Treatment of Postpartum Myofascial Perineal Pain and Dyspareunia Through Local Anaesthetic Infiltrations Compared to Anaesthetic and Corticosteroids: A Randomised Double-Blind Clinical Trial

<b>Background/Objectives</b>: The objective is to assess if transvaginal infiltration with anaesthetic only is non-inferior compared to anaesthetic plus corticosteroid for the treatment of myofascial pelvic pain. <b>Methods</b>: A randomised, double-blind, parallel-group (1:1) clinical trial was set at the Department of Obstetrics and Gynaecology, Hospital Universitario "Príncipe de Asturias" from December 2017 to June 2023. Women presenting myofascial perineal pain ≥ 4 on the visual analogue scale (VAS) 2 months after delivery, with instrumental delivery or prolonged second stage (>3 h) or foetal weight > 4000 g, were randomised into two groups to receive levobupivacaine 5 mg/mL or levobupivacaine 5 mg/mL plus betamethasone 3 mg/mL. For each trigger point detected, a transvaginal infiltration was performed using the corresponding treatment. The patients were followed up to 6 months. The primary endpoint was a change in the VAS score from baseline at 6 months. <b>Results</b>: A total of 114 women were enrolled, with 57 randomly assigned to each group. The median (IQR) VAS 2 weeks after infiltration decreased by a similar magnitude: median (IQR) 2 (1-3) in the levobupivacaine group and 2 (1-4) in the levobupivacaine + betamethasone group (<i>p</i>-value = 0.33). The same trend was observed at 6 months: median (IQR) 1 (1-4) in the levobupivacaine group and 1 (1-2) in the levobupivacaine + betamethasone group (<i>p</i>-value = 0.85). <b>Conclusions</b>: This study provides evidence that the use of anaesthetic-only infiltration is non-inferior compared to anaesthetic plus corticosteroid for the treatment of myofascial perineal pain.