TRAIN CERTIFY MAINTAIN
Family Medicine Musculoskeletal (FM MSK)
CURRICULUM
Advanced skills for certification
a. Probe
b. Knobology
i. Preset. Soft tissue, MSK, or small parts.
ii. Start at around 8-10 cm for thigh or gluteal regions. May start at 5 cm for more superficial areas. Adjust as needed.
iii. Gain. Default. Adjust as needed.
c. Patient positioning.
d. Probe orientation
Two orthogonal planes.
e. Probe grip
Pencil grip.
a. External landmark
i. Soft tissue swelling.
ii. Erythema.
iii. Tenderness.
iv. Fluctuance.b. Internal landmark
c. Relevant anatomy
d. Area of interest
Structural layers over the superficial fascial layer of muscle where most infections occur.
e. Adequate view
a. Image generation
i. Landmark.
- Start the scan over unaffected skin adjacent to area of suspected pathology to identify the normal anatomy.
- End scan when AOI imaged in 2 orthogonal planes.
ii. Optimize image
- Decrease or increase depth as needed-bony cortex should be seen far field with rest of screen filled with all other layers.
- Increase probe frequency for superficial structures.
- Using a standoff pad or water bath for smaller more superficial structures is recommended.
iii. Technique
For areas where bone can be visible in far field (mostly upper and lower limbs):
- Start scan a few cm above affected area with probe indicator towards patient’s right\operator’s left.
- Slide to centre bone on screen.
- Sweep to make bone cortex appear well-defined (thin, bright white).
- Slide caudally until a few cm below affected area.
- Repeat maneuver by sliding probe above-below-above in a lawn mowing fashion going over AOI.
- Scan 1-2 cm of the area adjacent to the area of suspected trauma.
- Rotate probe 90 degrees with probe marker towards patient’s head\proximal\ceiling.
- Slide side to side in the same lawn mowing fashion going over the AOI.
iv. Interrogate AOI
- Scan the area of interest in 2 orthogonal planes.
- Scan in a lawn mowing pattern over the affected area.
- Scan at least 2 cm beyond borders of affected area.
b. Image interpretation
The following areas should be evaluated and a binary yes/no conclusion made:
i. Cellulitis? (YES/NO).
ii. Abscess? (YES/NO).
iii. Necrotizing fasciitis? (YES/NO).
a. Modify depth and probe frequency as needed.
a. Technique
i. Make sure to complete all scans by lawn mowing over entire area even if you’ve already found an abscess pocket! Satellite or secondary abscess pockets are often present in the affected area and missed if AOI not fully scrutinized!
b. Image interpretation
i. Lymph nodes can be mistaken for an abscess or a clotted vessel. Remember that:
- Lymph nodes will present with:
- Hyperechoic centre.
- Hypoechoic rim.
- Color-Doppler flow signal with low velocity INSIDE it.
- No change in structure’s appearance when seen in different planes (keeps its ‘round’ appearance in long AND short axis.
- Abscesses will present with:
- Irregular white border.
- Mixed echogenicity centre (inflammatory fluid, pus, debris)
- A LOT of posterior acoustic enhancement.
- Squish-sign where debris can be seen swirling inside the structure and away from probe when direct pressure is applied.
- No Color-Doppler flow seen inside structure but hyperemia often seen AROUND structure (‘Ring of fire’ appearance).
- Vascular structures or pseudoaneurysms can be mistaken for an abscess or a lymph node. Remember that vascular structures will present with:
- Anechoic centre with white membrane around it.
- Change of appearance when imaged in different planes (round in short axis and tubular in long axis).
- Strong, pulsatile Color-Doppler flow signal INSIDE structure.
- Veins can be easily and completely collapsed with pressure if clot-free.
c. Clinical integration
i. Findings for cellulitis and edema are the same. Clinical presentation will be paramount in helping you differentiate between the two entities.
ii. Necrotizing fasciitis: Ultrasound lacks sufficient sensitivity to rule out necrotizing fasciitis. It should never be used when there are other clinical indicators of a necrotizing infection. Prompt surgical consult needs to be pursued even if the scan is technically ‘negative’ for necrotizing fasciitis.
