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NCT Number: NCT07491874

Use of Nitrous Oxide for Pain and Anxiety Management During Cervical Cerclage Removal

The goal of this clinical trial is to determine whether inhaled nitrous oxide can reduce pain and anxiety during cervical cerclage removal compared with standard care. Cervical cerclage removal is commonly performed in the outpatient setting during the third trimester of pregnancy and may be associated with discomfort and anxiety despite being a brief procedure.

The study will include pregnant women aged 18 years or older undergoing elective cervical cerclage removal at 36 weeks of gestation or later.

The main questions the study aims to answer are:

* Does inhaled nitrous oxide reduce pain during cervical cerclage removal? * Does inhaled nitrous oxide reduce anxiety during the procedure? * Does the use of nitrous oxide improve overall patient satisfaction during cerclage removal?

Researchers will compare women receiving inhaled nitrous oxide to those receiving standard care without analgesia, as routinely practiced in the participating institutions, in order to determine whether nitrous oxide improves pain control and patient experience during the procedure.

Participants will:

* Be randomly assigned to receive either inhaled nitrous oxide (50% nitrous oxide / 50% oxygen) or standard care without analgesic treatment during cervical cerclage removal. * Undergo the procedure according to routine clinical practice in the participating centers. * Complete questionnaires assessing pain and anxiety, including a visual analog scale (VAS) for pain and the State-Trait Anxiety Inventory (STAI). * Have routine clinical data recorded from their medical records, including maternal vital signs and any procedure-related side effects.

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Key information

Conditions

Preterm Delivery Abortion, Habitual Abortion, Spontaneous Cervical Cerclage Cervical Insufficiency Female Urogenital Diseases Female Urogenital Diseases and Pregnancy Complications Genital Diseases Genital Diseases, Female Obstetric Labor Complications Obstetric Labor, Premature Pregnancy Complications Premature Birth Urogenital Diseases Uterine Cervical Diseases Uterine Cervical Incompetence Uterine Diseases

Age range

18 year and older

Sex eligibility

Female

Study type

Interventional

Phase

Not applicable

Primary location

Kaplan Medical Center, Rehovot, Central District, Israel

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About this study

Cervical insufficiency is a recognized risk factor for spontaneous preterm birth, which remains a major cause of perinatal morbidity and mortality worldwide. Cervical cerclage is an established intervention used in carefully selected patients to reduce the risk of preterm birth.

While cerclage placement is typically performed under anesthesia in the operating room, cerclage removal is usually carried out in the outpatient setting during the late third trimester of pregnancy. Despite being a brief procedure, many patients experience pain, discomfort, and anxiety during cerclage removal. Evidence regarding optimal pain management strategies for this procedure remains limited, and most patients currently undergo cerclage removal without analgesia.

Nitrous oxide (N₂O) is an inhaled gas with well-established analgesic and anxiolytic properties. It has a rapid onset and offset of action and a favorable safety profile. Nitrous oxide is widely used in obstetrics, particularly for labor analgesia, and has also been used for pain management during minor medical procedures. However, its use specifically for cervical cerclage removal has not been well studied.

This study is a multicenter randomized controlled trial designed to evaluate whether inhaled nitrous oxide reduces pain and anxiety during elective cervical cerclage removal. Participants will be randomly assigned in a 1:1 ratio to receive either inhaled nitrous oxide (50% nitrous oxide / 50% oxygen) during the procedure or standard care without analgesic treatment, as routinely practiced in the participating institutions. Randomization will be stratified by site and implemented using sequentially numbered sealed envelopes opened immediately prior to the procedure.

All procedures will be performed according to routine clinical practice in the participating centers. Maternal and procedural data will be collected from medical records, including procedure duration, maternal vital signs, and any reported side effects such as nausea, dizziness, or headache. Pain intensity will be assessed using a 0-100 mm visual analog scale (VAS), and anxiety levels will be evaluated using the State-Trait Anxiety Inventory (STAI). Additional outcomes will include maternal heart rate during the procedure and patient satisfaction with the procedure.

This trial aims to determine whether inhaled nitrous oxide can effectively reduce pain and anxiety during cervical cerclage removal. The findings of this study may provide evidence to support improved pain management strategies for this procedure and may contribute to enhancing patient experience during cerclage removal.

