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
8. Approach to Scanning
• 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
IVC
AORTA
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
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
19. Left Kidney Short Axis
Anterior
Posterior
Right Left
Liver
Spleen
L Kidney
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
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%
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
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
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
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
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
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
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.
51. Physical Exam
Young man in moderate distress from pain
• BP 125/67 HR 110 T 98
• Lungs: clear to ascultation
• Heart: Tachycardia without murmur
• Abdomen: soft, non-tender, normal bowel
sounds
• Back: right costo-vertebral angle tenderness
on percussion
54. CT Results
• Bilateral Staghorn Calculi
• Bilateral moderate hydronephrosis
• Right sided 3 mm stone at the UVJ
55. Summary & Take-Home Points
• US is an adjunct in the evaluation of
patients with suspected renal colic
– Evaluate kidneys
– Evaluate aorta
• Scan both kidneys
