Patient Guide · Sentinel-Node Biopsy
Your surgeon has plannedsentinel-node biopsy.Here's what it means.
Sentinel-lymph-node biopsy is a smaller, more focused operation than the older, wider surgery it replaces. Before surgery, a small amount of a tracer is injected near your tumour — it travels to the "sentinel" node (the first one the cancer would reach). During surgery, your surgeon uses a small handheld probe to find and remove just that one node. If it\'s clean — which is what happens for most patients — you avoid the larger surgery and the long-term problems it causes (like a swollen arm or nerve pain). This page walks you through the tracer injection, the day of surgery, the small radiation dose, and what to ask your team.
Important: this page is educational. It does not replace the specific advice of your surgical, nuclear-medicine and oncology team, who know your tumour type, staging and imaging. Always follow their instructions in preference to anything on this page.
What is a gamma-probe biopsy?
Finding one specific node instead of removing many
A small handheld device that helps your surgeon find one specific lymph node
Cancer sometimes spreads to nearby lymph nodes — small bean-shaped structures that filter body fluid — before it shows on scans. Instead of removing many lymph nodes to check, your surgeon can find and remove just the first one that cancer would reach (called the "sentinel" node — like the sentinel guarding a gate). The device, called a gamma probe, is guided by a small amount of a tracer injected before surgery. It tells the surgeon exactly where the sentinel node is. If that one node is clean, no more lymph nodes need to come out.
A smaller operation with fewer long-term problems
The main benefit is what this smaller operation lets you avoid. In about 7 or 8 out of every 10 breast cancer patients, the sentinel node is clean — so you don't need the older, larger operation. That older operation used to leave many patients with swollen arms, nerve pain and stiff shoulders for years. Finding the sentinel node with a gamma probe is now the standard of care around the world.
A very small radiation dose
The tracer used is a small dose of a mildly radioactive material — the amount of radiation is similar to (or less than) a routine chest X-ray. You are not radioactive enough for anyone around you to need to keep their distance. The tracer clears from your body within a day or two.
Where sentinel biopsy is used
Three main cancer settings in Indian centres
Breast cancer
The most common use. If your breast surgeon plans to check the lymph nodes under your arm, the gamma probe helps them find just the sentinel one — instead of removing many.
Typical workflow
Same-day procedure: tracer injected 2 to 24 hours before, and the probe is used during your operation. If the sentinel node has cancer in it, the surgeon may go on to remove more lymph nodes either the same day or in a follow-up procedure.
Melanoma (a type of skin cancer)
For medium-thickness melanomas, checking the sentinel lymph node is the accepted way to see whether the cancer has started to spread. The gamma probe guides the surgeon to the right node.
Typical workflow
Tracer injected around the melanoma the morning of surgery. The probe finds one or sometimes several sentinel nodes. If clean, no further lymph-node surgery is needed.
Cancers of the uterus, vulva or mouth
The same idea is used for some cancers of the uterus (endometrial cancer), vulva, and mouth. Instead of removing many pelvic or groin lymph nodes with all the after-effects that causes, the surgeon removes just the sentinel node. Sometimes combined with a fluorescent dye that lights up the node for extra visual confirmation.
Typical workflow
Injection near the tumour on the day of surgery. Surgery follows within hours.
How to prepare
The day before + the morning of surgery
The tracer injection (day of or day before surgery)
You visit the nuclear-medicine department for a small injection — usually 2 to 4 tiny injections just under the skin around your tumour. It can sting briefly. This happens 2 to 24 hours before your surgery (or the same morning for some breast cancer patients).
A short scan (some centres)
Some hospitals do a short scan about 30 minutes to 2 hours after the injection. The scan simply shows where the tracer went — helpful for your surgeon. Lie still for about 15 to 20 minutes; nothing else to do.
No fasting for the injection itself
The tracer injection doesn't need fasting. Your surgery does need fasting for the anaesthetic — your surgical team will tell you when to stop eating and drinking.
Pregnancy check
Because a small dose of radiation is used, women who could become pregnant will need a pregnancy test first. This is a routine safety check.
Bring your reports
Bring all your scan reports (mammogram, MRI, PET, CT), your biopsy report, any earlier surgical records, and a list of medicines you take. Bring these to both the nuclear-medicine department and to your surgical team.
