Sentinel Lymph Node Mapping for Gynecologic Cancer

Sentinel lymph node mapping is a procedure in which doctors inject a radioactive substance, a color tracer, or fluorescent dye to find out if cancer has spread.

Your doctor follows the dye's path to the first lymph node, called the sentinel lymph node. This lymph node is the one to which cancer is likely to spread first. Doctors then perform a sentinel lymph node biopsy, removing that lymph node for testing.

A negative test means no further surgery is necessary. A positive test indicates cancer has spread beyond the tumor. Doctors may do another surgery to remove more lymph nodes and/or recommend additional treatment after surgery.

Find the Right Care For You

What Is Sentinel Lymph Node Mapping?

Sentinel lymph node mapping is a surgical procedure for people with early-stage cancer. It helps identify the first lymph nodes that cancer is likely to spread to.

The lymphatic system is the pathway that carries infection-fighting white blood cells throughout the body. Cancer cells also spread to other tissues and organs through the lymphatic system. So the lymph nodes are important in diagnosing and treating cancer.

For example, endometrial cancer cells can travel from the lining of the uterus through the lymphatic channels and travel to the lymph nodes along the blood vessels in the pelvis on both sides.

To determine whether cancer has spread from the original site or tumor, doctors remove certain lymph nodes and send them to a laboratory for testing. This test is called a sentinel lymph node biopsy.

How does sentinel lymph mapping work?

During sentinel lymph node mapping, doctors inject dye into a major lymph node near the cancer site. The dye identifies the sentinel (or draining) lymph nodes. This means they are the first ones cancer cells would spread to after leaving the uterus, cervix, or vulva.

The dye makes these lymph nodes light up, showing which ones are the drainage nodes so doctors can remove them. Lighting up during the procedure does not determine whether there is cancer within the lymph node. Pathologists look at the biopsy sample under a microscope in a lab to determine if it's cancerous.

If nothing lights up during the sentinel lymph node mapping, doctors may perform a traditional lymph node dissection. This is the removal of all lymph nodes in a specific body region. It is also called a lymphadenectomy or lymph node removal.

Sometimes, people have more than one sentinel lymph node. However, doctors rarely remove more than five.

After the sentinel lymph node or nodes are removed, they are sent for testing. A negative test means the cancer has not spread, and no more lymph nodes need to be removed.

A positive test means the cancer has spread. More lymph nodes may need to be removed to determine how far the cancer has traveled through the body. Your doctor may recommend additional treatment after surgery.

Removing lymph nodes can lead to serious complications. However, removing fewer lymph nodes usually means fewer side effects. Sentinel lymph node mapping helps reduce the number of lymph nodes that must be removed and avoid complications in patients whose cancer has not spread.

Types of sentinel lymph node mapping

Doctors can perform sentinel lymph node mapping throughout the body. They typically use one of these methods:

Radioisotope method — Doctors who use the radioisotope method inject a radioactive substance, or tracer, into the tumor. They can then follow the tracer to the sentinel lymph node using a gamma probe.
Blue dye method — Doctors who use this method inject blue dye into the tumor. They can then follow the dye’s path. The lymph node or nodes that turn blue are the sentinel lymph nodes.
Indocyanine green method — Doctors who use this method inject indocyanine green, which is a fluorescent dye, into the tumor. Doctors use a fluorescent camera to identify lymph nodes that turn fluorescent green.
Combined method — Doctors often use a tracer and blue dye or indocyanine green dye to locate the sentinel lymph nodes. Using both methods together can sometimes provide a more accurate result than using either method alone.

Conditions we treat with sentinel lymph node mapping

Sentinel lymph node mapping is most often used in people who have been diagnosed with:

Researchers are currently studying the use of sentinel lymph node mapping in other cancer types, including:

Colorectal cancer.
Esophageal cancer.
Gastric cancer.
Head and neck cancer.
Non-small cell lung cancer.
Thyroid cancer.

Why Would I Need Sentinel Lymph Node Mapping?

Your doctor may suggest sentinel lymph node mapping to determine if your cancer has spread. It’s most often used in patients with endometrial cancer, breast cancer, and melanoma.

Who is a candidate for sentinel lymph node mapping?

If you have endometrial, breast, skin, or penile cancer and you don’t yet know if the cancer has spread, your provider may suggest sentinel lymph node mapping.

Mapping allows care teams to locate the lymph node where your cancer is most likely to spread first. They can then remove and test that lymph node before determining if you need further surgery or other treatments.

Doctors would not use sentinel lymph node mapping if:

They have already determined that you have cancer in the lymph nodes.
Your cancer has metastasized, or spread, to another part of your body.

What are the alternatives to sentinel lymph node mapping?

In people whose cancer has already spread or is likely to spread, doctors can skip sentinel lymph node mapping and perform a lymphadenectomy, or lymph node dissection. That’s surgery to remove all of the lymph nodes in a specific body region.

What are the risks and complications of sentinel lymph node mapping?

Doctors use sentinel lymph node mapping and biopsy before a lymphadenectomy because the procedure often has fewer side effects. However, whenever lymph nodes are removed, complications can occur.

They include:

Allergic reaction to the radiotracer, blue, or fluorescent dyes.
Bleeding, infection, or bruising at the biopsy site.
False-negative test result.
Lymphedema, or a buildup of fluid in the limbs that causes pain and swelling.
Seroma, a mass or lump caused by a buildup of fluid at the incision site.
Tingling, numbness, or pain.

What Should I Expect from Sentinel Lymph Node Mapping?

