An ultrasound test uses high-frequency sound waves to create images of internal organs or tissues. It works by sending low-energy sound waves against tissue. Some waves pass through and some are reflected (bounce back). As sound waves bounce back, they are recorded and displayed on a computer screen or television-type monitor.

The image created by an ultrasound is considered to be less clear than those obtained by using computed axial tomography (CAT scan) or magnetic resonance imaging (MRI). However, ultrasound is commonly used for a wide array of diagnostic studies since it is fast, generally noninvasive and relatively inexpensive. 

Ultrasound technology can help a physician diagnose and monitor the progress of various obstetric and gynecological conditions. These include:

• Pregnancy and pregnancy-related conditions
  

  

• Breast cancer and gynecological cancers, such as those of the ovaries, cervix, endometrium or vagina
  
  
• Measurement of follicular growth in fertility treatments
  
  
• Other conditions, such as dysfunctional uterine bleeding (DUB), uterine fibroids, polycystic ovarian syndrome (PCOS) and urinary system disorders

Ultrasound can also be used to help guide needles and other instruments under the skin and to the proper organ or body area.