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Diana Pancu, MD

RENAL ULTRASOUND. Diana Pancu, MD. Objectives. Clinical indications for performing ED renal US Approach to performing the US study Normal anatomy Abnormal findings Clinical Impact. Clinical Indications for ED Renal Ultrasound. Suspected renal colic Colicky flank pain radiating to groin

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Diana Pancu, MD

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  1. RENAL ULTRASOUND Diana Pancu, MD

  2. Objectives • Clinical indications for performing ED renal US • Approach to performing the US study • Normal anatomy • Abnormal findings • Clinical Impact

  3. Clinical Indications for ED Renal Ultrasound • Suspected renal colic • Colicky flank pain radiating to groin • Hematuria • Clinical question: • Presence of hydronephrosis • Absence of other pathology (AAA)

  4. Performing the Study • Patient preparation: • none • Transducer: 3.0MHz or 3.5 MHz • 5.0 MHz for thin patient • Patient positioning • Supine • Posterior oblique, lateral decubitus, prone

  5. Anatomy • Kidneys are retroperitoneal, T12 - L4 • Right kidney is lower than the left kidney • Right kidney is posterio-inferior to liver & gallbladder • Left kidney is inferior-medial to the spleen • Adrenal glands are superior, anterior, medial to each kidney

  6. Anatomy Hepatic Veins Spleen Celiac axis Liver SMA Left kidney Right kidney Renal artery Renal vein AORTA IVC

  7. Renal Scanning Approaches

  8. Right kidney scanning approach: anterior, lateral, posterior Liver is the acoustic window Left kidney: requires a posterior approach, through the spleen Air-filled bowel impedes anterior scanning I LIVER STOMACH SPLEEN AORTA IVC Approach to Scanning K K S

  9. Anatomy • 9-12 cm long, 4-5 cm wide, 3-4 cm thick • Gerota’s fascia encloses kidney, capsule, perinephric fat • Sinus • Hilum: vessels, nerves, lymphatics, ureter • Pelvis: major and minor calyces • Parenchyma surrounds the sinus • Cortex: site of urine formation, contains nephrons • Medulla: contains pyramids that pass urine to minor calyces. Columns of Bertin separate pyramids

  10. Medullary pyramids Kidney Anatomy Minor Calyx Renal artery Major Calyx Renal vein Sinus Ureter Medulla Renal capsule Cortex

  11. Sonographic Appearance • Ureters are normally not seen • Renal pelvis is black when visible • Renal sinus is echogenic due to fat • Medullary pyramids are hypoechoic • Cortex is mid-gray, less echogenic than liver or spleen. • Capsule is smooth and echogenic

  12. Right Kidney Long Axis

  13. Right Kidney Long Axis Anterior Superior Inferior Liver Sinus Cortex Diaphragm Posterior

  14. Right Kidney Short Axis

  15. Right Kidney Short Axis Anterior Left Right GB Liver IVC R Kidney Aorta Renal a. Vertebral Body Posterior

  16. Left Kidney Long Axis

  17. Left Kidney Long Axis Anterior Inferior Superior Rib Shadow Kidney Posterior Spleen

  18. Left Kidney Short Axis

  19. Left Kidney Short Axis Anterior Right Left Liver Spleen L Kidney Posterior

  20. Common Pitfalls in Renal Scanning • Failure to scan both kidneys • Mistaking prominent renal pyramids for hydronephrosis • Mistaking prominent pyramids for cysts • Confusing normal renal arteries for the ureter

  21. Common Pitfalls in Renal Scanning • Failure to scan through the bladder to search for stone at the uretero-vesicular junction • Inability to visualize left kidney due to anterior probe placement • Failure to scan the aorta in suspected renal colic

  22. Normal Variants • Dromedary humps: • Lateral kidney bulge, same echogenicity as the cortex • Hypertrophied column of Bertin: • Cortical tissue indents the renal sinus • Double collecting system: • Sinus divided by a hypertrophied column of Bertin • Horseshoe kidney: • Kidneys are connected, usually at the lower pole • Renal ectopia: • One or both kidneys outside the normal renal fossa

  23. Clinical Indications • Obstructive Uropathy

  24. Nephrolithiasis • 12% of the US population • Incidence of renal colic is 3% with 50% recurrence within 10 years • Manthey DE. Emerg Med Clin North Am.2001; 19(3): 633-54

  25. Radiographic Modalities Radiography • 62% Sensitivity, 67% Specificity • Sharma RN, Shah I, Gupta S, et al: Thermogravimetric analysis of urinary stones. Br J Urol 64:564-566, 1989  

  26. Radiographic Modalities IVP vs. US • Prospective study, 85 patients • Sinclair D, Wilson S, Toi A, et al. Ann Emerg Med 18:556-559, 1989   • ULTRASOUND Sensitivity=85% • Specificity=92% • IVP • Sensitivity=90% • Specificity=94%

