A sentinel lymph node
biopsy is a surgery that takes out
lymph node tissue to look for cancer. A sentinel node
biopsy is used to see if a known
cancer has spread from the original cancer site. A
sentinel node biopsy may be done instead of a more extensive surgery called
lymph node dissection. But if cancer is found in the sentinel lymph node at the
time of surgery, more surgery may be needed to remove additional lymph
The sentinel lymph node is the first node in a group of
nodes in the body where cancer cells may move to after they have left the
original cancer site and started to spread. For example, the sentinel node (SN)
for breast cancer is normally one of the lymph nodes under
Your doctor injects a blue dye or special tracer
substance or both into the area around the original cancer site. The dye or
tracer moves to the first lymph node (sentinel node) that drains close to the
cancer site. The dye or tracer makes a map pattern of lymphatic fluid. The map
can show where the cancer is likely to spread and which lymph node is most
likely to have cancer cells. Your doctor can see the dye or tracer with a
special device. The lymph node can be taken out, cut into very thin slices, and
looked at under a microscope at the time of surgery. If a sentinel node is
positive for cancer cells, more surgery may be needed to remove more lymph
Other tests, such as a
culture, genetic tests, or immunological tests, may be
done on the lymph node sample.
Why It Is Done
A sentinel lymph node biopsy is done
See if a known cancer, such as breast cancer or
melanoma, has spread to the lymph nodes.
Remove a few lymph nodes
instead of removing all the lymph nodes in an area. If the sentinel lymph node
does not have cancer, this surgery takes less time, is simpler to do, and has a
lower chance of long-term problems, such as ongoing swelling of an arm or leg (lymphedema).
How To Prepare
Tell your doctor if you:
Are or might be pregnant.
taking any medicines, especially medicines for depression, such as paroxetine (Paxil), fluoxetine (Prozac), amitriptyline (Limbitrol), or venlafaxine (Effexor).
Are allergic to any medicines, including any
anesthetics or dyes.
Have had bleeding
problems or take blood-thinners, such as aspirin or warfarin
Have had a biopsy in the past.
radiation treatment to the biopsy site.
Follow your doctor's instructions carefully. If you are
given a medicine (sedative) to make you relax or sleep
before the biopsy, do not eat or drink for 8 hours before the biopsy. Arrange
for someone to drive you home after the biopsy.
Talk to your
doctor about concerns you have regarding the need for the test, its risks, how
it will be done, or what the results may mean. To help you understand the
importance of this test, fill out the
medical test information form(What is a PDF document?).
How It Is Done
You will need to take off clothing near
the biopsy site. You will wear a gown for a covering during the test.
If you are very anxious about the biopsy, you may be given a medicine
(sedative) to help you relax.
Before a sentinel node biopsy is
done, the dye or tracer is injected into the area, and a special camera
(lymphoscintigraphy) takes pictures of the lymph nodes. Some doctors use pain medicine with the dye to reduce discomfort. The dye may turn your
skin blue for a few days after the biopsy.
The first lymph node or
nodes to absorb the tracer are called the sentinel nodes. This node or nodes
and the tissue around them are taken out. You may have a numbing medicine
(local anesthesia) or go to sleep for the biopsy. The
lymph node sample is cut into many thin slices and looked at under a microscope
for cancer. You will have some stitches and a bandage over the biopsy site.
A sentinel lymph node biopsy usually takes 30 to 60 minutes but
may take longer. If you have general anesthesia, you will be watched by a nurse
in the recovery room until you are fully awake.
Your doctor will
give you specific instructions to take care of your biopsy site. During your
follow-up visit, your doctor will discuss the results of your biopsy with you
and take out your stitches.
How It Feels
You may feel a sharp sting or burn from
the medicine used to numb the biopsy site or from the dye or tracer. Feeling
pressure or warmth during the biopsy is normal, but you should feel little or
no pain. If you have pain, tell your doctor. If you feel like you are having an
allergic reaction, tell your doctor. This can happen
with the dye used for this biopsy.
If you have general anesthesia, you
may feel drowsy for several hours after the biopsy. You may have a mild sore
throat from the tube used to help you breathe during the biopsy. Throat
lozenges and gargling with warm salt water may help soothe your sore throat.
You may get medicine at the biopsy site that will help with the pain for 6 to
12 hours. You may have more pain after this medicine wears off.
The biopsy site may be sore for several days. A small amount of bleeding
is normal. Ask your doctor how much drainage to expect. Call your doctor
immediately if you have:
An increase in pain, redness, or swelling at
the biopsy site.
An increase in bleeding or
drainage, such as pus.
Any swelling in your arm.
It is possible to have some problems after a
biopsy. Your doctor will give you instructions on what to do if a problem
Bleeding from the biopsy site. This risk is
higher for people who have bleeding problems or who take blood-thinning
medicines. If you are at risk for bleeding, you may be given blood clotting
factors before the biopsy.
Skin numbness at the biopsy
Infection at the biopsy site
Swelling and fluid
buildup (lymphedema). This is less likely after a sentinel node biopsy
than if more lymph nodes are taken out (axillary
Problems from general anesthesia, if it is
Damage to nerves at the biopsy site. This may cause weakness
lymph node tissue is usually treated with special dyes (stains) that color the
cells so problems can be clearly seen.
Sentinel lymph node biopsy
The dye or tracer flows evenly to the
sentinel lymph node.
The lymph node has normal numbers of lymph
The structure of the lymph node and the
cells look normal.
No cancer is present.
The dye or tracer does not flow evenly to
the sentinel lymph node.
The sentinel lymph node cannot be
Cancer cells may be seen. Cancer cells may
start in the lymph nodes, such as in
Hodgkin's lymphoma. Cancer cells may have spread, or
metastasized, from other sites, such as in
breast cancer or
What Affects the Test
It may not be possible to have a
clear result from the small sample taken during a sentinel lymph node biopsy.
Surgery to remove more lymph nodes (axillary dissection) may be
What To Think About
In a sentinel lymph node biopsy, less tissue is
taken out but more sections of tissue are looked at than by a standard lymph
node dissection. But if cancer is found, additional surgery may be needed to
look at more lymph nodes.
Swelling in the area around the
biopsy site is less common with sentinel lymph node biopsy than with a lymph
The dye may cause your skin to be blue for several
days after the biopsy. It may also cause your urine to turn green for 1 to 2
It is possible to have
false-negative results from the small sample taken
during a sentinel lymph node biopsy.
Other Works Consulted
American Cancer Society (2010). Breast Cancer: Treating Breast Cancer. Available online: http://www.cancer.org/Cancer/BreastCancer/DetailedGuide/breast-cancer-treating-general-info.
Cody HS (2010). Axillary dissection. In JR Harris et al., eds., Diseases of the Breast, 4th ed., pp. 562–569. Philadelphia: Lippincott Williams and Wilkins.
National Cancer Institute (2011). Sentinel Lymph Node Biopsy. Available online: http://www.cancer.gov/cancertopics/factsheet/detection/sentinel-node-biopsy.
Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby.
ByHealthwise Staff Primary Medical ReviewerSarah Marshall, MD - Family Medicine Specialist Medical ReviewerC. Dale Mercer, MD, FRCSC, FACS - General Surgery
How this information was developed to help you make better health decisions.