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.
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.
Reference
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
.