---
title: Effect of Crossed Legged Position on Ultrasound Measured Posterior Longitudinal Ligament Length in Parturients.
nct_id: NCT04277988
overall_status: COMPLETED
sponsor: "London Health Sciences Centre Research Institute OR Lawson Research Institute of St. Joseph's"
study_type: OBSERVATIONAL
primary_condition: Pregnancy
canonical_url: "https://parkinsonspathways.com/agent/trials/NCT04277988.md"
clinicaltrials_gov: "https://clinicaltrials.gov/study/NCT04277988"
ct_last_update_post_date: 2020-02-20
last_seen_at: "2026-05-12T06:14:59.585Z"
source: ClinicalTrials.gov (mirrored, no enrichment)
---
# Effect of Crossed Legged Position on Ultrasound Measured Posterior Longitudinal Ligament Length in Parturients.

**Official Title:** A Comparison of the Ultrasound Measured Posterior Longitudinal Ligament Length in Parturients in the Standard Sitting and Crossed Leg Positions: an Observational Study

**NCT ID:** [NCT04277988](https://clinicaltrials.gov/study/NCT04277988)

## Key Facts

- **Status:** COMPLETED
- **Study Type:** OBSERVATIONAL
- **Target Enrollment:** 30
- **Lead Sponsor:** London Health Sciences Centre Research Institute OR Lawson Research Institute of St. Joseph's
- **Conditions:** Pregnancy
- **Start Date:** 2016-03
- **Completion Date:** 2016-12
- **CT.gov Last Update:** 2020-02-20

## Brief Summary

To investigate if sitting in flexed cross legged position for neuraxial techniques in term pregnant patients widens the size of the ultrasound acoustic window as measured by the visualized posterior longitudinal ligament length, during lumbar spine ultrasonography using longitudinal paramedian view, in comparison to the standard sitting flexed position.

## Detailed Description

This is a prospective observational study involving a total of 30 healthy term gestation pregnant patients with singleton fetuses.Patients will be randomly allocated to sit crossed leg or in standard position first. Using ultrasonography, the acoustic window for lumbar spinal anesthesia at L3-4 will be evaluated in both traditional sitting and crossed leg positions. Ultrasonography will be performed sequentially to measure the best visualized length of posterior longitudinal ligament,ligamentum flavum and interlaminar distance in the paramedian view.The scanned image will be saved to be remeasured by a third observer. Patients will be asked to score their comfort level while sitting in both positions.

## Eligibility

- **Minimum age:** 18 Years
- **Maximum age:** 40 Years
- **Sex:** FEMALE
- **Healthy Volunteers:** Yes

```
Inclusion Criteria:

Term gestation Singleton pregnancy 18 years or older Patients having elective cesarean delivery or induction of labor or in early labor

Exclusion Criteria:

* Allergy to ultrasound jelly
* Spinal Deformities/Previous spinal surgery
* No contraindication to neuraxial placement
* Any fetal concerns
* Morbid obesity
* Language barrier
```

## Arms

- **Crossed leg position** — Patients in this group will be randomly allocated to sit in crossed leg position first.Ultrasonography will be performed in this position to measure the best visualized length of posterior longitudinal ligament, ligamentum flavum and interlaminar distance at L3-4 lumbar level as by Operator 1 . These measurements will be recorded by Operator 2 using intrinsic caliper software.Operator 1 will not be told the measurements.
- **Standard Sitting position** — Patients in this group will be randomly allocated to sit in standard position first.Ultrasonography will be performed in this position to measure the best visualized length of posterior longitudinal ligament, ligamentum flavum and interlaminar distance at L3-4 lumbar level as by Operator 1 . These measurements will be recorded by Operator 2 using intrinsic caliper software.Operator 1 will not be told the measurements.

## Interventions

- **Ultrasonography** (DEVICE) — Length of Posterior Longitudianl Ligament, Ligamentum Flavum and Interlaminar distance visible in paramedian longitudinal view during lumbar spine ultrasonography in cross legged position will be compared to standard sitting position.

## Primary Outcomes

- **PLL length** _(time frame: Up to Five minutes)_ — Length of the Paravertebral Longitudinal Ligament, as measured by the intrinsic ultrasound caliber tool in mm.

## Secondary Outcomes

- **LF length** _(time frame: Up to Five minutes)_
- **ILD length** _(time frame: Up to Five minutes)_
- **Patient Comfort** _(time frame: Up to 5 minutes)_

## Recent Field Changes (last 30 days)

- `status.overallStatus` — added _(2026-05-12)_
- `status.primaryCompletionDate` — added _(2026-05-12)_
- `status.completionDate` — added _(2026-05-12)_
- `status.lastUpdatePostDate` — added _(2026-05-12)_
- `design.enrollmentCount` — added _(2026-05-12)_
- `eligibility.criteria` — added _(2026-05-12)_
- `eligibility.minAge` — added _(2026-05-12)_
- `eligibility.maxAge` — added _(2026-05-12)_
- `eligibility.sex` — added _(2026-05-12)_
- `outcomes.primary` — added _(2026-05-12)_
- `outcomes.secondary` — added _(2026-05-12)_
- `armsInterventions.arms` — added _(2026-05-12)_
- `armsInterventions.interventions` — added _(2026-05-12)_
- `sponsor.lead` — added _(2026-05-12)_
- `results.hasResults` — added _(2026-05-12)_

---

*Canonical: https://parkinsonspathways.com/agent/trials/NCT04277988.md*  
*Source data (authoritative): https://clinicaltrials.gov/study/NCT04277988*  
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