Ultrasound Evaluation of Two Anatomic Landmarks in Spinal Anesthesia for Cesarean Section: the Posterior Superior Iliac Spine VS Iliac Crest (USPSISICL)

The Third Affiliated Hospital of Guangzhou Medical University

Status: Enrolling

Conditions: Spinal Anesthesia; Ultrasonography; Posterior Superior Iliac Spine; Intercristal Line

Study type: Observational

Funder types: Other

Identifiers

NCT06711601

[2024] No. 131

Details and patient eligibility

About

Intercristal line as palpation landmarks to identifying the vertebral level is frequently inaccurate.To find more safe and reliable body surface markers and convenient methods to be solved in clinical work.The investigators performed a two-stage study to evaluated the accuracy of intercristal line and the The Posterior Superior Iliac Spine (PSIS) line to identify the lumbar interspinous spaces for spinal anesthesia using ultrasonography in pregnant woman which will provide a second option.

Full description

The investigators performed a two-stage study to evaluated the accuracy of Intercristal line and the PSIS line to identify the lumbar intervertebral space for spinal anesthesia using ultrasonography in pregnant woman. In phase 1, the distances between the PSIS line and each lumbar interspinous space is measured by ultrasound,and the mean and 95% confidence interval of distances in pregnant women with different height ranges were calculated to provide a reference for identifying specific lumbar spaces.In phase 2, a further 230 participants were received the PSIS, Intercristal line or both as palpation landmarks to define specific lumbar spaces.

Enrollment: 660 estimated patients

Sex: Female

Volunteers: No Healthy Volunteers

Inclusion criteria

• After obtaining written informed consents,pregnant women at 37-42 weeks of gestation

Exclusion criteria

• BMI ≥ 40 kg/m² (to minimize palpation variability), History of lumbar surgery/deformity (scoliosis, spondylolisthesis or osteoporotic vertebral collapse), Inability to maintain the flexed lateral decubitus position, Participant withdrawal, Unforeseen anatomical anomalies discovered during screening.

Trial design

660 participants in 3 patient groups

T group

Description:

The intercristal line-based palpation protocol followed the rule described by Kim et al\[19\], with minor modifications to accommodate the flexed lateral decubitus position: Select the interspinous space that is either intersected by the intercristal line or lies immediately below it.

P group

Description:

The PSIS line-based palpation protocol stipulated targeting the L3/4 interspinous space within the an interval using hierarchical rules: single spaces are labeled L3/4; for two spaces, L3/4 is the intercristal line-intersected one (or lower if neither); for rare three spaces, the lowest is L3/4

Group M

Description:

Based on an interim analysis of Phase 1 data, we established the following decision protocol for L3/4 interspinous space localization: 1. PI ≥9 cm: Select the interspace at or immediately below the PI line. 2. PI ≤7 cm: Select the interspace at or immediately above the PI line. 3. PI 7-9 cm: Apply a 6.5-10 cm target window from the PSIS point. * If one interspace lies within this window, select it. * If multiple interspaces are present, choose the most caudal one.