- Subcutaneous air is pathognomonic. Looks like lung findings in the SQ layers!
- Fluid observed along a fascial plane increases specificity for necrotizing fasciitis.
- More fluid = more specific. At 5 mm of fluid, you get a specificity of around 97.9%!
- Is a life-and-limb surgical and medical emergency: prompt treatment and surgical consult needed.
iii. Some deep abscesses, like ischiorectal abscesses, can’t be well assessed with POCUS. If high clinical suspicion remains, think about using other imaging modalities.
a. Make sure to cover the transducer with a probe cover to minimize transfer of patient’s bacterial flora onto transducer’s head and vice versa.
b. Squish-sign for abscess. Fluid can be visualized swirling inside the abscess when pressure is applied and released.
c. When in doubt, compare to unaffected side.
d. Measure dimensions and depth of abscess and delineate area on skin as needed.
e. If lost because of lots of soft tissue disruption seen on screen, start your assessment from bone to skin instead! Bone will always look like bone.
a. For a negative scan:
i. Must image from skin through soft tissue layers to bony cortex in 2 orthogonal planes over AOI.
ii. Must interrogate at least 2 cm beyond borders of affected area if anatomically possible.
iii. No pathology is found.
b. For a positive scan for CELLULITIS:
i. Thickening of subcutaneous layers is identified.
ii. Anechoic fluid tracks between fat lobules aka “cobblestoning” is identified.
iii. Must complete scan even if one positive is identified to assess for other possible findings.
c. For a positive scan for ABSCESS:
i. Irregular bordered pocket of fluid with mixed echogenicity is identified.
ii. Squish-sign is present.
iii. Posterior acoustic enhancement is present.
iv. Must complete scan even if one positive is identified to assess for other possible findings.
d. For a positive scan for NECROTIZING FASCIITIS:
i. Thickening of subcutaneous layers is identified.
ii. Fluid along the fascial plane and/or subcutaneous air is identified.
Document as per CPoCUS guidelines for positives and negatives according to clinical indications:
a. Cellulitis + or –
b. Abscess + or –
c. Necrotizing fasciitis + or –
d. Indeterminate
Prerequisites
Appropriate didactic and practical introduction to technique that must include written materials covering all relevant ultrasound physics, anatomy and theory, a minimum of 30 minutes of live or on-line lectures, and at least 5 introductory proctored soft tissue layers scans.
The introductory scans do not count towards certification and do not need to be determinate.
Logged scan requirements
- 2-3 soft tissue layers determinate scans supervised directly by a CPoCUS MSK Track Instructor for the entirety of the scan.
- Determinate scans are defined in ‘Determinate scan requirements’.
- A minimum of x scans (to be determined) must be done ‘unassisted’.
- An unassisted scan is one in which the learner generates a determinate image and uses appropriate troubleshooting maneuvers without any assistance (verbal or physical) from the instructor.
- There is no requirement for a minimum number of positive scans.
- All scans must be recorded in a CPoCUS logbook.
Examinations
Pass mark on CPoCUS soft tissue layers written, practical, and visual examinations PLUS appropriate prerequisites AND logged scans as above.
Note: Prerequisites and/or logged scan requirements may be waived if a candidate is awarded a CPoCUS Exception to Certification (see website for application details).
a. Probe
b. Knobology
i. Preset. Soft tissue, MSK, or small parts.
ii. Depends on affected area. Start at depth around 4 cm. Adjust as needed.
iii. Gain. Default. Adjust as needed.
c. Patient positioning.
d. Probe orientation
e. Probe grip
Pencil grip.
a. External landmark
i. Wound.
ii. Puncture.
iii. Tenderness.
b. Internal landmark
c. Relevant anatomy
d. Area of interest
e. Adequate view
a. Image generation
i. Landmark.
