What is the gel stuff that they put on a pregnant belly before have an ultrasound?

The gel that is applied to a pregnant belly before an ultrasound is called ultrasound gel. It is a water-based gel that helps to create a smooth surface between the ultrasound probe and the skin, allowing for better transmission of sound waves. Ultrasound gel also helps to reduce air pockets between the probe and the skin, which can interfere with the ultrasound images.