A nurse is assisting during a lumbar puncture.
How should the nurse position the patient for this procedure?

Choice A rationale

Measurement of post-void residual (PVR) urine volume is a valid indication for catheterization. This procedure assesses bladder emptying efficiency, particularly in patients experiencing urinary symptoms like hesitancy or incomplete voiding. Elevated PVR volumes (typically > 100 mL) can indicate outflow obstruction or bladder dysfunction, necessitating further investigation.

Choice B rationale

Relief of urinary retention is a primary indication for catheterization. Acute urinary retention, often caused by prostatic enlargement or neurologic dysfunction, results in painful bladder distention and potential renal compromise. Catheterization promptly drains the bladder, alleviating discomfort and preventing upper urinary tract damage by reducing intravesical pressure.

Choice C rationale

Routine acquisition of a urine specimen is generally not an indication for catheterization. Clean-catch midstream urine samples are typically sufficient for most diagnostic purposes, minimizing the risk of catheter-associated urinary tract infections (CAUTIs). Catheterization is invasive and should be reserved for situations where a clean voided specimen is unobtainable or specific sterile collection is required.

Choice D rationale

Convenience for nursing staff or the patient's family is not a legitimate medical indication for urinary catheterization. Catheterization is an invasive procedure associated with significant risks, including CAUTIs, urethral trauma, and patient discomfort. Its use should be medically justified and limited to situations where benefits clearly outweigh the potential harms, prioritizing patient safety.

Choice E rationale

An open perineal wound is a strong indication for urinary catheterization. Catheterization diverts urine away from the wound, preventing contamination and promoting optimal healing. Urine is inherently acidic and can introduce bacteria, impairing tissue repair and increasing infection risk in compromised perineal tissues, making diversion crucial for wound management.

Choice A rationale

Prone positioning with the head turned is not suitable for a lumbar puncture because it makes it difficult to achieve adequate lumbar flexion, which is crucial for widening the intervertebral spaces. This position also makes patient monitoring and access to the spinal column challenging for the procedure.

Choice B rationale

Supine positioning, even with knees raised, does not provide the necessary spinal flexion required to open the intervertebral spaces. The goal of patient positioning for a lumbar puncture is to maximize the separation between the vertebral laminae for needle insertion.

Choice C rationale

The lateral recumbent position with the chin resting on flexed knees (fetal position) maximizes the flexion of the spine. This flexion widens the intervertebral spaces between the lumbar vertebrae, facilitating easier and safer insertion of the spinal needle into the subarachnoid space for cerebrospinal fluid collection.

Choice D rationale

Prone positioning, even with one leg flexed, does not adequately flex the lumbar spine to separate the vertebrae. Proper positioning is paramount for successful and safe needle insertion into the cerebrospinal fluid space during a lumbar puncture, which this position does not achieve.