Pudendal Nerve Block for Pain Relief During Episiotomy Repair: A Randomized Controlled Trial

Background and Rationale

Episiotomy is a surgical incision of the perineum performed during vaginal childbirth. The procedure is followed by tissue repair and may be associated with acute perineal pain and discomfort during the early postpartum period. Pain may interfere with sitting, walking, and routine postpartum activities.

Conventional local anesthetic infiltration around the episiotomy site is commonly used during repair. However, adequate anesthesia may not always be achieved. Pudendal nerve block is a regional anesthetic technique that targets the pudendal nerve, which provides sensory innervation to much of the lower vagina, vulva, perineum, and anus. It may provide anesthesia to the tissues involved in episiotomy repair.

This study will compare pudendal nerve block with conventional local perineal infiltration to evaluate their effectiveness in reducing pain during episiotomy repair and improving early postpartum comfort.

Study Design and Setting

This is a randomized controlled, parallel-group clinical trial conducted at the Department of Maternal and Child Health (MCH), Pakistan Institute of Medical Sciences (PIMS), Islamabad, Pakistan.

The planned sample size is 80 women, with 40 participants allocated to each group. Eligible women will be recruited consecutively during the study period. Following eligibility assessment and informed consent, participants will be randomly allocated in a 1:1 ratio to the intervention or control group.

The study duration is planned to be three months following institutional ethical approval, as stated in the study synopsis.

Study Population

The study population will consist of women aged 18 years or older who undergo vaginal delivery with a mediolateral episiotomy at MCH PIMS.

Inclusion Criteria

Participants must:

1. Be aged 18 years or older.
2. Have a singleton pregnancy.
3. Have a vaginal delivery at MCH PIMS.
4. Require a mediolateral episiotomy.
5. Have an uncomplicated episiotomy requiring routine repair.
6. Be able to understand the study information and provide written informed consent.

Exclusion Criteria

Women will be excluded if they have:

1. An allergy or contraindication to the proposed local anesthetic.
2. A known coagulation disorder or significant bleeding tendency.
3. Local infection at the proposed injection site.
4. An associated third- or fourth-degree perineal tear.
5. An extensive vaginal or cervical laceration requiring additional anesthesia.
6. Major postpartum hemorrhage or another major postpartum complication requiring urgent management.
7. Chronic pelvic or perineal pain, or regular use of analgesic medication before delivery.
8. An inability to understand the pain assessment scale or provide informed consent.

Study Groups and Interventions

Intervention Group: Participants will receive bilateral pudendal nerve block using the local anesthetic specified in the study protocol, in addition to routine episiotomy repair and standard postpartum analgesia. The protocol describes the proposed use of 2% lidocaine, 2 mL, for pudendal nerve block. The procedure will be performed using a standardized technique by an appropriately trained obstetrician or anesthetist.

Control Group: Participants will receive conventional local perineal infiltration anesthesia according to the standard MCH PIMS episiotomy-repair protocol.

Both groups will receive routine episiotomy repair and standard postpartum analgesia.

Outcome Measures

Primary Outcome:

The primary outcome is pain intensity during episiotomy repair, measured using a 100-mm Visual Analogue Scale (VAS), where 0 represents no pain and 100 mm represents the worst imaginable pain. Pain assessments are planned at predefined stages of repair. The specific primary assessment stage should be consistent with the finalized study protocol.

Secondary Outcomes:

1. Postpartum pain intensity measured using VAS at 1, 3, and 6 hours after delivery.
2. Requirement for rescue analgesia during the first 6 hours postpartum.
3. Time to first rescue analgesia and total rescue analgesic use during the first 6 hours.
4. Pain during sitting and walking within the first 6 hours postpartum.
5. Patient-reported comfort and satisfaction with pain management.
6. Duration of episiotomy repair.
7. Requirement for additional local anesthetic and success or failure of pudendal nerve block.
8. Frequency of complications and adverse effects associated with the procedures.

Safety Monitoring

Potential complications associated with pudendal nerve block include injection-site pain or discomfort, local hematoma, infection, excessive bleeding, local anesthetic toxicity, temporary neurological symptoms, and inadequate block. Participants will be monitored for adverse effects, and clinically significant complications will be managed according to institutional protocols.

The procedure will be performed by appropriately trained personnel using the established technique and relevant precautions for local anesthetic administration.

Data Collection and Statistical Analysis

Data will be collected using a structured data collection proforma. Baseline information will include age, gravidity and parity, gestational age, delivery-related information, indication for episiotomy, and relevant obstetric or medical history. Procedural details, pain scores, rescue analgesia, comfort, satisfaction, and adverse events will also be documented.

Data will be analyzed using SPSS version 26. Continuous variables will be summarized using means and standard deviations or medians and interquartile ranges, as appropriate. Categorical variables will be summarized using frequencies and percentages. Between-group comparisons will use appropriate statistical tests according to variable type and distribution. Repeated postoperative pain measurements will be analyzed using an appropriate repeated-measures method. A two-sided p-value of less than 0.05 will be considered statistically significant.

Blinding

Complete blinding of participants and the clinicians performing the procedures may not be feasible because the anesthetic techniques differ. Outcome assessors will be blinded to treatment allocation where feasible, and coded group identifiers will be used for statistical analysis.

Ethical Considerations

Participation will be voluntary, and informed consent will be obtained before enrollment. Participants may withdraw from the study without affecting their routine clinical care. The study will be conducted in accordance with the approved institutional protocol and applicable ethical requirements.