Ultrasound-assisted vs Palpation-guided Lumbar Punctures

Lumbar puncture (LP) is a commonly performed diagnostic and therapeutic procedure. The standard approach relies on palpation of surface anatomical landmarks to identify an appropriate intervertebral space for needle insertion. When landmarks are difficult to identify, LP may require multiple needle insertions or redirections, cause greater patient discomfort, delay cerebrospinal fluid (CSF) collection, or require a subsequent image-guided procedure.

Point-of-care ultrasound can be used before needle insertion to identify the spinal midline and an appropriate interspinous space and to estimate the depth to the target. Previous studies of ultrasound-assisted LP have produced variable findings regarding procedural success, efficiency, traumatic tap, and patient discomfort. Patient-centered complications, including post-dural puncture headache, have been less extensively evaluated.

This is a prospective, multicenter, parallel-group randomized controlled trial involving adults undergoing a clinically indicated LP in an inpatient or outpatient setting. Participants will be randomly assigned in a 1:1 ratio to pre-procedural ultrasound localization or standard palpation of anatomical landmarks.

In the ultrasound-assisted group, point-of-care ultrasound will be used before needle insertion to identify the spinal midline and interspinous space and estimate the depth to the target. The selected insertion site will then be marked, and the LP will proceed using standard technique; the needle will not be advanced under real-time ultrasound guidance. In the standard palpation group, the insertion site will be identified by palpation without pre-procedural ultrasound. Other aspects of the procedure and post-procedure care will follow standard clinical practice at each participating site.

The trial will determine whether pre-procedural ultrasound localization improves first-needle insertion success and reduces procedural burden and complications compared with standard palpation.

Inclusion criteria

• Adults aged 18 years old and above
• Patients requiring lumbar puncture for diagnostic or therapeutic purposes as determined by the treating physician
• Must be able to give informed consent, or if unable, have a legally authorized representative provide written consent

Exclusion criteria

• Inability to safely undergo bedside lumbar puncture (either ultrasound-guided or palpation guided) as determined by the treating physician
• Known contraindications to lumbar puncture, including:
• Increased intracranial pressure with risk of herniation
• Infection at the lumbar puncture site
• Known coagulopathy or platelet count <50,000 µL
• Received DVT prophylaxis on the day of planned lumbar puncture