How to prepare for sentinel lymph node mapping

Doctors can perform sentinel lymph node mapping during the surgery to remove your tumor, or the procedure can be performed on its own. Either way, sentinel lymph node mapping typically takes place in a hospital under general anesthesia.

To prepare for the procedure, you should:

Fast for a certain period before the procedure. Your doctor will tell you if you need to fast and, if so, how long (usually overnight).
Let your doctor know about all medications (prescription and over-the-counter). Include any herbal remedies or other supplements you are taking.
Schedule any tests that your doctor recommends. For example, your doctor may request a blood test before the procedure to determine how long it takes your blood to clot.
Tell your doctor if you are breastfeeding, pregnant, or think you might be pregnant.
Tell your doctor if you are sensitive or allergic to any medications, iodine, latex, tape, or anesthetic agents (local and general).
Tell your doctor if you have a history of bleeding disorders or if you are taking any blood-thinning medications or aspirin. You may need to stop some of the medications before the procedure.
Tell your doctor if you have any other health conditions. Your care team may need to take certain precautions during your procedure for your safety.

How long does sentinel lymph node mapping take?

If your doctor is doing only sentinel lymph node mapping and biopsy, it will take 30 to 60 minutes.

If your sentinel lymph node mapping and cancer surgery occur together, the procedure may take several hours. You will also need to spend time in the recovery room.

During your sentinel lymph node mapping

Your surgical team will:

Locate the sentinel lymph node — Doctors inject the dye or radioactive tracer and follow its path. The first lymph node the dye or tracer reaches is the sentinel lymph node.
Give you general anesthesia — You will be asleep during the operation and won’t feel any pain.
Remove the sentinel lymph node — The surgeon will make a small incision and remove the sentinel lymph node for biopsy. Your surgeon may also remove your tumor during the same operation.
Send your sentinel lymph node biopsy sample to a lab — A pathologist will examine it and determine if cancer is present.

How painful is sentinel lymph node mapping and biopsy?

Your doctor will numb the area with a local anesthetic to inject the dye or radioactive tracer. You may feel a quick pinprick.

You’ll be asleep during the surgery to remove your lymph node. You shouldn’t feel any pain during your procedure.

After your procedure, you may have some discomfort or bruising.

Recovery after sentinel lymph node mapping

After the procedure is complete, your care team will monitor you in the recovery area before you’re discharged or transferred to a hospital room.

If you had a biopsy alone, your doctor may discharge you that day. You will need someone to drive you home.

If you had an additional surgical procedure to remove your tumor, you may need to spend one or more nights in the hospital.

Before you go home, your doctor will tell you:

How to care for your incision and watch for signs of infection or complications.
What medications you need to take.
When to call your doctor or 911 for certain symptoms.
When to schedule your follow-up appointments if one has not already been scheduled.
When you can return to your normal activities, such as driving and bathing.

Recovery after sentinel lymph node mapping and biopsy depends on the type of surgery your doctor performs. Sometimes, the procedure will be part of a traditional surgery with a larger incision. These incisions can take time to heal.

At UPMC, we usually use minimally invasive surgery to do sentinel lymph node mapping. Minimally invasive surgery requires several smaller incisions — or no incisions at all. It often results in less pain and a faster recovery.

After either type of surgery, you can expect:

Blue urine or stool if your doctor used the blue dye method.
Soreness near the incision.
Tingling or numbness.

What do the results of a sentinel node biopsy mean?

You may get your results within a few days, but it may take up to a couple of weeks.

If your pathology results show that no cancer has been found, you will not need additional surgery to remove your lymph nodes.
If the results show cancer, you may need a procedure to remove more lymph nodes. In some cases, no additional surgery is necessary if cancer is detected.
Your doctor will contact you to discuss your results and outline the next steps in your treatment plan.

When to call your doctor about sentinel lymph node mapping complications

You should call your doctor if you experience the following symptoms:

Difficulty breathing.
Dizziness.
Fever of over 100 F.
Redness, bleeding, drainage, or swelling near the incision.
Rash.
Swelling of the face.
Worsening pain that pain relievers can't control.

These can be signs of an infection or allergic reaction.

What’s the success rate of sentinel lymph node mapping?

According to a study in Gynecologic Oncology, sentinel lymph node mapping is as accurate as, or more accurate than, a lymphadenectomy for diagnosing cancer in the lymph nodes. The specific success rates vary slightly by cancer type.

The same study also found that sentinel lymph node mapping was associated with fewer long-term complications than lymphadenectomy.

Why Choose UPMC for Sentinel Lymph Node Mapping?

At UPMC, we provide expert care for gynecologic cancer. You can expect:

Compassionate care — At UPMC, you're not alone in your fight against gynecologic cancer. Our team will not only provide you with the latest advancements in cancer care but also guide and support you through diagnosis, treatment, and survivorship.
Expert surgeons — Surgeons at UPMC use minimally invasive surgery for almost all gynecological conditions. This results in faster recovery times and fewer complications for patients. UPMC is also a national leader in robotic surgery.
Locations close to home — UPMC offers breast and gynecologic cancer services in communities across the region. You don’t have to travel far from home to receive the world-class care you need.
Multidisciplinary care — We collaborate across different specialties to diagnose and treat gynecologic cancer.
National recognition— UPMC Hillman Cancer Center is one of just 57 National Cancer Institute-designated Comprehensive Cancer Centers in the country — and the only one in western Pennsylvania. The designation isn’t just an accolade. It’s an assurance that your cancer treatment is grounded in the latest advances in clinical care and supported by evidence-based research.

By UPMC Editorial Staff. Last reviewed on 2026-08-11.

References