CM: March 2014

Soft Tissue Ultrasound

The Case

You’re called to evaluate a 32 year old gentleman with a chief complaint of hand pain. You approach the patient and see an obviously swollen, red right hand. The patient explains that he’s a construction worker and accidently shot himself in the hand with a nail gun a week ago. His hand is now warm, erythematous, swollen, and very painful (classic rubor, dolor, calor, tumor). On physical exam the hand is warm and painful to the touch. There is an area of mild fluctuance, but no obvious skin thinning over the area. Pulses are present and sensation is intact. There is no drainage from the original wound at the base of the thenar eminence. The erythema and swelling extends into the wrist and 1 cm up the distal forearm. The patient does not take any medications and has no known medical problems. Review of systems is negative (no fever, chills, malaise, etc) except for the symptoms already noted in the distal right upper extremity. Patient has a mildly elevated WBC count, but otherwise labs are within normal limits. X-ray reveals no fracture or other bony pathology. You think the patient might have an abscess with surrounding cellulitis, but you’re not sure exactly where to attempt drainage. Being the clever clinician you are, you grab a nearby ultrasound and find the image below over the thenar eminence. You see a loculated pocket of pus, which you drain using ultrasound guidance. The patient goes home with antibiotics and you pat yourself on the back for using your awesome ultrasound skills to find and drain a difficult abscess.

Suggested Resources

One Minute Ultrasound: Soft Tissue

SonoGuide: Abscess AND Soft Tissue Ultrasound

Introduction to Bedside Ultrasound: Vol. 2 Ch. 10 “Soft Tissue”

The Quiz

1. Which of the following pathologies can soft tissue ultrasound NOT identify?

A) Abscess
B) Cellulitis
C) Necrotizing fasciitis
D) Foreign objects
E) All of the above soft tissue infections can be identified with ultrasound



2.  What is the best treatment for the pathology shown in the image above?

A) Take the patient to the OR for immediate debridement
B) Incision and drainage
C) Antibiotics alone
D) Nothing, the image above is completely normal

3.  Distinguishing an abscess from cellulitis by physical exam alone can be misleading. What percent of physicians change their management strategy (I&D v. antibiotics alone) of a soft tissue infection after ultrasound is performed? (hint: the answer is in the abscess ultrasound resource and Introduction to Bedside Ultrasound)

A) < 10%
B) 25-30%
C) > 50%
D) 100%

4.  Which of the sonographic sign is incorrectly matched with its pathology?

A) Cellulitis: cobble stoning
B) Cellulitis: twinkle artifact
C) Abscess: anechoic pocket with “pus-stalsis”
D) Abscess: posterior acoustic enhancement
E) Necrotizing fasciitis: gas shadowing

5.  All of the following are reasons to use ultrasound in evaluation of soft tissue infections EXCEPT:

A) It’s a more efficient use of healthcare resources (ultrasound cost less than CT)
B) To save the cellulitis patient from a painful and unnecessary procedure (I&D)
C) To prevent providing an ineffective treatment to the abscess patient (antibiotics alone)
D) You may save the life of a necrotizing fasciitis patient.
E) All of the above are great reasons to use ultrasound to evaluate soft tissue infections

(Answers: 1. e, 2. c, 3. c, 4. b, 5. e )

The Winner

Congratulations to Sooyeon Kim our winner of the Case of the Month! Enjoy your Starbucks winnings!!


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