A sentinel lymph node biopsy is a surgical procedure that helps doctors 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 cancer, bacteria, and other foreign materials. The system consists of a clear fluid called lymph that traps these particles. This fluid flows to your lymph nodes. Nodes are small, round organs in your neck, underarms, groin, abdomen, and chest.
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 doctor a lot of information about the state of your cancer. To do this, your doctor may order a procedure called a sentinel lymph node biopsy. The biopsy involves surgery to remove the node so that it can be examined.
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.
There is an open question about sentinel node biopsy. It is not certain just how effective it is, compared with the traditional lymph node removal. Research studies are underway to evaluate the two approaches.
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
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.
Tell your doctor if you are pregnant, are taking any medications, or have any allergies, particularly to anesthesia or dyes.
Mention any bleeding problems and any blood-thinning medications you’re taking, such as aspirin or warfarin.
Let your doctor know if you’ve had a biopsy in the past or have had radiation treatment to the biopsy site.
Your doctor 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.
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:
You may receive a sedative medication to help you relax.
The surgeon will inject a special radioactive substance or a blue dye, or both near the site of the tumor.
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.
The surgeon will make a half-inch incision in the skin and remove the node with standard surgical instruments.
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.
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 doctor 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 doctor will likely give you pain medication. 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 doctor immediately:
Swelling at the biopsy site
An increase in pain or redness at the site
Increased bleeding from the site
Pus at the site