Diagnostic Procedures

Lumbar Puncture

A procedure in which a thin, hollow needle is inserted into the lower part of the spine to collect a sample of cerebrospinal fluid (CSF), also called spinal tap or LP. This is done by placing the needle between two bones in the spine and into the subarachnoid space (the fluid-filled space between the thin layers of tissue around the spinal cord). After the CSF sample is removed, it is checked under a microscope for signs of infection, inflammation, or diseases, such as cancer or certain nervous system conditions. A lumbar puncture may also be done to measure or reduce CSF pressure around the spinal cord and brain, to inject drugs, such as chemotherapy or anesthesia drugs, directly into the CSF, or to inject contrast dye for certain imaging tests. (NCI Dictionary of Cancer Terms)

Lumbar punctures are not treatment. For CoC hospitals, this procedure should be coded in the “Surgical Diagnostic and Staging Procedure [NAACCR #1350].” SEER does not collect this data item, so this procedure would not be coded for the SEER registries.

Open Biopsy

An open biopsy is done for tumors that are easily be removed by surgery. A part of the skull is removed (a craniotomy), a sample of the brain tissue is removed. Frequently the tissue is inspected and if the tumor is malignant, a surgical resection may be done while the skull is still open.

The open biopsy is not coded as treatment; however, the surgical resection would be coded as treatment if it was done.

Stereotactic Biopsy

Stereotactic biopsies are commonly used for tumors that may be hard to reach in the brain. The biopsy uses a computer and 3-dimensional (3-D) scanning to find the tumor and then guide the needle to remove the tissue.

A small incision is made in the scalp, and a small hole is drilled through the skull. A biopsy needle is inserted through the hole to remove cells or tissues.

The main purpose of the stereotactic biopsy is to extract tissue to determine the histology.

For many years, CoC hospitals have coded the stereotactic biopsy in the data item “Surgical Diagnostic and Staging Procedure [NAACCR #1350].” However, for SEER, which does not require the data item “Surgical Diagnostic and Staging Procedure,” has instructed their registries to record this procedure in the data item “Surgery of Primary Site 2023 [NAACCR #1291]” as a local tumor excision/excisional biopsy, even though this is not a surgical procedure.

Starting in 2027, SEER will be changing this rule.

• Biopsies of the brain, specifically stereotactic biopsies, are not to be recorded in “Surgery of Primary Site 2023 [NAACCR #1291]”
• This will be effective for cases with a diagnosis date of 1/1/2027 or later.
• For cases diagnosed prior to 1/1/2027, follow the current instructions, which state to code a stereotactic biopsy as a local excision
  • See the 2026 (or prior) SEER Manual, Appendix C: Site-Specific Coding Manuals, Brain

For CoC registrars in SEER regions, for cases diagnosed prior to 1/1/2027, code both the Surgical Diagnostic and Staging Procedure data item to meet CoC standards and Surgery of Primary Site data item to meet SEER standards.

• For cases diagnosed 1/1/2027 and later, code only the Surgical Diagnostic and Staging Procedure data item.
• Reminder: This instruction applies to biopsies (specifically Stereotactic biopsies) of the Brain/CNS only.

Updated: September 23, 2026