HPI: 21 yo male with no PMH presenting for bump noted in the gluteal cleft x 3 days.
The linear probe was placed on the area of interest and showed:
Dot-dash sign/pattern are hyperechoic lines and dots that represent hair. This is commonly seen in ovarian dermoid cysts but also can be seen in pilonidal abscesses from ingrown hair!
Also look carefully at the left side of the screen at the end of the attached video. You might notice the echogenic contents moving around internally as pressure is applied with the probe- this is “squish/swirl sign” AKA “pus-talsis” which is another sign you are looking at an abscess rather than a mass.
As a review of abscesses, you will generally see:
A fluid filled irregularly shaped structure with internal septations or echogenic debris (vs a cyst will be contained and completely anechoic)
Squish/swirl sign
Posterior acoustic enhancement
Surrounding tissue cellulitis (early sign: dermal thickening with hyperechoic subcutaneous layer and later sign: “cobblestoning” or edema between fat globules)
Case conclusion: Patient had a bedside I&D of his pilonidal abscess with purulent materials expressed.
Happy scanning!
The US Team
Learn more:
https://www.pocus101.com/gynecology-pelvic-ultrasound-made-easy-step-by-step-guide/
https://www.acep.org/sonoguide/procedures/abscess-evaluation