J. Taylor Whaley, MD
The Abramson Cancer Center of the University of Pennsylvania
Last Modified: March 21, 2012
What is a stereotactic needle biopsy?
A stereotactic biopsy, also known as a stereotactic core needle biopsy, is an outpatient procedure to obtain a tissue sample of a suspicious lesion, or abnormality seen on a radiology scan but difficult to feel on physical exam.
Stereotactic biopsies are most frequently used for breast biopsies but are also used to evaluate lung, liver, and brain abnormalities.
Because imaging and radiology tests have improved dramatically, very small lesions are frequently discovered. Unfortunately, it is often very difficult to know whether the abnormality is benign or cancerous, and it is very important to remember that just because something is abnormal, it does not mean it is bad. The majority of abnormalities seen on radiology tests turn out to be benign findings; however, these lesions are often too small or too deep to be felt by exam. For this reason, image-guidance is frequently employed when the suspected lesion is too small.
Stereotactic biopsies are outpatient procedures, minimally invasive, well tolerated, and widely available throughout the U.S. and most developed countries.
How is this test performed?
A stereotactic biopsy is performed to follow up on an abnormality discovered on a scan. These biopsies are generally performed under local anesthesia (using a numbing medicine). For most of these procedures, a radiologist will be the doctor performing the biopsy.
If a lesion can be felt, it may be located and biopsied using palpation (touching or compression with fingers). If the lesion is small and not palpable, a stereotactic biopsy will be requested. Stereotactic means the biopsy is done using X-rays or a CT scan to locate the lesion and ensure the needle is placed directly into the abnormal area. Using X-rays oriented at different angles, a 3-D image can be created to aid the radiologist in isolating the area of interest.
For breast biopsies, a mammogram is used for image guidance. This often occurs after calcifications are seen with a screening mammogram. You will generally be lying or sitting during the test. After the area is located, a very small needle is used to numb the area (often with lidocaine). A core needle will be inserted at the area of interest. This needle has a hollow middle, which can collect cells in their natural state, with surrounding cells attached. The hollow needle is normally passed through the lesion several times to make sure enough tissue is obtained.
For lung or liver lesions, a CT scan may be used as the imaging technique to locate the area. Similar to X-rays, CT scans help create a 3-D image for the radiologist to locate the abnormality.
After the tissue is collected, the sample is placed onto a glass slide for a pathologist to evaluate. A pathologist is a doctor that specializes in looking at tissues under the microscope. After the pathologist has established a diagnosis, a report is generated for your doctor.
The actual insertion of the needle takes only a few minutes and the whole procedure can take 30 minutes to an hour.
Similar to any biopsy, the most important risk associated with a stereotactic biopsy is bleeding. Generally, there is very little bleeding associated with the procedure, although rarely, a hematoma, or a pocket of blood, will collect at the site of the biopsy. This can be slightly uncomfortable but should resolve over the next few days. If there is severe pain following the procedure, you should contact your doctor immediately.
Additionally, there is always a risk of infection and you should call your doctor if you develop fevers or the area becomes red / inflamed. If you undergo a stereotactic lung biopsy, there is a risk of collapse of the lung, which your doctor will look for after the procedure is done.
How do I prepare for a stereotactic biopsy?
Frequently, no preparation is needed; however, if you are on blood thinners, your doctor will likely have you stop them several days in advance. This should be discussed when the biopsy is scheduled.
How do I interpret the results of a pathology report?
Following the biopsy, the tissue sample is processed by a pathologist. A preliminary report may be given to the doctor; however, the final report generally takes several days.
The report generally states the patient's name, date of birth, site of biopsy, and indication (reason for the test) at the top of the report. Pathology reports follow a standard outline, regardless where they are obtained. The findings are discussed in a very systematic approach. For this reason, it is very important to discuss the results with your doctor.
The first paragraph typically reports the final diagnosis. This is a summary of the findings, often generated to answer the question posed by the ordering physician. If the biopsy is obtained for oncologic purposes, it commonly will state the findings are benign (not cancer), malignant (cancer), or unable to be determined.
The following paragraphs generally include the specific technical information involved in obtaining and processing of the sample. The details of the diagnosis can also be found here. Because reports are generated for other medical professionals, the terminology is often medically oriented and can be difficult to interpret.
You may want to ask for a copy of the report for your records, but you should ask your healthcare provider to review the results with you.