A biopsy is a procedure that removes a small sample of cells or tissue from your body so it can be examined under a microscope. It’s the most reliable way to determine whether a suspicious lump, spot, or area of tissue is cancerous, and it’s also used to diagnose infections, autoimmune conditions, and organ diseases. Imaging tests like CT scans and MRIs can detect masses or irregular tissue, but they can’t distinguish cancerous cells from noncancerous ones. For most cancers, a biopsy is the only way to make a definitive diagnosis.
Why Biopsies Are Performed
The most common reason for a biopsy is to investigate a suspicious area found during a physical exam or imaging scan. Your doctor may recommend one if you have a lump in your breast, an unusual mole, a polyp found during a colonoscopy, or abnormal blood work suggesting organ damage. The goal is always the same: get a definitive answer about what’s happening in that tissue.
Once the sample is removed, a specialist called a pathologist examines it in a lab. They look at the cells under a microscope and may run additional tests to check for specific markers. The results tell your doctor whether the tissue is normal, inflamed, precancerous, or cancerous, and if cancer is present, what type it is and how aggressive it appears.
Common Types of Biopsies
Needle Biopsies
Needle biopsies are the least invasive option and the most frequently performed. They come in two main forms. A fine-needle aspiration uses a very thin needle (roughly the width of a blood-draw needle) to suction out a small cluster of cells. It’s quick, causes minimal discomfort, and is often used for lumps in the thyroid, breast, or lymph nodes. Because it collects only loose cells, though, it sometimes doesn’t provide enough information for a complete diagnosis.
A core-needle biopsy uses a slightly larger, hollow needle to extract a small cylinder of solid tissue. This gives the pathologist more to work with, including the tissue’s structure and how cells are arranged relative to each other. Core biopsies are common for breast, liver, kidney, and prostate concerns. Both types are typically guided by ultrasound or CT imaging so the needle reaches exactly the right spot.
Skin Biopsies
If a mole, rash, or skin lesion looks concerning, your doctor can biopsy it right in the office. A shave biopsy skims a thin layer off the surface. A punch biopsy uses a small circular tool to remove a deeper, round sample, often requiring a stitch or two. An excisional biopsy removes the entire area of concern along with a margin of surrounding tissue, and this approach doubles as both diagnosis and treatment when the lesion turns out to be something that needed removal anyway.
Surgical and Endoscopic Biopsies
Some tissue isn’t easily reached with a needle. Endoscopic biopsies use a thin, flexible tube with a camera and tiny cutting tools, threaded through natural openings like your mouth or colon. This is how polyps are sampled during a colonoscopy or how stomach tissue is collected during an upper endoscopy.
Surgical biopsies require an incision and are reserved for situations where other methods can’t access the tissue or where a larger sample is needed. These are less common today thanks to improvements in needle and imaging technology, but they’re still used for certain deep-seated tumors or when the full architecture of a tissue sample matters for diagnosis.
Sentinel Lymph Node Biopsy
This specialized biopsy is used after a cancer diagnosis to determine whether cancer has started to spread. The sentinel node is the first lymph node that fluid drains to from the tumor site. A surgeon identifies it using a dye or radioactive tracer, removes it, and sends it to the lab. If the node is cancer-free, the disease likely hasn’t spread to other nodes or organs. If cancer cells are found, that changes the staging and treatment plan. This approach is most commonly used for breast cancer and melanoma, and it often spares patients from having a larger number of lymph nodes removed unnecessarily.
What to Expect During the Procedure
Preparation for most biopsies is minimal. Your doctor will ask about bleeding disorders, blood-thinning medications, and supplements that could increase bleeding risk. You may need to stop certain medications for a few days beforehand. For needle and skin biopsies, you’ll typically stay awake. The area is cleaned, marked, and injected with a local anesthetic. The numbing injection can cause a brief burning sensation, but after that you shouldn’t feel pain during the procedure itself.
Needle biopsies often take just a few minutes. Skin biopsies are similarly quick. Surgical biopsies may require sedation or general anesthesia and a longer appointment. Endoscopic biopsies usually involve sedation so you’re comfortable while the scope is in place.
Afterward, the site is bandaged. If stitches were placed, you’ll get instructions on wound care. The standard advice is to keep the area clean by washing gently with soap and water twice a day (once daily for scalp biopsies), patting it dry, and applying a fresh bandage. Wounds on the legs and feet heal more slowly than those on other parts of the body, so expect a longer recovery window for those locations.
Risks and Complications
Biopsies are generally safe procedures. The most common side effects are mild pain, bruising, and slight bleeding at the site, all of which typically resolve on their own within a few days. Infection is possible but uncommon when basic wound care is followed.
For more invasive biopsies, bleeding risk increases but remains low. A large review of image-guided liver biopsies found that the vast majority of studies reported bleeding rates under 2%. When bleeding did occur, most cases were minor and didn’t require any medical intervention. Major bleeding requiring treatment ranged from 0.1% to 4.6% across studies. Your personal risk depends on the biopsy location, the technique used, and whether you have conditions that affect blood clotting.
Understanding Your Results
Results typically come back within a few days to two weeks, depending on the complexity of the analysis. The pathology report will describe what the cells looked like and whether they were normal or abnormal. A few key terms are worth knowing.
- Benign means the tissue is not cancerous. You may still need monitoring or treatment for whatever condition was found, but cancer has been ruled out.
- Malignant means cancer cells were identified. The report will usually specify the type and grade of cancer, which helps guide treatment decisions.
- Negative margins mean the pathologist found no cancer cells at the edges of the removed tissue, suggesting the abnormal area was completely removed.
- Positive margins mean cancer cells were found at the edges, which may mean additional surgery or treatment is needed to address tissue left behind.
- Dysplasia describes cells that look abnormal but aren’t cancer yet. Depending on the severity, this may require monitoring, removal, or follow-up biopsies.
Sometimes a biopsy result is inconclusive, meaning the sample didn’t provide enough information for a clear diagnosis. This doesn’t mean something is wrong. It usually means a repeat biopsy or a different sampling technique is needed.
Liquid Biopsies
A newer approach called a liquid biopsy analyzes a standard blood draw for fragments of tumor DNA, whole tumor cells, or other molecular signals shed by cancers into the bloodstream. Unlike tissue biopsies, liquid biopsies don’t require needles in organs or surgical incisions. They’re currently used in oncology to monitor how a cancer is responding to treatment, detect whether cancer has returned after treatment, and in some cases help identify therapeutic targets.
Liquid biopsies are particularly useful when repeated sampling is needed, since a blood draw is far simpler to repeat than a tissue biopsy. They’re also valuable for patients who can’t easily tolerate invasive procedures. Some can even be performed with at-home blood collection kits. While liquid biopsies don’t yet replace tissue biopsies for initial cancer diagnosis in most situations, their role in cancer care continues to expand.