During the Procedure

Sentinel node biopsy is usually performed at the same time that a lumpectomy is performed. If this is the case, the sentinel node biopsy is usually performed first.

Depending on the preference of the doctor, the blue dye or radioactive tracer may be injected after the woman has received anesthesia. The surgeon then uses a handheld Geiger counter to determine the exact location of the sentinel lymph node and makes a small incision over that point. If the patient has been injected with blue dye, the sentinel lymph node is colored blue. This provides the surgeon with visual confirmation of the sentinel node.

The surgeon then removes an average of two to three sentinel lymph nodes for examination under a microscope. Depending on the surgeon's practice and suspicion, a pathologist may do a quick test after freezing the material (known as a frozen section) to examine these nodes for cancer while the surgeon performs the lumpectomy or the mastectomy. If cancer cells are found in the sentinel lymph node, either at the time of surgery or when the final report from the pathologist is available, the surgeon then performs an axillary lymph node dissection.

A sentinel node biopsy typically takes about 45 minutes to perform. If a lumpectomy is also being performed, an extra 30-45 minutes are usually added to the total surgery time.