Bring someone to drive you home
Most patients go home the same day (breast, melanoma) or stay a night or two. Bring someone to drive you after the anaesthetic wears off. Wear loose comfortable clothes for the trip home.
In the operating room
A short, targeted procedure
- 1
Anaesthetic
Most patients have a general anaesthetic (you're asleep). Some smaller procedures use only local anaesthetic and sedation. Your anaesthesia team will explain which one is right for you.
- 2
Scanning the skin
Before any cut is made, the surgeon runs the probe over your skin to find the "hot spot" — the spot where the tracer has settled in the sentinel node underneath. This tells them exactly where to make a small, targeted cut.
- 3
Finding + removing the sentinel node
Through the small cut, the surgeon uses the probe to guide right to the sentinel node. The real sentinel node reads much stronger than nearby tissue on the probe. Once found, it's removed carefully.
- 4
Checking nothing was missed
The surgeon rechecks the area with the probe to make sure no other important node was missed. If any extra sentinel node is found, it's also removed.
- 5
Closing up + recovery
The cut is closed and you wake up in recovery. The removed node(s) are sent to the pathology lab; results usually take 3 to 7 days. Some hospitals get a quick preliminary result during surgery — this lets the surgeon decide there and then whether to remove more.
After surgery
Recovery + waiting for the pathology result
Wound care
A small dressing over the cut. Keep it dry until your surgical team says otherwise (usually 24 to 48 hours). Some bruising or a small pocket of clear fluid at the site is normal and settles on its own. Call your team if you see redness spreading, pus, a fever, or the wound opening.
You're not radioactive any more
The tracer used is very short-lasting — most is already gone by the time surgery starts, and what's left clears within a day or two. You don't need to keep distance from family, avoid children, or restrict any activity for radiation reasons. If you happen to travel and set off an airport radiation alarm in the next 48 hours (rare), the team can give you a small card that explains it.
Getting back to normal
This is a much smaller operation than the older one it replaces. Most people return to light activity within days and normal activity within 1 to 2 weeks. Your surgical team will give you specific timings based on the main tumour operation done at the same time.
Waiting for the pathology result
The pathology result on the sentinel node is the whole point. If it's clean, you avoid the larger operation and its long-term problems. If it shows cancer, your team will talk you through what happens next — sometimes more surgery, sometimes closer monitoring, sometimes other treatments. This is a real conversation with your team, not a template answer.
Worth knowing · Probe technology
Not all gamma probes deliver the same signal quality
The probe your surgeon uses is one of the reasons why sentinel-node biopsy actually works — a low-sensitivity probe can\'t reliably tell a real sentinel node apart from a scattered "hot" background, especially deep in the axilla or groin. Two probe features are worth asking your surgical team about.
How sensitive is the probe?
The whole approach works only if the probe can clearly tell the real sentinel node apart from background signal in the surrounding tissue. Modern probes (like the Europrobe family) use a very sensitive detector material that gives a clean, precise reading — so the surgeon can be confident about which node is the sentinel, even in tricky areas like under the arm or in the groin. This is the difference between "probably here" and "yes, this exact node".
Some centres combine radiation + dye
Some hospitals combine the small radioactive tracer with a fluorescent dye that lights up the node under a special light. Two signals confirming the same node adds an extra layer of confidence. Newer probes handle both in one device. If your hospital does this, that's current best practice — worth asking your surgeon about.
The technical specification of the Europrobe 3.2 gamma detection system supplied through Saxsons Group is on theclinical evidence library — including the NSABP B-32 and MSLT-I trials that anchored sentinel-node biopsy as standard of care.
Questions to ask your care team
Eight questions worth writing down
Take this list to your pre-surgery consultation. Different centres do things slightly differently — clarify how yours works.
- ❓Are you planning to check just the sentinel node, or remove a larger group of lymph nodes? Why?
- ❓When and where will the tracer be injected — the day before, or the morning of surgery?
- ❓Will I have a short scan before surgery to map where the tracer went?
- ❓Does your OR team also use a fluorescent dye, or just the probe?
- ❓When will I get the pathology result?
- ❓If the sentinel node shows cancer, what's the plan — more surgery in the same operation, or later?
- ❓What are the wound-care instructions?
- ❓When can I go back to work / driving / normal activity?