Spinal fluid tubes are properly labeled with the patient’s name and medical record number and identified with sequential numbers: #1, #2, #3, and #4. Default testing for each tube is as follows:
#1 Cell counts (appearance, color, RBC, nucleated cells)
#2 Cultures (viral, bacterial)
#3 Chemical tests (glucose, lactate, LDH, protein, etc.)
#4 Cell counts/other (repeat cell count especially if #1 is bloody, additional volume for repeat or additional testing such as VDRL, oligocolonal banding, West Nile virus serology, and others)
Ideally, CSF specimens should consist of these four (4) tubes each containing 2-3 ml of fluid. This will provide enough sample to perform multiple tests with adequate volume for repeat analysis and add-on tests. To ensure the best patient care, if at all possible, CSF samples should be submitted in this manner.
Under extreme circumstances, a bare minimum of two (2) tubes each containing 2-3 ml of CSF can be submitted. This often provides sufficient sample to perform chemical tests, cell counts and culture though, depending on the exact volume submitted, the laboratory cannot guarantee the ability to perform every ordered test. Tests ordered for which there is not enough CSF to perform the test will be resulted as “quantity not sufficient for analysis” (QNS). In addition, submitting fewer than four tubes will necessitate that a single sample be shared among multiple laboratory departments which may increase the result turnaround time.
If a less than ideal volume of CSF is submitted you may wish to indicate which tests are a priority for your patient (i.e. “please perform cell count first”) and the laboratory will direct the sample accordingly.
Orders received without tube number specification will be ordered by the laboratory as described below:
|Default tube numbers for type of testing|
|Number of tubes submitted||4 tubes||3 tubes||2 tubes*||1 tube*|
|Chemistry (glucose, lactate, LDH, protein, etc)||3||3||1||1|
|Cultures (bacterial, viral)||2||2||2||1|
|Cell Count (appearance, color, RBC, nucleated cells)||1 and 4||1 and 3||2||1|
|Other (oligoclonal banding, VDRL, etc.||4||1||1||1|
*It is inadvisable to submit one or two tubes only if more are possible. Indicate order of preference for tests requested.