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

Context, rationale and hypothesis: Majority of pregnant women undergo vaginal deliveryand although episiotomy is not recommended to be performed routinely, obstetric practicesvary worldwide. At a maternity hospital in Vietnam, the reported episiotomy rate was82.6% in primiparous and 22.8% in multiparous women. Depending on the degree of tissuetrauma and other factors, the reported incidence of persistent post‐episiotomy pain canrange from 12% to 55% on the 2nd to 5th month. Dyspareunia is a complaint of persistentor recurrent pain or discomfort associated with attempted or completed vaginalpenetration. Postpartum dyspareunia is common, with frequencies varying between 20% to40% 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 monthpostpartum among women who had episiotomy. As such perineal trauma remains commonfollowing vaginal delivery and is associated with a high incidence of acute postpartumpain, which may progress to chronic pain and dyspareunia. Chronic post‐surgical pain isstrongly linked to inadequate early pain control, supporting the rationale for aggressivemultimodal analgesia. The pudendal nerve plays a central role in perineal nociception.While single‐shot pudendal nerve block has demonstrated efficacy in reducing acutepost‐episiotomy pain, its role in preventing chronic pain and dyspareunia remainsunclear. Repeated pudendal nerve block combined with physiotherapy may reduce centralsensitization and improve long‐term outcomes.Originality and innovative aspects: Thepudendal nerve block has been consistently demonstrated to be effective in the managementof acute perineal pain, as supported by multiple randomized controlled trials. Its rolein immediate postpartum analgesia is therefore well established. However, a substantialgap persists in the literature regarding its potential long‐term benefits. Specifically,there is a near absence of studies evaluating the prevention of chronic post‐episiotomypain, despite the significant burden associated with this condition. Furthermore, dataaddressing postpartum dyspareunia remain extremely limited, leaving an importantdimension of maternal health insufficiently explored. Pelvic floor physiotherapy iswidely recommended as part of postpartum care. Nevertheless, it is rarely investigated incombination with regional anesthesia techniques in clinical trials, representing a missedopportunity to assess potential synergistic effects on both pain modulation andfunctional recovery. Additionally, repeated nerve block strategies have shown promise inthe management of neuropathic pain in other clinical contexts. Yet, this approach has notbeen evaluated in obstetric populations, particularly in the postpartum setting. Takentogether, the proposed study addresses critical unmet needs by exploring a novel,multimodal strategy that integrates repeated pudendal nerve blocks with pelvic floorrehabilitation. This approach is highly original and holds significant scientificrelevance, with the potential to redefine preventive strategies for chronic postpartumperineal pain and associated sexual dysfunction.Main and secondary objectives:OutcomesPrimary Outcome: Composite outcome of pain intensity VAS > 3 or dyspareuniaassessed 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 andmonth 3 Level of dyspareunia assessed using the Female Sexual Function Index at: Week 8and month 3.Obstetric of recovery ‐10 (ObsQoR‐10) ) at day of discharge, day 10. DouleurNeuropathique en 4 questions (DN4) Score at Day 10, week 8 and 3 months .Identification of risk factors for chronic pain and dyspareunia Pudendal nerve blockfailure (defined as <50% pain relief at 30 minutes) Adverse events incidence : Localanesthetic systemic toxicity, Hematoma, Infection or Rectal perforation Methods Thisstudy is a prospective, single‐center, open‐label, parallel‐group randomized controlledtrial with a 1:1 allocation ratio. The trial is designed in accordance with the consortconsolidated 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: OralParacetamol 500 mg every 6 hours; Oral Celecoxib 200 mg every 12 hours; Oral Nefopam asneeded for pain >3/10 and a Standardized physiotherapy program: Breathing exercises ;Pelvic floor exercises and a Perineal massage Intervention Group (Repeated Pudendal NerveBlock + Standard Management): Participants will receive standard management plus: Arepeat pudendal nerve block prior to hospital discharge; The Block Technique: Dualguidance (ultrasound and nerve stimulator); Transperineal approach; Injection of 8 mL0.5% Ropivacaine with 4 mg dexamethasone; Ipsilateral location.Sample Size: Assuming a reduction in chronic pain incidence from 40% to 20%, with atwo‐sided alpha of 0.05 and 80% power, 94 participants (47 per group) are required. Toaccount for a 10% dropout rate, a total of 104 participants will be enrolled. Analysis ofthe Population: Intention‐to‐treat (ITT) (primary analysis) and Per‐protocol (sensitivityanalysis) Descriptive Statistics: Continuous variables: mean ± SD or median (IQR) andCategorical variables: n (%) Comparison between groups using chi‐square test or Fisher'sexact test and Effect measures: Risk Ratio (RR) with 95% confidence interval and Absoluterisk difference (B) Continuous composite score (secondary analysis): Standardization(z‐scores) of BPI and FSFI pain domain scores; Aggregation into a single continuouscomposite score (e.g., mean of standardized values) Multiplicity and Hierarchy : Thebinary composite endpoint is the primary endpoint; Continuous composite and individualcomponents are secondary/exploratory; Adjustment for multiple testing (e.g., Holm orBonferroni) will be applied for secondary analyses Pain Scores longitudinal:Mixed‐effects linear model; Fixed effects: group, time, group × time interactionDyspareunia (binary outcome) : Chi‐square test or Fisher's exact test; Relative risk (RR)with 95% CI Secondary Analyses : Logistic regression (Identify predictors of chronicpain/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 randomizationlist will be used.Allocation will be implemented using sequentially numbered, sealed,opaque envelopes.Implementation: Participants will be enrolled by investigators andassigned to groups according to the randomization sequence.Blinding: Due to the nature ofthe intervention, participants and treating clinicians cannot be blinded. However,outcome assessors and data analysts will be blinded to group allocation.Data CollectionMethods: Pain and functional outcomes will be assessed at predefined time points usingvalidated questionnaires: VAS ruler and Female Sexual Function Index. Data will becollected during follow‐up visits or via structured interviews.