Canadian Society for Medical Laboratory Science (CSMLS) Practice Exam

What type of fluid is obtained during a lumbar puncture?

1. Cerebrospinal fluid

2. Blood plasma

3. Serous fluid

4. Peritoneal fluid

The correct answer is: Cerebrospinal fluid

During a lumbar puncture, the primary purpose is to collect cerebrospinal fluid (CSF). This procedure involves inserting a needle into the lower back, specifically into the subarachnoid space surrounding the spinal cord. The CSF serves several critical functions, including providing cushioning for the brain and spinal cord, maintaining intracranial pressure, and facilitating the circulation of nutrients and waste. Cerebrospinal fluid is distinct from other fluid types due to its unique composition and location. For instance, blood plasma is the liquid component of blood that carries cells, nutrients, and waste — it is not collected during a lumbar puncture. Serous fluid, found in body cavities, plays a role in reducing friction between organs, while peritoneal fluid is found in the abdominal cavity and serves a different purpose related to the organs there. Thus, the identification of cerebrospinal fluid as the fluid obtained during this procedure reflects its important diagnostic value in assessing neurological conditions.