What is one method to determine if post-craniotomy drainage is cerebrospinal fluid (CSF)?

The presence of glucose in a drainage sample is a key indicator that the fluid may be cerebrospinal fluid (CSF). This is because CSF contains a higher concentration of glucose when compared to most other bodily fluids. When a sample from post-craniotomy drainage is obtained, testing for glucose levels can help differentiate between CSF and other potential drainage fluids, such as serum or serous fluid. In CSF, glucose levels are typically elevated relative to those found in blood plasma, making this a reliable test.

Other methods, while they can provide some information, are not as definitive as measuring glucose levels. For example, assessing color clarity may just inform one about the physical characteristics of the fluid but does not identify its biochemical properties. Similarly, testing for acidity may not show significant differences between CSF and other fluids, and measuring specific gravity tends to be less specific for CSF identification. Therefore, glucose testing stands out as a critical and effective method for determining if drainage is indeed cerebrospinal fluid.