Sentinel lymph node biopsy

This page was reviewed under our medical and editorial policy by

Daniel Liu, MD, Plastic and Reconstructive Surgeon

This page was reviewed on February 8, 2022.

A sentinel lymph node biopsy, also called a sentinel lymph node dissection, is a staging procedure that may help determine whether cancer has spread into the body’s lymphatic system from a primary tumor. It’s commonly used in both skin cancer and breast cancer patients.

The lymph nodes are an important part of your body that work to fight off infection and keep you healthy. You have hundreds of lymph nodes, which function as filters to remove harmful substances. However, sometimes cancer spreads from the primary cancer site into the lymph nodes, using the lymph system to travel.

Why is a sentinel lymph node biopsy performed?

This procedure is most commonly recommended for patients diagnosed with melanoma, breast cancer and, occasionally, penile and endometrial cancers. Doctors may recommend a sentinel lymph node biopsy to learn more about the potential progression of the disease.

The sentinel lymph node is defined as the first lymph node that cancer cells are likely to spread to from a primary tumor. By identifying the sentinel lymph node, it may then be removed and examined.

If no cancer cells are present, it’s likely that the cancer hasn’t spread into the lymph system. An advantage of this procedure is that, if the sentinel lymph node is negative, patients may be able to avoid a more extensive lymph node surgery.

For some patients, it may be a valuable tool that helps your care team map out the possible treatment plan.

What to expect

For lymph nodes deep within the body, a general anesthetic may be used, so you’ll be asleep during the procedure. This means you may need to refrain from eating or drinking for a set period of time beforehand. If the lymph node is just under the skin, a local anesthetic may be used instead. Because anesthetic is used in both scenarios, pain isn’t typically felt during the procedure.

To begin the procedure, your doctor may first need to identify the location of the sentinel lymph node, keeping in mind there may be more than one. The doctor typically injects a blue dye or a safe radioactive substance, then uses a special device to identify the location.

The surgeon may make a small incision in the skin to remove the lymph node, which may be sent to a pathologist for further examination. Removal of the primary tumor may be performed at the same time.

Typically, stitches are used to close the wound. Afterward, you may be able to go home on the same day. If general anesthetic is used, you may feel groggy, so it’s best to arrange for transportation home.

Potential risks from sentinel lymph node biopsy

Any medical procedure has the potential for complications. Below are common risks associated with sentinel lymph node biopsy.

  • Lymphedema: Removing a lymph node may cause lymphedema, which is a type of tissue swelling. The risk is low when only one lymph node is removed, but it’s more common with multiple lymph nodes.
  • Seroma: This is a lump caused by fluid buildup. While it usually goes away on its own, it may need to be drained.
  • Discomfort: After the anesthetic wears off, you may feel pain, bruising or swelling at the site of the incision.
  • Infection: The incision site needs to be kept clean to reduce this risk.
  • False-negative biopsy result: Although uncommon, this is the possibility that cancer cells aren’t detected in the sentinel lymph node, even though they’ve spread to other lymph nodes in the body.
  • Allergic reaction: Some patients experience an allergic reaction to the dye used during the procedure. Tell your doctor about any past allergic reactions.


After the results return from the pathologist, your doctor may schedule a follow-up appointment. This may also be a good opportunity for your care team to check on the incision wound and ensure it’s healing properly.

If no cancer cells were found by pathology, then it’s likely that no further treatment may be needed. Your doctor may ask that you visit for check-ups more regularly, as a way of observing your health.

If cancer cells were found, further treatment may include a procedure known as a lymph node dissection, which removes all of the lymph nodes near the primary tumor.

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