Biopsy vs. Aspiration: What's the Difference?

These two words often turn up side by side, which is confusing, because they are not opposites. A biopsy is the removal of a sample of tissue or cells so a pathologist can examine it. A pathologist is a doctor who looks at cells under a microscope. Aspiration describes how a sample is taken. It means drawing out fluid or cells through a thin needle, using suction. So fine-needle aspiration is one kind of biopsy.

Aspiration means using suction through a thin needle to pull out fluid or loose cells. It has two common uses:

• To collect cells for examination. This is called fine-needle aspiration, and it is a type of biopsy.
• To drain fluid. Sometimes fluid collects in a cyst, a lump, or a space in the body. Aspiration removes it. That can relieve pressure, and it lets a lab study the fluid.

A biopsy is the broader idea. It means removing a sample so it can be examined under a microscope. NCI describes several ways of doing this. A doctor may use a needle to withdraw tissue or fluid. A doctor may use an endoscope, a thin lighted tube passed into the body. Or a surgeon may remove tissue during an operation. Some biopsies need a sedative or anesthesia.

• Fine-needle aspiration uses a very thin needle to draw out individual cells or fluid.
• Core needle biopsy uses a slightly larger needle. It removes a small cylinder of tissue, so the cells stay in their natural arrangement.
• Surgical (open) biopsy removes a larger sample during a procedure. Sometimes it removes the whole area.

A larger sample shows more than what the cells look like. It also shows how they are arranged together, and that can add useful information.

The method depends on where the area is, what your team suspects, and how much tissue is needed. Sometimes a quick aspiration is enough. Other times a core or surgical biopsy is needed. Occasionally an aspiration comes first and a larger biopsy follows. Your care team picks the approach that fits your situation, and explains what to expect.

A biopsy is common and usually very safe. The NHS notes that you may have some soreness afterwards, and that the main risk is an infection at the site. With some types of biopsy there is also a small risk of bleeding inside the body. If that applies to you, your team will tell you what to watch for.

NCI says the pathologist usually sends the report to your doctor within 10 days after the biopsy. If you have not heard anything by then, call and ask.

• Call 911 or go to an emergency department if you have heavy bleeding from the biopsy site that does not stop with steady pressure, or you feel faint, short of breath, or have severe or worsening pain in your chest or belly.
• Call your care team the same day if you have a temperature of 100.4°F (38°C) or higher, or blood or fluid is oozing from the biopsy site. Anyone on chemotherapy should treat that temperature as an emergency instead and seek care straight away, because a fever during treatment can be the only sign of a fast-moving infection (CDC).
• Call your care team the same day if the pain is getting worse, or painkillers are not helping.
• Call your care team within a day or two if the site is swollen, or red and warm. Redness can be harder to see on brown or black skin, so also go by swelling, warmth and tenderness.

• National Cancer Institute — Tests and Procedures Used to Diagnose Cancer
• National Cancer Institute — Surgical Pathology Reports
• NHS — Biopsy
• CDC — Fever and Cancer Treatment