifications
  48. 48. Hydatid disease of the kidney Imaging findings depend on stage of cyst growth Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13. Well-defined cystic lesion Multiple internal septae suggestive of daughter cysts Floating membranes of hydatid cyst following rupture of cyst Water lily sign CE 2 CE 3
  49. 49.  Renal tuberculosis
  50. 50. 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 treatment Firm seminal vesicles on digital rectal examination Chronic 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.
  51. 51. US of renal tuberculosis Traditionally described as limited • Mass lesions in renal parenchyma of mixed echogenicity with 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
  52. 52. US of renal tuberculosis Known case of tuberculosis Hypoechoic areas in renal cortex suggestive of lobar caseation Longitudinal US of right kidney Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.
  53. 53. Renal tuberculosis Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13. Hypoechoic areas of caseous necrosis Dense peripheral calcification with posterior acoustic shadowing
  54. 54. Renal tuberculosis Kao HW et al. J Med Ultrasound 2008 ; 16 : 113 – 122. Multiple chunky calcifications in left upper abdomen Abdominal radiography Longitudinal US of left kidney Extensive AS caused by calcifications Morphologic detail of kidney obscured
  55. 55.  HIV-associated nephropathy
  56. 56. 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 without history of medical renal disease, HIVAN must be considered
  57. 57. 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 kidney Loss of corticomedullary differentiation Obliteration of sinus fat
  58. 58. Thank You

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