| Ultrasound-Guided Breast Biopsy
What is Ultrasound-Guided Breast Biopsy? Back to Top
Ultrasound
is an excellent way to evaluate breast abnormalities detected by
mammography, the patient or her doctor, but in some cases it is not
possible to tell from the imaging studies alone whether a growth is
benign or cancerous. Ultrasound-guided breast biopsy is a highly
accurate way to evaluate suspicious masses within the breast that are
visible on ultrasound, whether or not they can be felt on breast
self-examination or clinical examination. The procedure prevents the
need to remove tissue surgically and also eliminates the radiation
exposure that comes from using x-rays to locate a mass. After placing
an ultrasound probe over the site of the breast lump and using local
anesthesia, the radiologist guides a biopsy needle directly into the
mass. Tissue specimens are then taken using either an automatic
spring-loaded or vacuum-assisted device (VAD).
What are some common uses of the procedure? Back to Top
Ultrasound
is most often used to guide breast biopsy when a breast abnormality is
visible on ultrasound. It may be performed with either a large hollow
needle (automated core breast biopsy) or a vacuum-powered instrument.
When it is necessary to do an open surgical biopsy, a guide wire first
is passed directly into the mass. This procedure also may be guided by
ultrasound.
Ultrasound-guided biopsy is most useful when there are suspicious
changes on the mammogram that can also be seen on an ultrasound exam
but no abnormality can be felt on breast self-examination or clinical
examination by your primary care physician. However, there are times
when your doctor decides that ultrasound guidance for biopsy is
appropriate even for a mass that can be felt.
How should I prepare for the procedure? Back to Top
Although
ultrasound-guided breast biopsy is minimally invasive there is a risk
of bleeding whenever the skin is penetrated. For this reason if you are
taking aspirin or a blood thinner your physician may advise you to stop
three days before the procedure. A breast biopsy always raises concern
about cancer. You may want to have a relative or friend come with you
to lend support and also to drive you home afterward.
What does the equipment look like? Back to Top
Before the
radiologist arrives to do the biopsy, staff will set up sterile
materials, including syringes, local anesthetic, sponges, forceps,
scalpels and a specimen cup. The radiologist holds an ultrasound device
in one hand while using the other to guide the needle into the lesion.
How does the procedure work? Back to Top
Ultrasonography
uses sound waves at very high frequency to image internal structures,
including those deep within the body. Either pulsed or continuous sound
waves are directed at the area of interest using a hand-held device
called a transducer. The transducer also receives echoes of the sound
waves in a pattern that reflects the outlines of the internal structure
mass. The transducer changes electrical signals into ultrasound waves
and converts the reflected sound waves back to electrical energy.
Unlike radiological procedures, the ultrasound method requires no
exposure to x-rays.
When ultrasound is chosen to guide a breast biopsy, one of the
biopsy instruments used is a VAD. Nodules of tissue less than about an
inch in size can be totally removed using this equipment. These systems
use vacuum pressure to pull tissue into a needle and remove it without
having to withdraw the probe after each sampling—as is necessary when
the core needle method is used. Biopsies are obtained in an orderly
manner by rotating the needle, ensuring that the entire region of
interest will be sampled.
The core needle method is used most commonly because it is the least
expensive, easy to perform and highly accurate for many lesions. An
inner needle with a trough extending from it at one end is covered by a
sheath and attached to a spring-loaded mechanism. When the mechanism is
activated, the needle moves forward, filling the trough with breast
tissue. The outer sheath instantly moves forward to cut the tissue and
keep it in the trough. It takes only a fraction of a second to obtain a
sample and for each sample it is necessary to withdraw the needle to
collect the tissue.
How is the procedure performed? Back to Top
With the patient
lying on her back or turned slightly to the side, the ultrasound probe
is used to locate the lesion. Enough local anesthesia is injected to be
sure that she will feel no discomfort during the procedure. Ultrasound
also is used to guide the injection of anesthetic along the route to
the lesion and about the mass. A very small nick is made in the skin at
the site where the biopsy needle is to be inserted. The radiologist,
constantly monitoring the lesion site with the ultrasound probe, guides
a hollowcore biopsy needle or the vacuum-assisted needle directly into
the mass and obtains specimens. Usually at least four samples are
taken. In some cases it may be difficult to visualize the needle in the
breast tissue and considerable skill is needed to coordinate movements
of the ultrasound transducer with needle insertion. If the lesion is
nearly or completely removed during the biopsy procedure, a clip is
placed where the lesion was located to ensure that the site can be
easily located for additional surgery if the lesion proves to be
malignant.
What will I experience during the procedure? Back to Top
You
will be awake during your biopsy and should have little or no
discomfort. Generally the biopsy is completed in less than an hour. It
is not necessary to close the tiny skin incision with sutures; a small
compression dressing will do. Most patients are able to resume their
usual activities later the same day.
Who interprets the results and how do I get them? Back to Top
The
pathologist will examine the tissue specimens after they are processed.
A definite diagnosis will be available within a few days, the main
question being whether the breast mass is benign or cancerous. When the
final biopsy findings are available you may have a session with your
physician to discuss the results and decide together on the next step.
If cancer is diagnosed you probably will be referred to a tumor
specialist or surgeon.
What are the benefits vs. risks? Back to Top
Benefits
- Ultrasound-guided breast biopsy reliably provides tissue
samples that can show whether a breast lump is benign or malignant.
When using the VAD it may be possible to remove the entire lesion.
- Ultrasound-guided
core biopsy, using either the core method or the VAD, takes much less
time than surgical biopsy, causes less tissue damage and is far less
costly.
- Compared with x-ray or stereotactically
guided breast biopsy, the ultrasound method is faster and avoids the
need for ionizing radiation exposure. With ultrasound it is possible to
follow the motion of the biopsy needle as it takes place.
- Ultrasound-guided
breast biopsy is able to evaluate lumps under the arm or near the chest
wall, which are hard to assess by the x-ray-guided (stereotactic)
method.
- Ultrasound-guided biopsy is somewhat less expensive than the x-ray-guided (stereotactic) method.
Risks
- When the VAD is used for ultrasound-guided breast biopsy,
large pieces of tissue are removed and there is a risk of bleeding and
formation of a hematoma, a collection of blood at the biopsy site. The
risk, however, appears to be less than 1 percent of patients.
- An occasional patient has significant discomfort, which can be readily controlled by non-prescription pain medication.
- Infection
can occur whenever the skin is penetrated, but the chance of infection
requiring antibiotic therapy is less than one in 1,000.
- Doing
a biopsy of tissue deep in the breast carries a slight risk that the
needle will pass through the chest wall, allowing air around the lung
that could collapse a lung. This is a rare occurrence.
What are the limitations of Ultrasound-Guided Breast Biopsy? Back to Top
Like
x-ray-guided breast biopsy, ultrasound-guided biopsy occasionally will
miss a lesion or underestimate the extent of disease. If the diagnosis
remains uncertain after a technically successful procedure, surgical
biopsy will be necessary. The ultrasound-guided method cannot be used
unless the mass can be seen on an ultrasound exam. Calcifications
within a cancerous nodule are not shown as clearly by this approach as
when x-rays are used.
Small lesions may be difficult to target accurately by ultrasound-guided core biopsy. Back to Top |
