Sound: Mechanical vibrations transmitted through an elastic medium. Waves are comprised of compressions (high pressure areas) and rarefactions (low pressure areas). Sound waves transfer energy from the source to the receiver. Sound waves travel at a set velocity which is determined by the medium.

 
 
   
 
   

Sounds are transmitted in frequencies. Frequency means how often something happens. We measure in Low and High sound frequencies. Lower frequencies of sound travel longer distances. Example: The bass on a car radio can be heard from far away even though the sound is muffled. Higher frequencies of sound travel shorter distances.

Example: A high pitched sound from a dinner bell can only be heard within close range, even though the sound is clear. Ultrasound frequencies are measured in number of cycles per second.

    
   
 
 
 
   
Abdominal imaging: A low frequency transducer (3-5 MHz) penetrates deeper but the resolution is compromised.
Transvaginal imaging: A high frequency transducer (7-10 MHz) allows for superficial imaging but provides optimal resolution.
Abdominal ultrasound should be performed once the patient has a full bladder
Transvaginal ultrasound should be performed once the patient’s bladder is empty.