Optimum Length of Catheter in the Epidural Space for Labor Analgesia in Non-obese Women: a Randomised Controlled Trial of 4 cm Versus 5 cm

Epidural analgesia was introduced to the world of obstetrics in 1909 by Walter Stoeckel. Over the following 100 years it has developed to become the gold-standard for delivery of intra-partum analgesia, with between 60 and 75% of North American parturients receiving an epidural during their labor. Effective labor analgesia has been shown to improve maternal and fetal outcomes. One aspect of catheter insertion that has not been fully evaluated, and with very little recent work undertaken, is the optimal length of epidural catheter to be left in the epidural space. Dislodgement or displacement of epidural catheter remains a significant cause for failure with analgesia. Novel methods of fixation may further reduce the risk of catheter migration. Another factor is the direction of travel within the epidural space, only 13% of lumbar catheters remain uncoiled after insertion of more than 4 cm into the epidural space.

Hypothesis: The investigators hypothesize that catheters inserted to 4 cm will have a lower rate of failure when compared to those inserted to 5 cm.

Objective: This study aims to evaluate the difference in quality of labor analgesia delivered by epidural catheters inserted to either 4 or 5 cm into the epidural space.

This study will be conducted as an interventional double-blinded randomised control trial to establish best practice.

Study Overview

• Status: Completed
• Conditions: Labor Pain
• Intervention / Treatment: Other: Epidural catheter

Detailed Description

Effective labor analgesia has been shown to improve maternal and fetal outcomes. It is of paramount importance to the obstetric anesthesiologist to optimize the quality of labor analgesia and identify any factors leading to ineffective epidural analgesia. One aspect of catheter insertion that has not been fully evaluated, and with very little recent work undertaken, is the optimal length of epidural catheter to be left in the epidural space.

Previous studies have advocated, for varying reasons, different lengths of catheter to be left in the space; these range from 2cm to 8cm. Longer epidural lengths in the space can be associated with foraminal escape, leading to unilateral block, and intravascular insertion, prompting additional manipulation. Shorter lengths have previously been associated with more frequent dislodgement. The directionality of the epidural catheter once in the space has been demonstrated to correlate with misdirection.

The aim of the study would be to standardize practice in how much epidural catheter is threaded into the epidural space.

• Study Type: Interventional
• Enrollment (Actual): 200
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Canada
  • Ontario
    • Toronto, Ontario, Canada, M5G1X5
      • Mount Sinai Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 50 years (Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• All women aged 18 years and above.
• In established second stage of labor.
• 3-7 cm dilation at time of insertion.
• Women with BMI < 40 kg/m2

Exclusion Criteria:

• Known contraindication to epidural insertion.
• Inability or unwillingness to provide written consent.
• Previous difficult epidural insertion.
• Previous failed epidural.
• Imminent instrumental or operative delivery.
• Dural puncture.
• Combined spinal epidural analgesia.
• High BMI > 40 kg/m2

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Triple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: 4 cm epidural catheter; The epidural catheter will be thread into the epidural space at a length of 4 cm.	Other: Epidural catheter; The epidural catheter length will vary, either 4 cm or 5 cm into the epidural space.; Other Names: epidural
Active Comparator: 5 cm epidural catheter; The epidural catheter will be thread into the epidural space at a length of 5 cm.	Other: Epidural catheter; The epidural catheter length will vary, either 4 cm or 5 cm into the epidural space.; Other Names: epidural

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Sensory block level < T10	Sensory block level to ice will be measured 1 hour after the loading dose is administered. Yes: inadequate block No: adequate block	1 hour
Block height discrepancy	Unilateral block or block height discrepancy of >3 dermatomal levels at any time prior to delivery. Yes: inadequate block No: adequate block	24 hours
Re-siting of the epidural	Re-siting of the epidural at any time during labour will indicate an inadequate block, for any of the following reasons: Inadequate analgesia; Persistent unilateral block; Persistent intravascular placement; Extensive motor block; Hypotension; High block	24 hours
Adjustment of catheter length	Adjustment of catheter length at any time during labour would also indicate an inadequate block.	24 hours
Abandonment of epidural or substitute for alternative method of analgesia after initial failure: questionnaire	The epidural analgesia will also be considered inadequate if the procedure is abandoned or another method of analgesia is used. This will be recorded by the anesthesiologist.	24 hours

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Pain score >3 at any time during labour: questionnaire	A verbal numerical rating score (VNRS) greater than 3, where 0=no pain and 10=worst pain ever.	24 hours
Number of epidural top-ups administered by the nursing team	The number of times the labour and delivery nurse has to administer a top-up of the epidural.	24 hours
Number of epidural top-ups administered by the anesthesiologist	The number of times the anesthesiologist has to administer a top-up of the epidural.	24 hours
Pain scores recorded throughout labour: questionnaire	A verbal numerical rating score (VNRS), where 0=no pain and 10=worst pain ever. A verbal numerical rating score (VNRS) greater than 3, where 0=no pain and 10=worst pain ever.	24 hours
Hourly sensory block height assessment	Hourly sensory block height assessment, using sensation to ice. This is recorded hourly as standard practice.	24 hours
Incidence of intravascular epidural placement	Any incidence of intravascular epidural placement during labour will be recorded.	24 hours
Incidence of catheter dislodgement	Any incidence of catheter dislodgement during labour will be recorded.	24 hours
Motor block using Bromage scale	Bromage scale will be recorded hourly as standard practice.; 3: Unable to move feet or knees; 2: Able to move feet only; 1: Able to just move knees; 0: Full flexion of knees and feet	24 hours
Presence of paresthesia on insertion.	Any presence of paresthesia on insertion will be recorded.	1 hour
Adequacy of conversion to surgical block if required for cesarean delivery: questionnaire	Adequacy of conversion to surgical block in cases requiring cesarean deliveries for failed labor or fetal issues. This will be recorded by the anesthesiologist.	24 hours

Collaborators and Investigators

• Sponsor: Samuel Lunenfeld Research Institute, Mount Sinai Hospital
• Investigators: Principal Investigator: Mrinalini Balki, MD, Mount Sinai Hospital

Study record dates

Study Major Dates

• Study Start (Actual): November 23, 2021
• Primary Completion (Actual): July 26, 2024
• Study Completion (Actual): July 27, 2024

Study Registration Dates

• First Submitted: June 25, 2021
• First Submitted That Met QC Criteria: June 25, 2021
• First Posted (Actual): June 30, 2021

Study Record Updates

• Last Update Posted (Actual): April 6, 2026
• Last Update Submitted That Met QC Criteria: March 31, 2026
• Last Verified: March 1, 2025

More Information

Terms related to this study

• Keywords: epidural analgesia; labor epidural; epidural catheter
• Additional Relevant MeSH Terms: Pain; Neurologic Manifestations; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Labor Pain; Therapeutics; Drug Administration Routes; Drug Therapy; Injections; Injections, Spinal; Injections, Epidural
• Other Study ID Numbers: 21-06

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