During a lumbar puncture, which position is commonly used for the patient?

• A. Lateral recumbent position with knees flexed toward the abdomen
• B. Supine with legs straight
• C. Prone with head turned to the side
• D. Seated upright with back curved

Answer: (A)

Positioning for a lumbar puncture is chosen to maximize the space between lumbar vertebrae and keep the spine stable so the needle can reach the subarachnoid space safely. Placing the patient in the lateral recumbent posture with knees drawn toward the abdomen places the spine in full flexion, which opens the interlaminar spaces between the vertebrae (especially around L3–L5) and aligns the landmarks for needle insertion between those levels. This posture also reduces movement and makes it easier to palpate the correct interspace while maintaining a comfortable, stable position for the procedure and any opening pressure measurement.

Other positions don’t provide the same optimal opening of the spaces or stability. Lying supine with legs straight leaves the spine less flexed, making needle entry more challenging. Prone with the head turned to the side isn’t a typical approach for accessing the lumbar subarachnoid space and can hinder correct needle placement. A seated upright position with the back curved can be used in some settings, but the lateral recumbent method is commonly taught and preferred for ease of access and patient comfort during CSF collection.