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Sentinel lymph node biopsy
Category: Biopsies, Lab & Pathology Tests · All biopsies, lab & pathology tests
What it is
Sentinel lymph node biopsy identifies and removes the first lymph node(s) that drain a tumour site — the 'sentinel' nodes — using a radioactive tracer and/or blue dye injected near the tumour. If these nodes are clear of cancer, the remaining nodes are very likely clear too, sparing full node clearance and its complications.
Why it is done
It stages breast cancer (armpit nodes) and melanoma (the draining node basin), and is used in some other cancers, when scans show no obvious nodal spread and the nodes feel normal.
How to prepare
You will have a tracer injection near the tumour — for breast cancer sometimes the day before or the morning of surgery — with a scan to map the node location. The operation is usually combined with the tumour surgery under general anaesthetic; fasting applies. Tell the team about allergies (including to blue dye) and pregnancy.
What happens during the procedure
During surgery, the surgeon uses a gamma probe (detecting the tracer) and looks for blue-stained nodes to find and remove the sentinel node(s) — usually one to three. They are examined in the laboratory, sometimes with a rapid assessment during the operation in breast surgery. It adds about 20 to 30 minutes.
Afterwards — recovery & results
Recovery follows your main operation. Blue dye can discolour urine and skin temporarily (and rarely causes allergy). If the sentinel node contains cancer, the team discusses further node treatment — which today may be radiotherapy or targeted approaches rather than automatic full clearance, depending on the cancer and findings.
Risks & considerations
Risks include the general operation risks plus a small chance of a false-negative result (cancer present in other nodes despite a clear sentinel node — low, a few percent), lymphoedema risk that is much lower than with full clearance but not zero, and dye reactions (rare).
Watch: Sentinel lymph node biopsy videos
Real procedure videos from the MedicalVideos.com library. Some clinical footage is graphic — that is the nature of a medical video library.
Related guides on MedicalVideos.com
Frequently asked questions
Why not clear all the nodes to be safe?
Full clearance causes lymphoedema (arm swelling) in a substantial minority and does not improve survival when the sentinel node is clear. Sentinel biopsy gives the staging information with far less harm.
What does 'micrometastasis' mean if found?
A very small deposit of cancer cells in the node. Its significance and whether it changes treatment depend on the cancer type and overall plan — your team will explain your specific result.
Related procedures — Biopsies, Lab & Pathology Tests
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