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NCT Number: NCT07396961

Consistency of ASIS Line vs. Tuffier's Line for Lumbar Level Identification

Tuffier's line is commonly used as a landmark for estimating lumbar vertebral levels during spinal anesthesia. However, its accuracy can vary depending on factors such as age, sex, BMI, and posture. This study evaluates the consistency of an alternative landmark, the "ASIS line" (a line connecting both Anterior Superior Iliac Spines), for identifying lumbar levels in the lateral decubitus position. Researchers will mark both the ASIS line and Tuffier's line on participants and use ultrasound to verify the exact vertebral level where each line crosses the spine. The goal is to determine if the ASIS line provides a more consistent and reliable estimation of lumbar levels compared to Tuffier's line.

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Key information

Conditions

Spinal Anesthesia Evaluation Lumbar Vertebrae

Age range

18 year–85 year

Sex eligibility

All sexes

Study type

Observational

Primary location

St. Vincent's Hospital, Suwon, North Carolina, South Korea

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Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Adults aged 18 to 85 years
  • Patients scheduled for spinal anesthesia or lumbar ultrasound
  • Participants who voluntarily agreed to participate and provided written informed consent

Exclusion criteria

  • History of spinal surgery or spinal deformity
  • Infection or wounds at the puncture site
  • Inability to maintain the lateral decubitus position
  • Congenital lumbosacral transitional vertebrae (e.g., sacralized L5 or lumbarized S1)
  • Any other condition deemed unsuitable for the study by the investigator

Treatment and study plan

Lumbar Ultrasound & Palpation

Diagnostic Test

Identification of vertebral levels using Tuffier's line (palpation) and ASIS line, followed by ultrasound verification.

Primary outcomes

  1. Consistency of Vertebral Level Identification (Standard Deviation)

    Time frame: Day 1 (Immediately during the ultrasound examination)

    The specific vertebral level where the ASIS line and Tuffier's line intersect the spine will be identified using ultrasound. The lumbar spine (from L2 upper to S1 upper) is divided into segments (e.g., L2=2, L3=3, L4=4, L5=5, S1=6). The consistency of each method is evaluated by calculating and comparing the standard deviation (SD) of the identified vertebral levels.

Secondary outcomes

  1. Difference in Mean Intersection Level

    Time frame: Day 1

    Comparison of the mean vertebral levels identified by the ASIS line versus Tuffier's line to determine if there is a significant difference in the average level indicated.

  2. Rate of Identification within L4-L5 Interspace

    Time frame: Day 1

    The percentage of cases where the identified line falls within the target L4-L5 interspace (or within ±1 interspace range).

Study contacts

Contact information is provided by the study sponsor or research team.

Sung Hyun Lee, MD, PhD

CONTACT

[email protected]

+82-2-2001-1666

Sponsors and collaborators

Lead sponsor

Kangbuk Samsung Hospital

Other

Registry information

Official study title

Evaluation of the Consistency of the ASIS Line for Lumbar Level Identification in the Lateral Decubitus Position: Comparison With the Tuffier's Line

Important dates

Study start
2026
Primary completion
2027
Study completion
2028
First posted
Feb 9, 2026
Registry last updated
Feb 9, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

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This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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