Repeated Pudendal Nerve Block and Physiotherapy for Prevention of Chronic Post-Episiotomy Pain

Context, rationale and hypothesis: Majority of pregnant women undergo vaginal delivery and although episiotomy is not recommended to be performed routinely, obstetric practices vary worldwide. At a maternity hospital in Vietnam, the reported episiotomy rate was 82.6% in primiparous and 22.8% in multiparous women. Depending on the degree of tissue trauma and other factors, the reported incidence of persistent post-episiotomy pain can range from 12% to 55% on the 2nd to 5th month. Dyspareunia is a complaint of persistent or recurrent pain or discomfort associated with attempted or completed vaginal penetration. Postpartum dyspareunia is common, with frequencies varying between 20% to 40% at six months and 13% to 60% in the first year. A study in Vietnam revealed 40.7% prevalence of sexual dysfunction (dyspareunia and lack of desire) on the 3rd month postpartum among women who had episiotomy. As such perineal trauma remains common following vaginal delivery and is associated with a high incidence of acute postpartum pain, which may progress to chronic pain and dyspareunia. Chronic post-surgical pain is strongly linked to inadequate early pain control, supporting the rationale for aggressive multimodal analgesia. The pudendal nerve plays a central role in perineal nociception. While single-shot pudendal nerve block has demonstrated efficacy in reducing acute post-episiotomy pain, its role in preventing chronic pain and dyspareunia remains unclear. Repeated pudendal nerve block combined with physiotherapy may reduce central sensitization and improve long-term outcomes.Originality and innovative aspects: The pudendal nerve block has been consistently demonstrated to be effective in the management of acute perineal pain, as supported by multiple randomized controlled trials. Its role in immediate postpartum analgesia is therefore well established. However, a substantial gap persists in the literature regarding its potential long-term benefits. Specifically, there is a near absence of studies evaluating the prevention of chronic post-episiotomy pain, despite the significant burden associated with this condition. Furthermore, data addressing postpartum dyspareunia remain extremely limited, leaving an important dimension of maternal health insufficiently explored. Pelvic floor physiotherapy is widely recommended as part of postpartum care. Nevertheless, it is rarely investigated in combination with regional anesthesia techniques in clinical trials, representing a missed opportunity to assess potential synergistic effects on both pain modulation and functional recovery. Additionally, repeated nerve block strategies have shown promise in the management of neuropathic pain in other clinical contexts. Yet, this approach has not been evaluated in obstetric populations, particularly in the postpartum setting. Taken together, the proposed study addresses critical unmet needs by exploring a novel, multimodal strategy that integrates repeated pudendal nerve blocks with pelvic floor rehabilitation. This approach is highly original and holds significant scientific relevance, with the potential to redefine preventive strategies for chronic postpartum perineal pain and associated sexual dysfunction.Main and secondary objectives: OutcomesPrimary Outcome: Composite outcome of pain intensity VAS > 3 or dyspareunia assessed using the Female Sexual Function Index \< 26,55 at week 8 Secondary Outcomes. Pain intensity assessed using the Visual analogue scale (VAS) ruler Day 10, week 8 and month 3 Level of dyspareunia assessed using the Female Sexual Function Index at: Week 8 and month 3.

Obstetric of recovery -10 (ObsQoR-10) ) at day of discharge, day 10. Douleur Neuropathique en 4 questions (DN4) Score at Day 10, week 8 and 3 months .

Identification of risk factors for chronic pain and dyspareunia Pudendal nerve block failure (defined as \<50% pain relief at 30 minutes) Adverse events incidence : Local anesthetic systemic toxicity, Hematoma, Infection or Rectal perforation Methods This study is a prospective, single-center, open-label, parallel-group randomized controlled trial with a 1:1 allocation ratio. The trial is designed in accordance with the consort consolidated standards of reporting trials 2010 Statement.

Setting The study will be conducted at VinMec International Hospital, Times City, Hanoi, Vietnam.InterventionsControl Group (Standard Management): Participants will receive: Oral Paracetamol 500 mg every 6 hours; Oral Celecoxib 200 mg every 12 hours; Oral Nefopam as needed for pain >3/10 and a Standardized physiotherapy program: Breathing exercises ; Pelvic floor exercises and a Perineal massage Intervention Group (Repeated Pudendal Nerve Block + Standard Management): Participants will receive standard management plus: A repeat pudendal nerve block prior to hospital discharge; The Block Technique: Dual guidance (ultrasound and nerve stimulator); Transperineal approach; Injection of 8 mL 0.5% Ropivacaine with 4 mg dexamethasone; Ipsilateral location.

Sample Size: Assuming a reduction in chronic pain incidence from 40% to 20%, with a two-sided alpha of 0.05 and 80% power, 94 participants (47 per group) are required. To account for a 10% dropout rate, a total of 104 participants will be enrolled. Analysis of the Population: Intention-to-treat (ITT) (primary analysis) and Per-protocol (sensitivity analysis) Descriptive Statistics: Continuous variables: mean ± SD or median (IQR) and Categorical variables: n (%) Comparison between groups using chi-square test or Fisher's exact test and Effect measures: Risk Ratio (RR) with 95% confidence interval and Absolute risk difference (B) Continuous composite score (secondary analysis): Standardization (z-scores) of BPI and FSFI pain domain scores; Aggregation into a single continuous composite score (e.g., mean of standardized values) Multiplicity and Hierarchy : The binary composite endpoint is the primary endpoint; Continuous composite and individual components are secondary/exploratory; Adjustment for multiple testing (e.g., Holm or Bonferroni) will be applied for secondary analyses Pain Scores longitudinal: Mixed-effects linear model; Fixed effects: group, time, group × time interaction Dyspareunia (binary outcome) : Chi-square test or Fisher's exact test; Relative risk (RR) with 95% CI Secondary Analyses : Logistic regression (Identify predictors of chronic pain/dyspareunia); Kaplan-Meier (optional): Time to pain resolution Handling Missing Data : Multiple imputation if >5% missing; Sensitivity analysis Significance Threshold : p \< 0.05 (two-sided) RandomizationSequence Generation: A computer-generated randomization list will be used.Allocation will be implemented using sequentially numbered, sealed, opaque envelopes.Implementation: Participants will be enrolled by investigators and assigned to groups according to the randomization sequence.Blinding: Due to the nature of the intervention, participants and treating clinicians cannot be blinded. However, outcome assessors and data analysts will be blinded to group allocation.Data Collection Methods: Pain and functional outcomes will be assessed at predefined time points using validated questionnaires: VAS ruler and Female Sexual Function Index. Data will be collected during follow-up visits or via structured interviews.