Who can participate

Healthy volunteers accepted: No

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

Inclusion criteria

  • Age ≥18 years
  • Women at ≥34 weeks of gestation
  • Singleton or twin pregnancy
  • Ability to understand, sign informed consent, and complete questionnaires

Exclusion criteria

  • Triplet or higher-order pregnancy
  • Contraindications to nitrous oxide use
  • Fetal monitoring category 2 or higher
  • Maternal body temperature >38°C
  • Significant vaginal bleeding
  • Severe preeclampsia
  • Cerclage removal under general anesthesia
  • Language or cognitive barrier
  • Baseline pain >3 on VAS scale, prior to the procedure

Treatment and study plan

Inhaled nitrous oxide

Drug

Inhaled nitrous oxide (50% nitrous oxide / 50% oxygen) administered via a demand-valve mask during cervical cerclage removal. The system includes a one-way valve and is self-administered by the patient, who holds the mask and inhales as needed. The device is identical to the equipment routinely used for labor analgesia in the participating institutions and is operated and monitored by trained midwives experienced in nitrous oxide administration.

Nitrous oxide inhalation begins following instruction from the performing physician. The procedure starts approximately three minutes after inhalation begins, once adequate analgesia and anxiolysis are achieved. Continuous pulse oximetry monitoring is performed during administration. After completion of the procedure, nitrous oxide is discontinued and the patient breathes room air.

Other names: N2O

Primary outcomes

  1. Pain intensity during cervical cerclage removal

    Time frame: 3-5 minutes following completion of the procedure

    Pain intensity will be assessed using a 0-100 mm visual analog scale (VAS). Participants will rate the level of pain experienced during the procedure 3-5 minutes after completion of the cerclage removal.

Secondary outcomes

  1. Difference between expected pain and experienced pain

    Time frame: Baseline (prior to procedure) and 3-5 minutes following completion of the procedure

    Expected and experienced pain will be assessed using a 0-100 mm Visual Analog Scale (VAS), where higher scores indicate greater pain intensity. The difference between expected and experienced pain scores will be calculated.

  2. Procedure duration

    Time frame: During procedure

    Total duration of the cerclage removal procedure, measured in minutes from the beginning of the procedure to completion.

  3. Change in maternal heart rate during procedure

    Time frame: Baseline measurement prior to the procedure and continuous monitoring during the procedure

    Difference (delta) between baseline maternal heart rate and the maximal heart rate recorded during the procedure

  4. Change in anxiety level (STAI)

    Time frame: Baseline (before procedure) and 3-5 minutes after completion of the procedure

    Anxiety levels will be assessed using the State-Trait Anxiety Inventory (STAI). The STAI score ranges from 20 to 80, with higher scores indicating higher levels of anxiety. Participants will complete the questionnaire before the procedure and again after cerclage removal. The change in STAI score will be analyzed.

  5. Patient satisfaction

    Time frame: 3-5 minutes after completion of the procedure

    Patient satisfaction will be assessed using a 5-point Likert scale, where 1 indicates very low satisfaction and 5 indicates very high satisfaction. The questionnaire will be completed after cerclage removal.

  6. Adverse events

    Time frame: During procedure

    Occurrence of adverse events including nausea, dizziness, headache, or dyspnea reported during or immediately after the procedure

  7. Conversion to neuraxial or general anesthesia

    Time frame: During the procedure

    Need to convert from the assigned study condition (nitrous oxide or no analgesia) to epidural, spinal, or general anesthesia due to inability to complete the procedure

  8. Physician-rated procedural difficulty

    Time frame: 3-5 minutes following completion of the procedure

    The performing physician will provide a subjective assessment of the technical difficulty of cervical cerclage removal. Procedural difficulty will be assessed using a 5-point Likert scale, where 1 indicates very easy and 5 indicates very difficult.

Study contacts

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

Gil Friedman

CONTACT

[email protected]

+972584744356

Sponsors and collaborators

Lead sponsor

Kaplan Medical Center

Other

Collaborators

  • Clalit Health Services
  • Meir Medical Center
  • Rabin Medical Center
  • Wolfson Medical Center

Registry information

Official study title

Use of Nitrous Oxide for Pain and Anxiety Management During Cervical Cerclage Removal- A Multicenter Randomized Controlled Study

Important dates

Study start
2026
Primary completion
2028
Study completion
2028
First posted
Mar 25, 2026
Registry last updated
Apr 8, 2026

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

View the official ClinicalTrials.gov record (opens in a new tab)

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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