I’ve heard of underwater basketweaving, but underwater ultrasonography?

Bedside ultrasonography is a great tool to help find small foreign bodies. Commonly foreign bodies get lodged superficially in the patient’s extremities. Because superficial structures (<1 cm deep) are difficult to visualize on ultrasound, you should apply a really generous, thick layer of ultrasound gel to create some distance. Alternatively, you can add a step-off pad, such as a bag of saline or fluid-filled glove, to place between the patient’s skin and transducer. What’s a quicker and easier way to create some distance yet preserve image quality?

Trick of the Trade

Submerse both the body part and the ultrasound transducer under water.

ultrasonography water bath

For this “bath water technique”, start by holding the transducer perpendicular to the wound and about 1 cm away from the skin. You can adjust the distance to optimize the image quality.



Thanks to Andy at Emergency Medicine Ireland blog for these 2 ultrasound images! 

This submersion technique has been published in American Journal of EM in 2004 as a painless alternative to gel or a step-off pad, because the transducer does not need to apply any pressure on the patient’s wound.

Blaivas M, Lyon M, Brannam L, Duggal S, Sierzenski P. Water bath evaluation technique for emergency ultrasound of painful superficial structures. Amer J Emerg Med. 2004; 22(7), 589-93 PMID: 15666267

Michelle Lin, MD
ALiEM Founder and CEO
Professor and Digital Innovation Lab Director
Department of Emergency Medicine
University of California, San Francisco
Michelle Lin, MD


Professor of Emerg Med at UCSF-Zuckerberg SF General. ALiEM Founder @aliemteam #PostitPearls at Bio:
Michelle Lin, MD