Before your sonographer begins the scan, they will apply a warm lubricating substance to the area of interest. This substance is known as ultrasound transmission gel.
During your imaging exam, the ultrasound probe is pushed against this gel to help capture medical images. The gel used is hypoallergenic, non-irritating, and non-sensitizing, so you are unlikely to have a reaction.
The way in which ultrasound transmission gel operates is by reducing the acoustic impedance and conducting the sound waves between the probe and your body. Ultimately, the ultrasound transmission gel creates a bridge between the probe and your tissue, allowing for clear transmission of medical images during your exam.