- Start scan just above the affected area.
- End scan when AOI imaged in 2 planes.
ii. Optimize image
- Decrease or increase depth depending on location of suspected FB.
- Increase probe frequency.
- Use of standoff pad or water bath for smaller body parts or very superficial foreign bodies is recommended.
iii. Technique
- Start scan 1-2 cm above affected area (if anatomically feasible) with probe marker towards patient’s right\operator’s left.
- Slide caudally until 1-2 cm below affected area.
- Look for underlying artifacts caused by the FB:
- Posterior acoustic shadowing (most wood, glass, bone or plastic FBs).
- Reverberation (mostly metal FB).
- Comet-tail artifacts (mostly metal or glass FB).
- Hypo-echoic halo surrounding FB due to prolonged retention of FB, granulation and abscess formation.
- Repeat maneuver by sliding probe above-below-above in a lawn mowing fashion going over AOI.
- Scan 1-2 cm of the area adjacent to the area of suspected FB.
- Rotate probe 90 degrees with probe marker towards patient’s head\proximal\ceiling.
- Slide side to side in the same lawn mowing fashion going over the AOI.
iv. Interrogate AOI
- Slowly scan the area of interest in 2 planes in a lawn mowing pattern in order not to miss a small FB.
b. Image interpretation
The following areas should be evaluated and a binary yes/no conclusion made:
i. Foreign body? (YES/NO).
a. Modify depth and probe frequency as needed.
a. Technique
i. Smaller areas like hands\digits and feet\toes are harder to scan. Use a water bath to improve visualization.
b. Image interpretation
i. Normal structures can be mistaken for a FB (remember that most FBs are HYPERechoic on ultrasound).
ii. You may see more than one artifact for a single FB so look carefully!
iii. Small foreign bodies <5 mm may present without any artifacts (but most FBs will appear HYPERechoic on ultrasound.
c. Clinical integration
i. If high clinical suspicion for FB remains and POCUS exam negative, use other imaging modalities as needed.
a. Make sure to cover the transducer with a probe cover to minimize transfer of patient’s bacterial flora onto transducer’s head and vice versa.
b. Compare with unaffected side when in doubt.
c. Mark location of FB on patient’s skin.
d. Trauma to surrounding soft tissue is decreased whenever FB is removed through original injury track.
e. Once found, try to remove FB under real-time US-guidance.
a. For a negative scan:
i. Must image area of suspected foreign body in 2 planes.
ii. No FB is identified.
b. For a positive scan:
i. Must image area of suspected foreign body in 2 planes.
ii. Hyperechoic surface of the foreign body is identified.
iii. Underlying artifacts are identified.
iv. +/- Hypoechoic “halo ring” around the foreign body is identified.
Document as per CPoCUS guidelines for positives and negatives according to clinical indications:
a. Foreign body + or –
b. Indeterminate
Prerequisites
Appropriate didactic and practical introduction to technique that must include written materials covering all relevant ultrasound physics, anatomy and theory, a minimum of 30 minutes of live or on-line lectures, and at least 5 introductory proctored soft tissue FB scans.
The introductory scans do not count towards certification and do not need to be determinate.
Logged scan requirements
- 1-2 soft tissue foreign body determinate scans supervised directly by a CPoCUS MSK Track Instructor for the entirety of the scan.
- Determinate scans are defined in ‘Determinate scan requirements’.
- A minimum of x scans (to be determined) must be done ‘unassisted’.
- An unassisted scan is one in which the learner generates a determinate image and uses appropriate troubleshooting maneuvers without any assistance (verbal or physical) from the instructor.
- There is no requirement for a minimum number of positive scans.
- All scans must be recorded in a CPoCUS logbook.
Examinations
Pass mark on CPoCUS soft tissue FB written, practical, and visual examinations PLUS appropriate prerequisites AND logged scans as above.
Note: Prerequisites and/or logged scan requirements may be waived if a candidate is awarded a CPoCUS Exception to Certification (see website for application details).