Sentinel lymph node biopsy

What is a sentinel lymph node biopsy?

Lymph nodes are small glands that filter lymph fluid. A sentinel node is one of the first nodes draining the area where a melanoma developed. A sentinel lymph node biopsy, or SLNB, removes selected nodes so they can be checked for melanoma cells.

This is a staging test: it helps assess whether melanoma has reached the sampled nodes and informs the next steps in care. It is not needed for every melanoma. Your surgeon considers the depth and other features of your melanoma and discusses the benefits and risks with you.

Microscopic deposits may be too small to show on ordinary imaging. A negative biopsy means no melanoma cells were found in the sampled nodes; ongoing follow-up is still needed.

Mapping and preparation

Bring a current list of medicines, vitamins and supplements, and tell us about allergies to medicines, latex, antiseptics or dressings. Let the team know about diabetes, circulation problems, previous healing difficulties or a tendency to develop thick scars.

Do not stop blood thinners or change prescribed medicines without advice from your treating team. This includes prescribed aspirin. Ask about any medicine instructions before your appointment.

For a procedure under local anaesthetic alone, fasting is usually not needed unless you have been told otherwise. If sedation or general anaesthetic is planned, follow the fasting and medicine instructions provided by your hospital or anaesthetic team. Call if these are unclear.

• Bring your Medicare card, relevant referral or test results, and comfortable clothing that gives access to the treatment area.
• Discuss transport home. Arrange a responsible adult after sedation or general anaesthetic. Wound location, pain and movement can affect driving even after local anaesthetic.
• Smoking can slow healing. Ask your GP or the clinic for help stopping before surgery and during recovery.
• Ask about the benefits, risks, alternatives and likely scar before giving consent. You can ask for more time or further explanation.

Before surgery, the nuclear medicine team may inject a small amount of tracer around the original melanoma site and take images to map which nodes drain that area. This is called lymphoscintigraphy. Confirm the location and timing of this appointment with your team.

Tell the nuclear medicine team if you are pregnant, may be pregnant or are breastfeeding so they can give appropriate advice. Let the surgical team know about any allergies.

What happens during surgery

SLNB is commonly performed under general anaesthetic at the same operation as a wide local excision. A probe detects the tracer, and blue dye may also help locate the node or nodes. The surgeon makes an incision, removes the selected nodes and closes the wounds.

You may have wounds at the melanoma site and at one or more lymph node sites. The discharge plan depends on the operation and your recovery; arrange someone to take you home.

Looking after your wounds

Follow the separate instructions for each wound. Keep dressings dry for the time advised, then wash gently when allowed. Do not soak the wounds or swim until cleared. If the melanoma site was closed with a graft or flap, follow that specific care plan.

If blue dye was used, it may temporarily change the colour of your urine or stain the skin. Ask the team what to expect. Contact the clinic about any change you are unsure about.

Take pain relief as directed. Gentle movement may be encouraged, but avoid heavy lifting, strenuous exercise and movements that pull on the wounds until your surgeon advises. Confirm when you can drive after anaesthesia and once you can move safely.

Possible problems

• Seroma: a collection of fluid at the node site. Report new swelling; do not try to drain it yourself.
• Bleeding or a collection of blood under the wound.
• Infection, wound opening or delayed healing.
• Temporary or persistent altered sensation near the incision.
• Lymphoedema: persistent swelling due to changes in lymph drainage.
• An allergic reaction to dye used during the procedure.

Tell the team about increasing swelling, tightness or discomfort in the limb or around the node site.

Your results and follow-up

Lymph node samples need detailed examination and can take longer than a routine skin biopsy. Results often take around two to four weeks, but timing varies. Confirm when your surgeon expects to see you for results.

A clinician will call you if your results require urgent action. Otherwise, your results will be discussed with you at your follow-up appointment.

Confirm your review appointment before leaving. If it has not been arranged, or your results are taking longer than expected, call the clinic. No contact does not mean a result is clear.

Understanding pathology results and follow-up →

If no melanoma cells are found

A negative result is reassuring, but it does not remove the need for ongoing skin and lymph node checks. Your surgeon will recommend a follow-up plan.

If melanoma cells are found

A positive result helps determine the melanoma stage. It does not by itself show that melanoma is present throughout the body. Your specialist team will discuss whether further imaging, closer monitoring, drug treatment or other care is appropriate.

When to seek help

• Increasing or spreading redness, warmth or swelling.
• Pain that is getting worse rather than settling, pus, a new unpleasant smell, fever or feeling unwell.
• A wound that opens, a rapidly growing swelling, or a dressing that is repeatedly soaked.
• An unexpected change in the colour or appearance of a graft, flap or BTM wound.

Call 07 7520 8580 promptly. If the clinic is closed and the problem is urgent, seek an urgent medical assessment. Do not wait for a routine review.

For bleeding, apply firm, continuous pressure with a clean dressing. If bleeding persists despite pressure, seek urgent care. For severe bleeding, collapse or another medical emergency, call 000.