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Sentinel Lymph Node Biopsy

Procedure overview

A sentinel lymph node biopsy is a surgical procedure that helps healthcare providers determine if or how far a cancer has spread within the body.

Lymph nodes are part of the body’s lymphatic system. The lymphatic system is one weapon your body uses to fight infections like bacteria, viruses, and other foreign materials. The lymph system consists of a clear fluid called lymph that traps these particles. This fluid flows to your lymph nodes. Lymph nodes are normally small, round organs in your neck, underarms, groin, abdomen, and chest. When infected or when cancer spreads to a lymph node, the node may become large, hard, and painful. But cancer can spread to a lymph node and it may feel exactly the same as it did before the cancer was there.

When you have a cancerous tumor, the sentinel lymph node is the node that the cancer may pass to first, before spreading to other lymph nodes. Examining cells in this node can give your healthcare provider a lot of information about the state of your cancer. To do this, your healthcare provider may order a procedure called a sentinel lymph node biopsy. The biopsy involves surgery to remove the node so that it can be examined.

Reasons for the procedure

The main reason for a sentinel lymph node biopsy is to find out the extent of your cancer—if it has spread beyond the main tumor—and help determine the best treatment for you.

It is an alternative to the traditional approach called standard lymph node removal. In that procedure, more lymph nodes are routinely removed from the region around the cancer. With a sentinel lymph node biopsy, additional lymph nodes may be removed only if signs show that the cancer has spread to the sentinel node. If the sentinel node is clear of cancer, further node excision is not necessary.

When to do a sentinel lymph node biopsy depends on the type of cancer and its location in the body. Sentinel lymph node biopsies are most often used in cases of breast cancer and melanoma.

Risks of the procedure

Sentinel lymph node biopsy is called a minimally invasive procedure, so the risks are generally less than they would be if more nodes were removed.

The most common risks of the procedure include:

  • Localized pain and swelling at the site of the biopsy

  • Bruising at the site of the biopsy

  • Decreased lymphatic drainage in the area

  • Formation of a seroma, or collection of lymph fluid

  • Allergic reactions to the contrast dye that is injected to help find the sentinel lymph node

  • Temporary reactions to the dye, such as discolored urine or stains on the skin

There may be other risks, depending on your specific medical condition. Be sure to discuss any concerns with your caregivers before rehabilitation therapy.

Before the procedure

  • Tell your healthcare provider if you are pregnant, are taking any medicines, or have any allergies, particularly to anesthesia or dyes.

  • Mention any bleeding problems and any blood-thinning medicines you’re taking, such as aspirin or warfarin.

  • Let your healthcare provider know if you’ve had a biopsy in the past or have had radiation treatment to the biopsy site.

  • Your healthcare provider may prescribe a sedative or anesthesia before the procedure. Follow all directions about when you should stop eating and drinking before the procedure. You’ll also probably need to make arrangements to have someone take you home afterward.

During the procedure

A sentinel lymph node biopsy is often done on an outpatient basis, meaning you can leave the hospital after the procedure. In some instances, you may need to stay overnight. This is how a sentinel lymph node biopsy is usually done:

  1. You may receive a sedative medicine to help you relax.

  2. You may receive local or general anesthesia. 

  3. The surgeon will inject a special radioactive substance or a blue dye, or both near the site of the tumor.

  4. The surgeon then uses a scanner to identify the lymph node that contains the radioactive substance or the blue dye. This is the sentinel lymph node. Sometimes there can be more than one.

  5. The surgeon will make a half-inch incision in the skin and remove the node with standard surgical instruments.

  6. The biopsy site will be stitched up and then covered with a bandage while it heals.

From start to finish, the procedure usually takes about 30 to 60 minutes.

After the procedure

The removal of the lymph node is just the beginning of the process with a sentinel lymph node biopsy. Once the node is removed, a healthcare provider called a pathologist dissects it into small pieces under a microscope to look for cancer.

Depending on what the pathologist finds, your medical team will outline the rest of your treatment program. In many cases, additional lymph nodes will need to be removed during a follow-up appointment. Sometimes, the pathologist can work quickly enough that the lymph nodes can be removed during the same procedure.

After the biopsy, you may feel some pain at the site of the surgery and you may be drowsy if you had anesthesia. Your healthcare provider will likely give you pain medicine. Pain should stop after a few days. A little bleeding is also not unusual at the site of the biopsy.

If you experience any of the following symptoms, contact your healthcare provider immediately:

  • Swelling at the biopsy site

  • An increase in pain or redness at the site

  • Increased bleeding from the site

  • Pus at the site

  • Fever

  • Any other concerns

Online Medical Reviewer: Hanrahan, John, MD
Online Medical Reviewer: Levy, Adam S, MD
Date Last Reviewed: 12/1/2017
© 2000-2019 The StayWell Company, LLC. 800 Township Line Road, Yardley, PA 19067. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.
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