Sentinel Lymph Node Biopsy
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Sentinel Lymph Node Biopsy

En Español (Spanish Version)


A sentinel lymph node biopsy is the removal and testing of a lymph node (or nodes) to determine if it contains cancer cells.

Lymph nodes are aggregates of lymphoid tissue contained within an encapsulated structure located along lymphatic vessels. Lymph nodes are part of the immune system. This system fights infections and disease. Lymph nodes filter lymphatic fluid, which is a fluid formed when blood circulates through the blood vessels and noncellular containing fluid accumulates within the soft tissues. Lymph is collected from tissues throughout the body and flows through the lymphatic system. The lymph nodes then collect foreign material (including bacteria, viruses, and cancer cells) and hold them for the body’s defense mechanisms (immune system) to attack.

Cancer often spreads from the primary tumor to the nearest lymph node or nodes. The lymph node first to receive the material from an area of the breast is called the sentinel lymph node. It is important to understand that the sentinel node will probably be the first one to get cancer in it if cancer has spread to the lymph nodes at all.

Sentinel lymph node biopsy is often done during cancer-removal surgery. Sentinel lymph node biopsy is part of the staging process. Staging is an attempt to determine if cancer has spread and, if it has, what body parts are affected.

Lymph Node Biopsy

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Parts of the Body Involved

The body parts involved depend on the type of cancer. Sentinel lymph node biopsy is often used in staging malignant melanoma and breast cancer . It is done in patients with small tumors and no sign of spread to lymph nodes. It may be used with other cancers, though it is still considered experimental in assessing the spread of any tumor other than breast cancer and melanoma.

Reasons for Procedure

Sentinel lymph node biopsy is done to determine if cancer cells have spread from the primary tumor to nearby lymph nodes.

Risk Factors for Complications During the Procedure

An allergy to the dye or radioactive tracer given for the biopsy could result in complications.

The following conditions can increase the risk of surgical complications:

  • Obesity
  • Chronic illness
  • Advanced age
  • Smoking
  • Poor nutritional status
  • Use of certain medications or dietary supplements
  • Bleeding disorders

What to Expect

Prior to Procedure

Prior to surgery, your doctor will do a physical exam and a biopsy of the cancerous tissue. Tests may include the following:

  • Blood tests
  • Urine tests
  • A mammogram , in cases of breast cancer

In the days leading up to your procedure:

  • Review your regular medications with the surgeon. You may be advised to stop taking certain drugs:
    • Aspirin
    • Anti-inflammatory drugs (eg, NSAIDs)
    • Anticoagulant (blood-thinning) drugs
  • The night before, eat a light meal and do not eat or drink anything after midnight.
  • Arrange for a ride to and from the hospital.

During Procedure

IV fluids, anesthesia


General, local, or regional, depending on the location of the lymph node

Description of the Procedure

A sentinel lymph node biopsy is usually done during cancer-removal surgery.

Several hours before the surgery, a radioactive substance is injected near the tumor.

To begin the procedure, you'll be given anesthesia. Then, the doctor injects a blue dye and often a radioactive tracer. This substance helps the doctor identify the sentinel lymph node, it will be blue and emit a small amount of radiation. A special device is used to pick up that radioactive signal. The surgeon makes a small incision and removes the sentinel node (or nodes). The sentinel lymph node (or nodes) is checked for cancer cells. If cancer cells are found, the surgeon removes the rest of the lymph nodes in that area. The lymph nodes may also be taken out if the sentinel lymph node cannot be located.

If cancer cells are not seen in the sentinel node, it is unlikely that the cancer has spread to the lymph nodes. The other lymph nodes are not removed.

After Procedure

The sentinel node is examined by a pathologist.

How Long Will It Take?

The sentinel lymph node biopsy takes about 30 to 60 minutes. This entire cancer-removal surgery takes longer.

Will It Hurt?

Anesthesia prevents pain during surgery. Pain medications are given during recovery.

Possible Complications

Possible complications of this procedure include the following:

  • Infection
  • Bleeding or bruising
  • Scarring

If the lymph nodes are removed, there is an increased risk of the following:

  • Delayed would healing
  • Additional pain
  • Lymphedema, a condition in which fluids collects in the tissues

Average Hospital Stay

Sentinel lymph node biopsy may be performed on an outpatient basis. But, depending on the type of cancer-removal surgery you have, you may need to stay in the hospital.

Postoperative Care

Keep the surgical area clean and dry.


The result of the sentinel lymph node biopsy determines if additional lymph nodes need to be removed. It can also help determine the severity of your cancer.

Call Your Doctor If Any of the Following Occurs

  • Signs of infection, including fever and chills
  • Redness, swelling, increasing pain, excessive bleeding, or discharge from the incision site
  • Cough, shortness of breath, chest pain, or severe nausea or vomiting
  • New, unexplained symptoms


American Cancer Society

National Cancer Institute


Canadian Cancer Society

Health Canada


Alazraki NP, Styblo T, Grant SF, et al. Sentinel node staging of early breast cancer using lymphoscintigraphy and the intraoperative gamma detecting probe. Radiol Clin North Am . 2001;39:947-956.

American Cancer Society website. Available at: .

Clinical Oncology . 2nd ed. Churchill Livingstone, Inc.; 2000.

Conn's Current Therapy 2002 . 54th ed. WB Saunders Co.; 2002.

Dauway EL, Giuliano R, Haddad F, et al. Lymphatic mapping in breast cancer. Hematol Oncol Clin North Am . 1999;13:349-371.

Hieken TJ. The role of sentinel node biopsy in skin cancer ( September 15, 2006). eMedicine website. Available at: .

Leong SP. The role of sentinel lymph nodes in malignant melanoma. Surg Clin North Am . 2000;80:1741-1757.

National Cancer Institute website. Available at: .

Veronesi U, Paganelli G, Viale G, et al. Sentinel-lymph-node biopsy as a staging procedure in breast cancer: update of a randomized controlled study. Lancet Oncol . 2006;7: 983-90.

Last reviewed January 2008 by Igor Puzanov, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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