How much cerebro spinal fluid is removed during lumbar puncture ?

3-5 cc: Usually routine analysis necessitates between 3 to 5 cc. This is about half a teaspoon to one teaspoon. Some conditions necessitate removing 2 teaspoons and in rare conditions such as hydrocephalus, 20-30 cc may be removed.

Usually not much: For a typical diagnostic tap, a total volume of 20-25cc is typical (less than two tablespoons), but some tests, such as cytology, require larger amounts of fluid. When doing a tap to reduce the CSF pressure (a therapeutic tap), much larger volumes can be removed.