why is safe to use ultrasound with water?

Answer 1

Ultrasound is sonography...based on sonar! Sonar is sound waves used to detect things under water. So, an ultrasound, being based on sonar technology, requires water for the sound waves to work. Water imposes no danger to sonar...in fact, sonar (hence ultrasound) has to have it to work.

BTW, sonar comes in two forms: infrasonic and ultrasonic. Ultrasonic is a sound frequency higher than our hearing's upper limit.

Answer 2

in the area of women's health, it is usually the practice to encourage women to have a full bladder to look at your gynaec organs through the ultrasound images.

Water or fluid i.e. urine in the urinary bladder serves as a good medium through which to send the sound waves and then get them reflected through your body parts i.e. the gynaecological organs and thus see those image on a screen.

This is the reason, why people undergoing pelvic ultransonogram are encouraged to come full bladder.

Likewise, while doing an ultrasound of your pancreas, water in the stomach gives a good medium through which to look at the pancreas, which is located at the greater curvature and the C shaped part of the stomach and duodenum junction.

Hope this answers your question