Sentinel lymph node biopsy

Published by Bupa's Health Information Team, February 2011.

This factsheet is for people who are having a sentinel lymph node biopsy (SLNB), or who would like information about it.

A SLNB procedure helps identify the first lymph node that tumour cells drain into and the sentinel lymph node is removed and tested for cancer.

You will meet the surgeon carrying out your procedure to discuss your care. It may differ from what is described here as it will be designed to meet your individual needs.

About sentinel lymph node biopsy

Lymph nodes (or glands) are part of the body's natural defence system called the lymphatic system. They are located throughout your body, particularly in the armpits, neck and groin. Their main function is to help fight infection and filter lymphatic fluid.

If you have cancer, to help plan appropriate treatment, your doctor will need to know if the cancer has spread to your lymph nodes. SLNB involves using a radioactive isotope and/or a blue dye to find the first lymph node (the sentinel node) that the cancer may drain into. The sentinel node is removed and examined in the laboratory for cancer cells (sometimes more than one node is removed).

If cancer cells are found in the sentinel node, further surgery to remove all the lymph nodes (lymphadenectomy) may be needed and/or other treatment such as radiotherapy or chemotherapy.

If no cancer cells are found, it means the cancer probably hasn't spread to the lymph nodes.

                                                        The lymphatic system

What are the alternatives?

To stage the cancer (find out if it's spread) and plan appropriate treatment it's essential that lymph nodes closest to your tumour are checked for cancer cells.

Depending on the size and location of your cancer, your surgeon may suggest having some or all the local lymph nodes removed at the same time as removing the primary tumour. For example, in some types of breast cancer the surgeon removes the lymph nodes in your armpit at the same time as the breast tumour.

Preparing for sentinel lymph node biopsy

Your surgeon will explain how to prepare for your procedure. For example, if you smoke, you will be asked to stop as smoking increases your risk of getting a chest and wound infection, which can slow your recovery.

SLNB is usually done as a day-case procedure. This means you have the procedure and go home the same day. Sometimes, if you're having a tumour removed at the same time, you may need to stay in hospital overnight.

SLNB may be done under general or local anaesthesia. General anaesthesia means you will be asleep during the procedure. Local anaesthesia completely blocks the pain from the biopsy area and you will stay awake. You may be offered a sedative with a local anaesthetic. This relieves anxiety and helps you to relax. Your surgeon and anaesthetist will discuss which type of anaesthesia is most suitable for you.

If you're having a general anaesthetic, you will be asked to follow fasting instructions. This means not eating or drinking, typically for about six hours beforehand. However, it's important to follow your anaesthetist's advice.

Your surgeon will discuss with you what will happen before, during and after your procedure, and any pain you might have. This is your opportunity to understand what will happen, and you can help yourself by preparing questions to ask about the risks, benefits and any alternatives to the procedure. This will help you to be informed, so you can give your consent for the procedure to go ahead, which you may be asked to do by signing a consent form.

What happens during sentinel lymph node biopsy

Blue dye is used either alone, or in combination with the radioactive isotope. If a radioactive isotope is used, the procedure is done in three stages.

Stage 1 – lymphatic mapping

If a radioactive isotope is used, you will be taken to the nuclear medicine department in the hospital. You don't need anaesthetic for lymphatic mapping.

You will be asked to lie on a table in the imaging room. Your radiologist (a doctor who specialises in using imaging methods to diagnose medical conditions) will inject a small amount of a radioactive isotope around your tumour. The isotope drains into nearby lymph nodes. The lymph node area is located using a scanner or a special gamma sensor and marked on your skin. Your radiologist may take X-ray pictures to show the location of the sentinel node(s).

You will return to your room or the day-care ward and wait for one hour.

Stage 2 – intradermal blue dye injection

This is usually done in the operating theatre after the local or general anaesthetic has taken effect. The blue dye is injected into the skin close to the tumour. The dye drains into the lymph nodes. Your surgeon will allow three to 10 minutes for the dye to reach the sentinel lymph node(s) and then begin the biopsy. This may be done at the same time as surgery to remove the cancer.

Stage 3 – sentinel node biopsy

The biopsy procedure usually takes 30 minutes. A cut is made into the skin and soft tissues to reach the lymph node area.

Your surgeon will follow the blue dye pathway to locate the sentinel lymph node(s). If a radioactive isotope is used your surgeon will also use the X-ray picture and a hand-held gamma sensor to identify the sentinel node(s).

The affected sentinel node(s) are removed and sent to a laboratory for testing. The skin cut is closed with dissolvable stitches.

What to expect afterwards

If you have general anaesthesia, you will need to rest until the effects of the anaesthetic have passed. You may need pain relief to help with any discomfort as the anaesthetic wears off.

After a local anaesthetic it may take several hours before the feeling comes back into the biopsy area. Take special care not to bump or knock the area.

You will have a dressing covering your biopsy area. This is usually removed on the second day.

The length of time your dissolvable stitches will take to disappear depends on what type you have. However, for this procedure they should usually disappear in about seven to 10 days.

You will need to arrange for someone to drive you home. Try to have a friend or relative stay with you for the first 24 hours after you get home.

Your nurse will give you some advice about caring for your healing wounds before you go home. You will be given a date for a follow-up appointment.

Results

Your biopsy results will be ready several days later and will usually be sent in a report to the doctor who requested your procedure. Your doctor will review the results and discuss them with you at your follow-up appointment.

Recovering from sentinel lymph node biopsy

If you need pain relief, you can take over-the-counter painkillers such as paracetamol or ibuprofen. Always read the patient information that comes with your medicine and if you have any questions, ask your pharmacist for advice.

General anaesthesia and sedation temporarily affects your co-ordination and reasoning skills, so you must not drive, drink alcohol, operate machinery or sign legal documents for 24 hours afterwards. If you're in any doubt about driving, contact your motor insurer so that you're aware of their recommendations, and always follow your surgeon's advice.

The blue dye usually flushes out in the urine making it green in colour. This is normal and nothing to worry about.

What are the risks?

As with every procedure, there are some risks associated with having SLNB. We have not included the chance of these happening as they are specific to you and differ for every person. Ask your surgeon to explain how these risks apply to you.

Side-effects

Side-effects are the unwanted but mostly temporary effects you may get after having the procedure.

Side-effects of SLNB include:

• pain, swelling and bruising in the biopsy area
• a blue stain in the skin at the injection site – this may stay blue for up to six months
• blue or green coloured urine – the discolouration only lasts a day

Complications

Complications are when problems occur during or after the operation. Most people are not affected.

Specific complications of SLNB are uncommon but can include:

• allergic reaction to the blue dye – medicines are available to treat an allergic reaction
• infection at the site of surgery – you may need antibiotics
• build up of fluid in the lymph node area (seroma)
• build up of fluid in the affected arm or leg (lymphoedema)

For answers to frequently asked questions on this topic, see Common questions.

For sources and links to further information, see Resources.