Related Experiment Video
Updated: Jun 6, 2026

Spinal Sonography for Ultrasound-Guided Lumbar Neuraxial Anesthesia
Published on: January 31, 2025
Can parturients identify the midline during neuraxial block placement?
Bridget M Marroquin1, Karamarie Fecho, Victoria Salo-Coombs
1Department of Anesthesiology, University of North Carolina at Chapel Hill, CB #7010, Chapel Hill, NC 27599-7010, USA.
Study Objective:
To determine whether parturients can reliably identify their midline during epidural or spinal needle insertion, and to determine whether parturient feedback helps the anesthesiologist successfully identify the midline.
Design:
Survey instrument completed by anesthesiologists.
Setting:
Labor and delivery unit of a university-based, tertiary-care hospital.
Measurements:
Completed questionnaires were obtained for 554 of 904 (61.3%) neuraxial blocks. Data were collected on the type of neuraxial block, number of needle redirections required to identify the midline, the patient's height and weight, the patient's position during block placement, whether the patient was questioned for assistance identifying the midline, and if so, how helpful the patient was in redirecting the needle to locate the epidural or subarachnoid space.
Main Results:
The anesthesiologist requested the assistance of 194 patients (35.0%) for needle location. Of those questioned, the anesthesiologist reported 128 instances (66.0%) when the patient's response was helpful in identification of the midline. Morbidly obese parturients (BMI > 35 kg/m²) were questioned more often than their non-morbidly obese counterparts (48.9% vs. 30.5%; P < 0.0005). Of those morbidly obese parturients who were questioned (n = 64), 76.6% were reported by the anesthesiologist to be helpful.
Conclusions:
Most patients, including morbidly obese patients, are helpful in identifying the midline during neuraxial anesthesia.
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