There are various techniques of ultrasound imaging, including:

• A-mode, or amplitude modulation, which is recorded as a single line showing the time needed to reach the organ and return to the transducer, a small device that sends ultrasound waves through the body.
  
  
• B-mode, which is brightness modulation
  
  
• Gray scale, which shows the texture of various organs in shades of white and gray
  
  
• Real-time imaging, which shows rapid multiple views of tissues in motion
  
  
• Doppler imaging, which shows increased blood vessels within a mass of tissue
  
  
• Echocardiogram, which shows heart anatomy and function

Some of the most common obstetric and gynecological ultrasound tests include:

• Abdominal ultrasound. Used to view the kidneys, pancreas, gallbladder, pelvis and other internal organs in the abdomen area. A technique used in fertility assessment involves filling the uterus with a saline solution before performing an ultrasound (sonohysterography) in order to view the uterine cavity and fallopian tubes.
  
  
• Pregnancy ultrasound. Used to check the development of the fetus, including the baby’s heartbeat, size, location and, sometimes gender. If congenital heart defects are suspected in a fetus, a fetal echocardiogram may be performed.
  
  
• Transvaginal ultrasound. Uses a higher frequency of sound than an abdominal ultrasound, which enhances the detail but limits the area that can be viewed. It is used to view the ovaries and uterus and to confirm a pregnancy early in the first trimester. It can also determine an ectopic pregnancy  or molar pregnancy or the viability of a pregnancy when a woman is experiencing bleeding. Transvaginal ultrasounds involve placing an imaging tool similar to a wand in the vagina to view the internal organs and tissues.
  
  
• Breast ultrasound. Used to provide a closer look at a possible breast mass. It can be performed in addition to a mammogram to help determine if a mass is fluid or solid. Breast ultrasound can also be used to determine if a breast implant has ruptured.
  
  
• Interventional ultrasound. Used to a guide a surgeon during a minimally invasive procedure, such as in the placement of needles during a breast biopsy or the drainage of infections.
  
  
• Renal ultrasound. Used to view the kidneys and the rest of the urinary tract.