Final answer:
A lumbar puncture is performed with the patient in the fetal position in the lower lumbar area of the vertebral column to reduce the risk of injuring the central tissue of the spinal cord, at a safe level like L3-L4 or L4-L5.
Step-by-step explanation:
The true statement about a lumbar puncture is D) It is done with the patient in the "fetal" position. A lumbar puncture, or spinal tap, involves inserting a needle into the lower lumbar area of the vertebral column to withdraw cerebrospinal fluid (CSF) for testing. This area is chosen because the spinal cord does not extend through the lower lumbar region, thus minimizing the risk of damaging the central tissue of the spinal cord.
Performing the lumbar puncture in the lower lumbar area is safer because the procedure avoids the central nervous tissue which ends above this region, and only the nerve roots, known as the cauda equina, are present here.
The patient is often placed in the fetal position because it helps to widen the spaces between the vertebral bones, making it easier to access the subarachnoid space where CSF can be safely withdrawn. The correct level for a lumbar puncture is typically between the third and fourth or the fourth and fifth lumbar vertebrae (L3-L4 or L4-L5).