Skip to main content

Breast Cancer Sentinel Lymph Node Biopsy


What you need to know about a sentinel lymph node biopsy (SLNB):

A sentinel lymph node (SLN) is usually the lymph node closest to the breast tumor. It is usually found in the armpit, or along the sternum (breastbone) or collarbone. A biopsy is a procedure used to find and remove a SLN. During the biopsy, the SLN will be tested for cancer cells. If the test is positive, it may mean that breast cancer has spread outside of your breast. This information can help your healthcare provider decide what other treatments you need.

How to prepare for a SLNB:

  • You may need a nuclear scan before your procedure. During a nuclear scan, healthcare providers will inject a small amount of radioactive liquid in your breast. Radioactive liquid will move to the location of your lymph nodes and help them show up better in pictures. A camera will take pictures of the lymph nodes. The pictures will help your healthcare provider plan for your procedure.
  • Your healthcare provider will talk to you about how to prepare for your procedure. He or she may tell you not to eat or drink anything after midnight on the day of your procedure. He or she will tell you what medicines to take or not take on the day of your procedure. You may be given contrast liquid during your biopsy. Tell your healthcare provider if you have ever had an allergic reaction to contrast liquid. Arrange for someone to drive you home and stay with you after your procedure.

What will happen during a SLNB:

  • You may be given an antibiotic through your IV to help prevent a bacterial infection. Tell the healthcare provider if you have ever had an allergic reaction to an antibiotic. You may be given general anesthesia to keep you asleep and free from pain during your procedure. You may instead be given local anesthesia to numb the area. With local anesthesia, you may still feel pressure or pushing during the procedure, but you should not feel any pain.
  • Your healthcare provider will inject blue contrast liquid, radioactive liquid, or both near the tumor. The liquid will move to the SLN. Your healthcare provider may use an instrument to help find the SLN. He or she will do this by gently moving an instrument over your skin. The instrument will show pictures of the SLN on a monitor. Your healthcare provider will make a small incision in the skin that covers the SLN. The incision is usually in your armpit or chest. The SLN will be removed and checked for cancer cells. If cancer is found, your healthcare provider may remove several more lymph nodes for testing. Your incision may be closed with stitches or strips of medical tape and covered with a bandage.

What will happen after a SLNB:

Healthcare providers will monitor you until you are awake. You may be able to go home after you are awake and your pain is controlled. Your urine or bowel movement may be blue for 24 to 48 hours after your procedure. This is caused by the blue contrast liquid given to you during the procedure. You may have bruising or swelling at the biopsy site. This is normal and expected. The arm closest to the biopsy site may be sore. This should get better within 48 to 72 hours.

Risks of a SLNB:

You may bleed more than expected or get an infection. You may develop a condition called lymphedema. Lymphedema is tissue swelling in your arm nearest to where the SLN was removed. You may have long-term pain or discomfort in your arm. Your skin in the arm may be permanently thick or hard. Your nerves may be damaged during your procedure. This may cause numbness or tingling in your arm. It may also cause difficulty moving your arm. You may have an allergic reaction to the contrast liquid. This may require medicine or other treatments.

Seek care immediately if:

  • Blood soaks through your bandage.
  • Your stitches come apart.
  • Your bruise suddenly gets larger and feels firm.

Call your doctor if:

  • You have a fever or chills.
  • Your wound is red, swollen, or draining pus.
  • You have nausea or are vomiting.
  • Your skin is itchy, swollen, or you have a rash.
  • Your pain does not get better after you take medicine for pain.
  • You have questions or concerns about your condition or care.


You may need any of the following:

  • NSAIDs , such as ibuprofen, help decrease swelling, pain, and fever. This medicine is available with or without a doctor's order. NSAIDs can cause stomach bleeding or kidney problems in certain people. If you take blood thinner medicine, always ask your healthcare provider if NSAIDs are safe for you. Always read the medicine label and follow directions.
  • Acetaminophen decreases pain and fever. It is available without a doctor's order. Ask how much to take and how often to take it. Follow directions. Read the labels of all other medicines you are using to see if they also contain acetaminophen, or ask your doctor or pharmacist. Acetaminophen can cause liver damage if not taken correctly. Do not use more than 4 grams (4,000 milligrams) total of acetaminophen in one day.
  • Prescription pain medicine may be given. Ask your healthcare provider how to take this medicine safely. Some prescription pain medicines contain acetaminophen. Do not take other medicines that contain acetaminophen without talking to your healthcare provider. Too much acetaminophen may cause liver damage. Prescription pain medicine may cause constipation. Ask your healthcare provider how to prevent or treat constipation.
  • Take your medicine as directed. Contact your healthcare provider if you think your medicine is not helping or if you have side effects. Tell him or her if you are allergic to any medicine. Keep a list of the medicines, vitamins, and herbs you take. Include the amounts, and when and why you take them. Bring the list or the pill bottles to follow-up visits. Carry your medicine list with you in case of an emergency.

Care for your incision wound as directed:

Ask your healthcare provider when your wound can get wet. Carefully wash around the wound with soap and water. It is okay to let soap and water gently run over your wound. Do not scrub your wound. Gently pat dry the area and put on new, clean bandages as directed. Change your bandages when they get wet or dirty. If you have strips of medical tape, let them fall of on their own. It may take 10 to 14 days for them to fall off. Check your wound every day for signs of infection, such as redness, swelling, or pus. Do not put powders or lotions on your wound. If lymph nodes have been taken from your armpit, ask your healthcare provider when you can wear deodorant.


  • Apply ice on your wound for 15 to 20 minutes every hour or as directed. Use an ice pack, or put crushed ice in a plastic bag. Cover it with a towel before you apply it to your skin. Ice helps prevent tissue damage and decreases swelling and pain.
  • Elevate your arm nearest to the biopsy site as often as you can. This will help decrease swelling and pain. Prop your arm on pillows or blankets to keep it elevated above the level of your heart comfortably.

  • Do not do strenuous activities for 24 to 48 hours. Strenuous activities include heavy lifting, sports, or running. If lymph nodes were taken from your armpit, do not push or pull with your arm. These activities may put too much stress on your wound. Rest and take short walks around the house. Ask your healthcare provider when you can return to your normal activities.
  • Drink plenty of liquids as directed. This will help flush out contrast liquid from your body. Ask how much liquid to drink each day and which liquids are best for you.

Ask your healthcare provider how to prevent lymphedema and infection:

Lymphedema is fluid buildup in fatty tissues under your skin. Lymphedema may happen in the arm closest to where lymph nodes were removed. An infection in your skin can make lymphedema worse. Ask your healthcare provider how you can decrease your risk for skin infections and lymphedema.

Follow up with your doctor as directed:

Write down your questions so you remember to ask them during your visits.

© Copyright IBM Corporation 2021 Information is for End User's use only and may not be sold, redistributed or otherwise used for commercial purposes. All illustrations and images included in CareNotes® are the copyrighted property of A.D.A.M., Inc. or IBM Watson Health

The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.