A breast ultrasound is a painless imaging exam that typically takes 15 minutes or less. A technologist applies gel to your breast and moves a small handheld device across the skin, which sends sound waves into the tissue and captures images in real time on a screen. There’s no radiation involved, and no compression like a mammogram.
Why You Might Need One
Breast ultrasounds are most commonly ordered to investigate a lump you or your doctor felt during an exam, or to get a closer look at something that appeared on a mammogram. They’re especially useful for people with dense breast tissue. Dense tissue shows up white on a mammogram, and so do potential tumors, making it difficult to distinguish one from the other. Ultrasound uses a completely different imaging method, so it can often tell apart a solid mass from a fluid-filled cyst that a mammogram can’t characterize well.
Your doctor may also order one if you have breast pain in a specific area, nipple discharge, or skin changes. It’s sometimes used as a supplemental screening tool alongside mammography for people at higher risk of breast cancer.
How to Prepare
Preparation is minimal. On the day of your exam, skip lotion, powder, and deodorant, as these products can interfere with the ultrasound image. Remove any jewelry from your neck and chest area before the exam begins. Wearing a two-piece outfit makes things easier since you’ll only need to undress from the waist up. You don’t need to fast or stop any medications beforehand.
What Happens During the Exam
You’ll change into a gown and lie on your back on an exam table, usually with one arm raised above your head. The technologist or radiologist applies a clear, water-based gel to the breast being examined. The gel eliminates air between your skin and the transducer (the handheld device), which helps the sound waves travel more efficiently into the tissue.
The transducer is then pressed gently against your skin and moved slowly across the breast in a systematic pattern. Inside the device, tiny crystals vibrate when an electrical current hits them, sending high-frequency sound waves into your breast. Those waves bounce off the different tissue layers, fat, glands, ducts, and any masses, then return to the transducer, which translates the echoes into a grayscale image on a monitor. Dense structures like solid masses reflect sound waves differently than fluid-filled cysts, which is how the radiologist can tell them apart.
The technologist will typically image the breast from three to four different positions, adjusting the angle and pressure slightly to capture views of all areas. If you came in because of a specific lump or area of concern, the technologist will spend extra time on that region. You may feel light to moderate pressure as the transducer is pressed against your skin, but the exam should not be painful. The contrast with mammography is significant: mammograms require firm breast compression between two plates, and between 25% and 46% of women report enough discomfort that it discourages them from returning for their next screening. Ultrasound involves none of that compression.
Most exams wrap up in under 15 minutes. A more thorough bilateral exam covering both breasts in detail can take 20 to 25 minutes.
What Your Results Mean
A radiologist reviews your images and assigns a standardized score called a BI-RADS category, which ranges from 0 to 4 (and higher). Here’s what each one means in practical terms:
- Category 0: The images were incomplete or unclear, and you’ll need additional imaging before the radiologist can make an assessment.
- Category 1: Negative. No abnormalities found.
- Category 2: Also negative, but some clearly benign findings were noted, like simple cysts. Routine screening continues on your normal schedule.
- Category 3: Probably benign, with roughly a 2% chance the finding is cancerous. Your doctor will typically recommend a follow-up ultrasound in six months to confirm nothing has changed.
- Category 4: A suspicious abnormality was found, and a biopsy is recommended. This category is further divided: 4A means a 2% to 10% likelihood of cancer, while 4B means a 10% to 50% likelihood.
How quickly you get results varies. Some imaging centers now aim to deliver normal results within 10 minutes of the exam. Others send a report to your referring doctor within a few business days, who then contacts you.
If a Biopsy Is Needed
When ultrasound reveals something suspicious, the next step is usually an ultrasound-guided biopsy. In some facilities, this can happen the same day, sometimes within an hour of your initial scan. During the biopsy, a radiologist uses the same ultrasound technology to watch a needle on screen as it’s guided precisely to the area of concern. A small tissue sample is removed and sent to a lab for analysis. The ultrasound guidance makes the procedure more accurate and less invasive than surgical biopsies. You’re awake the entire time, with local numbing applied to the biopsy site.
Biopsy results typically come back within a few days to a week, depending on the lab. Most biopsied findings turn out to be benign, particularly those in the lower BI-RADS subcategories.