Breast sentinel lymph node injections

Before you have surgery to remove 1 or more lymph nodes, you'll have this test for cancer cells. A sentinel lymph node injection helps the surgeon to identify which lymph nodes should be removed.

The injection is given in the nuclear medicine department, and is usually done on the day of your surgery, or the day before.

Preparing for a breast sentinel lymph node injection

There is no special preparation for this injection. However, your surgery team might ask you to follow some instructions about eating and drinking. Please check with them when you can eat or drink. You should be prepared to be in the nuclear medicine department for up to 15 minutes.

If you are breastfeeding, contact us when you receive your appointment letter, so we can give you more information before you come for your injection.

During a breast sentinel lymph node injection

You will meet our team of technologists or radiographers and they will explain the procedure to you. You can ask any questions about the injection.

You will be injected in the affected breast with a tracer. This is a radioactive fluid that helps the surgeon to see your lymph nodes clearly. We will only ask you to uncover the breast that you are having the surgery on.

As soon as the injection is done, we will leave a small dressing on your breast and you can get dressed again. The procedure takes less than 5 minutes.

During your operation the surgeons will use a special probe that detects the radioactive tracer, and shows where the sentinel lymph node is.

Pregnancy and breastfeeding

As the procedure involves an injection of a radioactive tracer, you must tell us if:

  • you are pregnant
  • you think you might be pregnant
  • you are breastfeeding

Tell us as soon as you receive your appointment, if possible.

For all nuclear medicine tests we check your pregnancy status with you before using any radioactive tracer.

Pain during the injection

The injection of radioactive tracer is given into your breast. This might be painful for a moment, but this soon disappears.

After the injection

There are no side effects from this injection and you can carry on with your normal activities.

After the injection you will have some radioactivity in your body, but this is not a risk to you or other people around you.

Risks of breast sentinel node injection

We make sure the amount of radiation you receive is as small as possible.

You can read government information about radiation exposure from medical imaging.

The tracer is made from specially-treated human albumin (a protein taken from screened blood donations).

It's perfectly safe for you to travel abroad after your injection, but many airports and sea ports are now equipped with very sensitive radiation detectors. It is possible that the very small amount of radioactivity left in your body could set off a detector as you pass through security. If you plan to travel abroad in the week after your injection, it could be helpful to take your appointment letter with you.

Resource number: 5364/VER1
Last reviewed: June 2023
Next review due: June 2026

Trusted Information Creator. Patient Information Forum

Contact us

If you have any questions about your test in the nuclear medicine department, please contact us.

Phone 020 7188 4112, Monday to Friday, 9am to 5pm

Email [email protected]

Do you have any comments or concerns about your care?

Contact our Patient Advice and Liaison Service (PALS)

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