  27. Radiographic Modalities ED Ultrasound + KUB vs. IVP • Prospective study, 108 patients Sensitivity = 97% Specificity = 59% Henderson, S, et al: Acad Emerg Med.1998;5:666-671. • Sensitivity = 97% • Specificity = 59% • PPV = 81% • NPV = 92%

  28. Radiographic Modalities Helical CT- Gold Standard • Accurate, fast, no contrast • Identifies presence and size of stone • Location of stone • Level of obstruction • Other sources of pain

  29. Stone on CT • Usually visualized • Not visualized • Stone is extremely small < 1 mm • Stone is of relatively low CT attenuation: Indinavir stones • Stone excluded from imaging due to respiratory variation

  30. Sensitivity Ureteral dilatation 90% Perinephric stranding 82% Collecting system dilatation 83% Renal enlargement 71% Specificity Ureral dilatation 93% Perinephric stranding 93% Collecting system dilatation 94% Renal enlargement 89% Helical CTSecondary Findings Smith. AJR Am J Roentgenol 167:1109-1113, 1996

  31. Location of Stone • 378 patients • Rate of spontaneous stone passage • 22% for proximal ureteral stones • 46% for midureteral stones • 71% for distal ureteral stones • Morse R. J Urol. 1991; 145:263-265

  32. Width of Stone • 520 patients • Rate of spontaneous stone passage • 100% for stones that were 1 mm or smaller in width • 90% for stones 2 to 3 mm • 80% for stones that were 4 mm • 55% for stones that were 5 mm • 35% for stones that were 6 mm • 25% for stones that were 7 mm • 12% for stones that were 8 mm • Ueno A. Urology. 1977; 10:544-546

  33. Radiographic Modalities Ultrasound • Fast • Can identify other causes of pain • Safe in pregnant patients, children

  34. Hydronephrosis Dilatation of the urinary tract at any level secondary to intrinsic and or extrinsic obstruction to urine flow

  35. Intrinsic, acquired Renal lithiasis Neoplasm (renal, ureteral, bladder) Papillary necrosis Ureterocele Blood clot Neurogenic bladder Anticholinergics Pregnancy, PID, uterine prolapse) Diuretics Vesico-ureteral reflux Diabetes insipidus Intrinsic, congenital Stenosis (ureteral, urethral, meatal) Adynamic ureter Spinal cord defects Duplication of the ureter Ureterocele Hydronephrosis

  36. Hydronephrosis in Renal Colic • Sensitivity = 90% • Specificity = 93% • PPV = 92% • NPV = 90% Smith. AJR Am J Roentgenol. 1996; 167:1109-1113 • PPV = 90% • NPV = 89% • Sensitivity = 87% • Specificity = 90% Dalrymple. J Urol. 1997; 159:735-740  

  37. Obstructive Uropathy Grading System - Subjective • Mild • Minimal separation of calyces • Moderate • Dilation of major and minor calyceal system • Severe • Marked dilation of the renal pelvis and thinning of the renal parenchyma

  38. Range of Hydronephrosis Normal Moderate Severe Mild

  39. Mild Hydronephrosis GB Liver Kidney

  40. Moderate - Severe Hydronephrosis GB Kidney Dilated pelvis Liver

  41. Renal Pathology 1. Renal Cysts

  42. Renal Cysts • Arise in the renal cortex, commonly single rather than multiple • Cysts do not communicate; hydronephrosis does • Shape is round or oval • Echo free • Sharp interface between the mass and renal tissue • Large renal cysts may be mistaken for aortic aneurysms

  43. Renal Cysts Liver Scatter 20 Bowel Cyst Kidney

  44. Problems & Pitfalls • Mistaking cysts for hydronephrosis • Mistaking cysts for aortic aneurysm

  45. Case Presentation • 40 yo male presents with complaints of recent severe headaches, diaphoresis, and palpitations • PE anxious male • BP 210/120 HR 145 RR 18 T 99 • Physical exam otherwise normal

  46. Ultrasound of Kidneys Kidney Liver Diaphragm Rib Shadow Mass

  47. Case Development • The patient was managed with alpha and beta-adrenergic blocking agents • Urine studies revealed elevated metanepherine and catecholamine levels • The patient was diagnosed with pheochromocytoma

  48. Renal Pathology 2. Renal Masses

  49. Renal Masses • Ultrasound visualizes most solid and cystic renal masses • Beyond scope of EM ultrasound • Appearance • Irregular borders • Poorly defined interfaces between mass and kidney • Complex masses • Complex ultrasonic appearance • Cysts or solid masses may represent infection or hemorrhage • May have fluid levels

  50. Case Presentation • 35 year old male with history of Crohn’s presents with sudden onset of right flank pain. He is nauseated and has vomited a few times. He reports hematuria and denies fever, dysuria, abdominal pain.

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