1. BOOST training – endoanal US image review Julia R. Fielding, M.D. April 21, 2010

2. 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

3. 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?

4. 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

5. HAC – High anal canal 1 1.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.

6. Normal HAC Key points: Look for puborectalis “V” and find anterior midline – 12:00

7. Problem HAC – too cephalad, cannot assess IAS well Key points: Look for puborectalis “V” and find anterior midline – 12:00

8. Problem HAC1 Posterior angulation – compresses sphincter closest to spine and allows for mucosal overlap anterior to probe. False positive tear 12:00-1:00.

9. HAC2 – high anal canal 2 1.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

10. Normal HAC2 Key finding: EAS is incomplete

11. Tear HAC2 IAS tear 11:00-12:00 or 30 degrees, EAS intact

12. MAC – middle anal canal 1.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

13. Normal MAC Key finding: 2 concentric rings – hypoechoic (IAS) and hyperechoic (EAS)

14. Tear MAC Tear EAS, 12:00-1:00 or 30 degrees, IAS intact Key point: make sure that you are caudal to HAC2!

15. Tear MAC IAS defect: 9:00-4:00 or 210 degrees, EAS thin but intact

16. Pitfall: Scar IAS Key point: No discontinuity IAS

17. 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

18. Normal LAC Key finding: No dark ring, no IAS component

19. 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.