What exactly is an ultrasound, anyway? How does an ultrasound work? And why does my doctor want me to have one? Here is a handy guide on the what, how, and why of this common screening device.
First of all, every woman should know that it's perfectly natural to be scared when everything doesn't go, "as usual" with your annual mammogram. About 10 to 15 percent of all screening mammograms result in a "callback," -- i.e., the need for a further mammogram. And about 95 percent of callbacks end right there, with no further screening necessary.
The further screening can help specialists take a closer look at something to ensure accuracy of the result. The radiologist might have seen a piece of breast tissue folded over on itself, regular glandular tissue viewed from an odd angle, or something else that, with another, different mammogram, looks just fine.
But sometimes, even after a second view, something doesn't look quite right. At that point, the radiologist may order an ultrasound, a.k.a., sonogram. This callback does not necessarily mean that the patient has cancer — or, in many cases, that the patient has anything to be concerned about. The vast majority of breast lumps, or "abnormalities" seen on mammograms, are NOT cancer. Even if the ultrasound were to prove inconclusive and you needed a biopsy, about 85 percent of biopsies are negative; no cancer. So odds are your ultrasound will show that what the radiologist saw is, in fact, not cancer at all.
But the ultrasound's main advantage over mammograms is that it's very good at showing whether a lump or mass is solid, or filled with fluid. A solid lump needs further examination, either via MRI, or biopsy. But if the lump is filled with fluid, your testing is done: the lump is a cyst.
Cysts (and accompanying fibrocystic change) are quite prevalent in women under the age of 50. In fact, the most common cause of non-cancerous breast lumps in women between the ages of 30 and 50 is cysts. On an ultrasound, a cyst is dark black outlined in white; it's very distinctive, and easily identified.
An ultrasound might also show a plugged milk duct, or a fat lobule — other conditions mammograms are unable to distinguish from regular breast tissue.
The test itself
An ultrasound can take 20 to 30 minutes, but it's an easy test. You'll lie on a table with your arm above your head, and the person performing the ultrasound (the sonographer) will rub a clear, water-based gel on your breast; sometimes it feels uncomfortably cold for a minute, but it warms up fast.
The sonographer will then run a small device, called a transducer, over the area of your breast with the lump. The gel helps the transducer maintain contact with your skin. The transducer sends images to a computer screen, which the sonographer watches as s/he works. Since this is all done in real time, s/he can easily adjust the area being scanned to view the lump from different angles.
Unlike radiation-based mammograms, an ultrasound uses high-frequency sound waves to "see" tissue in the breast. These sound waves bounce back at different rates, depending on what they strike; and a computer interprets the information and turns it into a visual image.
Sometimes the sonographer or doctor will want to review the images, and you may be asked to wait. Other times, it's clear right away that what you have is a cyst; and at the end of the exam you can simply wipe the gel off, get dressed, and go home. You shouldn't experience any after-effects at all, and can go back to your usual activities right away.
After the ultrasound
If you have a cyst, then there's no need for any follow-up — unless the cyst is particularly large and/or painful, in which case your doctor may choose to drain it.
If the ultrasound shows that the lump or mass is solid, then the screening process will continue, either with an MRI, which is more sensitive than mammography and can show a more complete, detailed image of any solid mass, or with a biopsy.
'Dense breasts,' ultrasound, and mammograms
Some women have a clinical condition commonly known as "dense breasts," The term refers to breasts that have very little fat, compared to the glands and connective tissue in the breast. And while fat shows up clear on an X-ray (mammogram), other tissue — including tumors — shows up opaque. Thus it's much easier for tumors to "hide" in dense breasts than in normal breasts.
So, can women with dense breasts skip the mammogram, and just rely on ultrasound for their regular screening? Well, not exactly. Ultrasounds can't pick up the tiniest tumors or pre-cancerous microcalcifications that a mammogram can spot. The best choice for these women is a mammogram combined with ultrasound, which is about 50 percent more effective at spotting possible tumors in dense breasts than a mammogram alone.
Since women with dense breasts also have a very slightly increased risk of breast cancer, most doctors will be proactive in selecting the best combination of screening processes possible for those patients. Women with "normal" breasts, meanwhile, derive no extra benefit from the ultrasound/mammogram combination, compared to mammogram alone, and thus do not require an ultrasound along with their annual mammogram.
Updated on: May 10, 2016
Published On: November 01, 2010