(Breast Ultrasonography, Breast Sonogram, Mammographic Ultrasound, Sonomammography, Ultrasound Mammography)
What is breast ultrasound?
Breast ultrasound is a noninvasive (the skin is not pierced) procedure used to assess the breasts. Ultrasound technology allows quick visualization of the breast tissue. Ultrasound may also be used to assess blood flow to areas inside the breasts. The examination is often used along with mammography.
Breast ultrasound uses a handheld probe called a transducer that sends out ultrasonic sound waves at a frequency too high to be heard. When the transducer is placed on the breast at certain locations and angles, the ultrasonic sound waves move through the skin and other breast tissues. The sound waves bounce off the tissues like an echo and return to the transducer. The transducer picks up the reflected waves, which are then converted into an electronic picture of the breasts.
Different types of body tissues affect the speed at which sound waves travel. Sound travels the fastest through bone tissue, and moves most slowly through air. The speed at which the sound waves are returned to the transducer, as well as how much of the sound wave returns, is translated by the transducer as different types of tissue.
Prior to the procedure, clear, water-based gel is applied to the skin to allow for smooth movement of the transducer over the skin and to eliminate air between the skin and the transducer.
By using an additional mode of ultrasound technology during an ultrasound procedure, blood flow within the breast can be assessed. An ultrasound transducer capable of assessing blood flow contains a Doppler probe. The Doppler probe within the transducer evaluates the velocity and direction of blood flow in the vessel by making the sound waves audible. The degree of loudness of the audible sound waves indicates the rate of blood flow within a blood vessel. Absence or faintness of these sounds may indicate an obstruction of blood flow.
Ultrasound may be safely used during pregnancy or in the presence of allergies to contrast dye, because no radiation or contrast dyes are used.
More recent ultrasound technologies, such as three-dimensional (3D) and four-dimensional (4D) ultrasound, tissue harmonic imaging (uses the harmonic signal generated by tissue itself), ultrasound contrast agents, and ultrasound elastography (low-frequency vibration technique used to evaluate movement of breast lesions), show promise for diagnosing cancerous breast lesions in a noninvasive manner.
Related procedures that may be performed to evaluate breast problems include mammography, breast biopsy, and breast scan. Please see these procedures for more information.
Anatomy of the breasts
Each breast has 15 to 20 sections, called lobes, which are arranged like the petals of a daisy. Each lobe has many smaller lobules, which end in dozens of tiny bulbs that can produce milk.
The lobes, lobules, and bulbs are all linked by thin tubes called ducts. These ducts lead to the nipple in the center of a dark area of skin called the areola. Fat fills the spaces between lobules and ducts.
There are no muscles in the breast, but muscles lie under each breast and cover the ribs.
Each breast also contains blood vessels and vessels that carry lymph. The lymph vessels lead to small bean-shaped organs called lymph nodes, clusters of which are found under the arm, above the collarbone, and in the chest, as well as in many other parts of the body.
Reasons for the procedure
A breast ultrasound procedure is commonly performed to determine if an abnormality detected by mammography or a palpable lump is a fluid-filled cyst or a solid tumor (benign or malignant). Breast ultrasound may also be used to identify masses in women whose breast tissue is too dense to be measured accurately by mammography. Breast ultrasound is generally not used as a screening tool for breast cancer detection because it does not always detect some early signs of cancer such as microcalcifications, which are tiny calcium deposits.
Ultrasound may be used in women for whom radiation is contraindicated, such as pregnant women, women younger than 25 years, and women with silicone breast implants. The procedure may also be used to guide interventional procedures such as needle localization during breast biopsies and cyst aspiration (removal of fluid from cyst).
There may be other reasons for your physician to recommend breast ultrasound.
Risks of the procedure
Unlike mammography, breast ultrasound does not use radiation, and therefore poses no risk to pregnant women.
Breast ultrasound may miss small lumps or solid tumors that are commonly detected with mammography.
There may be other risks depending on your specific medical condition. Be sure to discuss any concerns with your physician prior to the procedure.
Obesity and excessively large breasts may interfere with breast ultrasound.
Before the procedure
Your physician will explain the procedure to you and offer you the opportunity to ask any questions that you might have about the procedure.
If an invasive procedure such as a needle biopsy is to be done during the breast ultrasound, you may be asked to sign a consent form that gives permission to do the procedure. Read the form carefully and ask questions if something is not clear.
No fasting or sedation is required before the procedure.
You should not apply any lotions, powder, or other substances to the breasts on the day of the procedure.
Dress in clothes that permit access to the area to be tested or that are easily removed.
Based upon your medical condition, your physician may request other specific preparation.
During the procedure
Breast ultrasound may be performed on an outpatient basis or as part of your stay in a hospital. Procedures may vary depending on your condition and your physician's practices.
Generally, breast ultrasound follows this process:
You will be asked to remove any jewelry and clothing from the waist up and will be given a gown to wear.
You will be asked to lie on your back on an examination table and raise your arm above your head on the side of the breast to be examined. Alternatively, you may be positioned on your side.
A conductive paste or gel will be applied to the breast(s), and a hand-held transducer will be placed directly on the skin overlying the breast.
After the procedure is completed, the gel will be removed from the breast(s).
After the procedure
Generally, there is no special care following a breast ultrasound. However, your physician may give you additional or alternate instructions after the procedure, depending on your particular situation.