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

Ultrasound Evaluation Of Two Anatomic Landmarks In Spinal Anesthesia For Cesarean Section: The Posterior Superior Iliac Spine vs Iliac Crest

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.

Study Overview

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

Detailed 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.

• Study Type: Observational
• Enrollment (Estimated): 660

Contacts and Locations

• Study Contact: Name: Wenhua Zhang, PhD; Phone Number: +86 13611453199; Email: zhangcobra@126.com

Study Locations

• China
  • Guangdong
    • Guangzhou, Guangdong, China
      • Recruiting
      • The Third Affiliated Hospital of Guangzhou Medical University
      • Contact: Souping Wang; Phone Number: +86 18988910585; Email: 849412396@qq.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Probability Sample

Study Population

We enrolled parturients aged 22-45 years at 37-42 weeks of gestation scheduled for epidural or combined spinal-epidural anesthesia (for labor or cesarean section)

Description

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.

Study Plan

How is the study designed?

Number of groups / cohorts

3

Cohorts and Interventions

Group / Cohort
T group; 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; 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; Based on an interim analysis of Phase 1 data, we established the following decision protocol for L3/4 interspinous space localization: PI ≥9 cm: Select the interspace at or immediately below the PI line.; PI ≤7 cm: Select the interspace at or immediately above the PI line.; 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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The distance between the PSIS line and each mid-interspinous space	PSIS line was defined as an intercristal line drawn between the the final posterior superior iliac spine point.Use a ruler to measure the distance between the PSIS line and each midddle- interspinous space （L1/2 through L5/S1）and record. The mean of distances and 95% confidence interval are calculated.	three days
The accuracy of the anatomic landmarks to determine the L3/4 interspinous space	The L3-L4 intervertebral space was detected using intercristal line and the PSIS line in a random order by 2 experienced anesthesiologists. After determining the L3-L4 intervertebral space using each method alternately, horizontal skin marks were created with an erasable pen. Then, another experienced anesthesiologist for ultrasonographic examination assessed the intervertebral spaces.After identifying the sacrum, the investigator moved the probe in a cephalad direction, counted the intervertebral spaces and assessed the actual intervertebral spaces of the 2 skin marks.	three days

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
baseline data	The age	three days
baseline data	body mass index (BMI)	three days
baseline data	waist circumference	three days
baseline data	the gestational weeks	three days
The distance between the palpated intercristal line and PSIS line	palpated intercristal line line was identified and marked by bilateral palpation of the iliac crest summits. Subsequently, two reference points were defined: "point PSIS" (intersection of the PSIS line with the spinal midline) and "point PI" (intersection of the PI line with the spinal midline). We then calculated the following three distances: the "L3/4 distance" (from the L3/4 interspinous space midpoint to point PSIS), the "PI distance" (from point PI to point PSIS) The experienced anesthesiologist for ultrasonographic examination assessed the actual interspinous space of the intercristal line.	three days
Maternal height	Maternal height	three days

Collaborators and Investigators

• Sponsor: The Third Affiliated Hospital of Guangzhou Medical University
• Investigators: Study Director: Souping Wang, PhD, The Third Affiliated Hospital of Guangzhou Medical University

Study record dates

Study Major Dates

• Study Start (Actual): October 10, 2024
• Primary Completion (Actual): December 30, 2025
• Study Completion (Estimated): January 23, 2026

Study Registration Dates

• First Submitted: November 18, 2024
• First Submitted That Met QC Criteria: November 26, 2024
• First Posted (Actual): December 2, 2024

Study Record Updates

• Last Update Posted (Actual): February 3, 2026
• Last Update Submitted That Met QC Criteria: January 30, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Keywords: cesarean section; spinal anesthesia; ultrasonography; Posterior Superior Iliac Spine; intercristal line
• Other Study ID Numbers: [2024] No. 131

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No