Overview

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:

• Doppler is a special type of ultrasound that creates images of blood flow through vessels.
• Bone sonography helps doctors diagnose osteoporosis.
• Echocardiograms are used to view the heart.
• 3D imaging adds another dimension to the ultrasound image, creating three-dimensional interpretations rather than the flat two-dimensional images that are made with traditional ultrasound.

Why Is Ultrasound Needed?

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:

• heart valve problems, such as mitral valve prolapse or aortic stenosis;
• congestive heart failure;
• blood clots due to irregular heart beats such as in atrial fibrillation;
• abnormal fluid collections around the heart, such as pericardial effusions; and
• pulmonary artery hypertension.

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:

• carotid ultrasound
• abdominal aorta ultrasound for abdominal aortic aneurysm
• blood clots in veins (superficial or deep venous thrombosis, or DVT).
• an ultrasound scan can reveal whether a lump is a tumor. This could be cancerous, or a fluid-filled cyst.

Abdominal Structures

Abdominal ultrasound is used to evaluate the solid organs within the abdominal cavity, including the liver, gallbladder, pancreas, kidneys, and bladder.

• Renal ultrasound is used to evaluate the function and structure of the kidneys. Swelling around the kidney with blockage in the urinary tract can be seen with ultrasound, making abdominal ultrasound useful in detecting kidney stones
• Liver ultrasound is used to find abnormalities in the liver tissue and ducts.
• Gallbladder ultrasound can screen for gallstones or an infected gallbladder.
• Appendix ultrasound is used in children or pregnant women, where it is necessary to avoid radiation from aCT scan (computerized tomography).
• Testicular ultrasound: Used to diagnose testicular torsion, epididymitis (testicle infection), and testicular masses.

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.

Procedure

• Most scans take between 20 and 60 minutes. It is not normally painful, and there is no noise.
• In most cases, no special preparation is needed, but patients may wish to wear loose-fitting and comfortable clothing.
• If the liver or gallbladder is affected, the patient may have to fast, or eat nothing, for several hours before the procedure.
• For a scan during pregnancy, and especially early pregnancy, the patient should drink plenty of water and try to avoid urinating for some time before the test.
• When the bladder is full, the scan produces a better image of the uterus.
• The scan usually takes place in the radiology department of a hospital. A doctor or a specially-trained sonographer will carry out the test.
• Wear loose or comfortable clothes.
• Remove all jewelries in the area where ultrasound is to be done.
• It’s a non-invasive painless procedure that is expected to be very safe.