Ultrasound (also termed sonography, ultrasonography, and Doppler study) is a non-invasive diagnostic medical imaging technique that uses high frequency sound waves to produce images (sonogram) of organs and structures inside the body. Health care professionals use it to view the heart, blood vessels, kidneys, liver, and other organs. During pregnancy, doctors use ultrasound to view the fetus. Unlike x-rays, ultrasound does not expose you to radiation.
Using an ultrasound machine (ultrasonography), a technician or doctor moves a device called a transducer or wand (probe) over part of your body. The transducer emits sound waves which bounce off the internal tissues, and creates images from the waves that bounce back. Different densities of tissues, fluid, and air inside the body produce different images that can be interpreted by a physician, typically a radiologist (a physician who specializes in imaging technologies). Many studies are done by a trained technologist (sonographer) and then interpreted by a radiologist.
Moreover, ultrasound technology has advanced to allow for different types of imaging:
Obstetrics: Pregnancy ultrasound (fetal ultrasound or baby ultrasound) is used to assess the progression of a fetus. It is used to find out the number of fetuses in the womb, the age of the fetus, the location of the placenta, the fetal position, movement, breathing and heart rates, and the amount of amniotic fluid in the uterus. Most women have at least one ultrasound during pregnancy. The exams can be done trans-vaginally (early in a pregnancy), but most are done trans-abdominally. 3D and 4D ultrasound have limited medical uses, such as when a specific problem is suspected. Currently 3D and 4D ultrasounds are popular for “keepsake” sonogram pictures of the baby in the womb. The best time for a 3D ultrasound for fetal photos is when the baby is about 26 weeks. The FDA warns against the use of ultrasound for nonmedical reasons. Although there has been no proof of risk, the long-term effects of these ultrasounds have not been studied. Doppler ultrasounds are used to measure blood flow and may be used if there is a suspicion that the fetus is not growing properly.
Gynecology: Vaginal ultrasound, pelvic ultrasound, or transvaginal ultrasound is used to diagnose growths or tumors of the ovary, uterus, and Fallopian tubes. It can be used to assess non-pregnancy related issues as well:
Cardiology: Echocardiography (heart ultrasound) is a common way to evaluate the overall function of the heart. It is used to evaluate the flow of blood through the chambers and valves of the heart. It also assesses the strength of the heart beat and the volume of blood pumped through. Doppler ultrasound echocardiography is often used for the following:
Blood vessels: Ultrasound is useful in detecting problems with most of the larger blood vessels in the body. Using Doppler ultrasound technology, the flow of blood through the vessels can be observed and measured. Narrowing of vessels (stenosis) or widening of vessels (dilatation, also referred to as aneurysms) can be detected. Ultrasound testing of blood vessels includes:
Abdominal structures: Abdominal ultrasound is used to evaluate the solid organs within the abdominal cavity, including the liver, gallbladder, pancreas, kidneys, and bladder.
Neck ultrasound: The thyroid and parathyroid glands can be imaged to detect nodules, growths, and tumors.
Breast ultrasound: Used to image the breasts and to guide biopsy of breast masses in order to evaluate for breast cancer.
Knee ultrasound: Ultrasound can be used to evaluate the structures in the back of the knee to determine if a Baker’s cyst is present.
Eye ultrasound: An eye ultrasound is used to look at the back of the eye (retina). It is often used when a patient hascataracts that make looking into the eye difficult. The test may help diagnose retinal detachment. It can also assist in cataract surgery.
Skin ultrasound: Ultrasound can be used to help find certain types of foreign bodies that may become lodged in the skin.
Musculoskeletal ultrasound: It can help diagnose problems with soft tissues, muscles, blood vessels, tendons, and joints. It is used to investigate a frozen shoulder, tennis elbow, carpal tunnel syndrome, and others.