boost training – endoanal us image review
DESCRIPTION
BOOST training – endoanal US image review . Julia R. Fielding, M.D. April 21, 2010. Objectives. 1. Review appearance of normal sphincter complex on US exams compared with line drawings 2. Show examples of sphincter tears at multiple levels 3. Show errors in technique - PowerPoint PPT PresentationTRANSCRIPT
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BOOST training – endoanal US image review
Julia R. Fielding, M.D.April 21, 2010
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Objectives
• 1. Review appearance of normal sphincter complex on US exams compared with line drawings
• 2. Show examples of sphincter tears at multiple levels
• 3. Show errors in technique• 4. Tips of the trade – make your life easier
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Image analysis
• Is this exam too bright (overexposed) or too dark (underexposed)? Is your gain setting appropriate (brightness)?
• Is this exam interpretable?• Ask yourself these questions WHILE you are
doing the exam – Is your machine working correctly? Is the patient as comfortable as possible?
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Image analysis
• Location – HAC1, HAC2, MAC and LAC• Tear IAS – discontinuity in dark ring• Tear EAS – discontinuity in bright ring• If tear, how large – clock-face and radial
degrees
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HAC – High anal canal 11. This is the superior
most image of the exam.
2. Probe should be perpendicular to sphincter – puborectalis muscle is symmetric in appearance and makes a “V”
3. This “sets the clock” for the entirety of the exam.
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Normal HAC
Key points: Look for puborectalis “V” and find anterior midline – 12:00
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Problem HAC – too cephalad, cannot assess IAS well
Key points: Look for puborectalis “V” and find anterior midline – 12:00
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Problem HAC1
Posterior angulation – compresses sphincter closest to spine and allows for mucosal overlap anterior to probe. False positive tear 12:00-1:00.
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HAC2 – high anal canal 21. We will review this
level but it will not be included on the TEST
2. Located just caudal to HAC1
3. Check that probe has not changed position
4. Note that IAS makes a ring and EAS is incomplete
5. No “V” present
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Normal HAC2
Key finding: EAS is incomplete
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Tear HAC2
IAS tear 11:00-12:00 or 30 degrees, EAS intact
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MAC – middle anal canal1. Check your position –
probe without ANGULATION or ROTATION.
2. Rotation resets the clock and causes errors in recording LOCATION of tear.
3. Angulation compresses one portion of the sphincter complex more than another leading to FALSE POSITIVE tear assessment
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Normal MAC
Key finding: 2 concentric rings – hypoechoic (IAS) and hyperechoic (EAS)
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Tear MAC
Tear EAS, 12:00-1:00 or 30 degrees, IAS intactKey point: make sure that you are caudal to HAC2!
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Tear MAC
IAS defect: 9:00-4:00 or 210 degrees, EAS thin but intact
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Pitfall: Scar IAS
Key point: No discontinuity IAS
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LAC- Lower anal canal
1. This is the most caudal of the images
2. The IAS – black concentric ring, has disappeared
3. All that remains is the EAS, the hyperechoic ring
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Normal LAC
Key finding: No dark ring, no IAS component
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Problem LAC
Image too bright, overexposed, also portions of IAS are still visible, so image is a bit too cephalad. This exam would be considered “overexposed” If no better image available, then uninterpretable.