Single photobiomodulation session fails to reduce perineal trauma pain in postpartum women

OBJECTIVE: To analyze the effects of a single photobiomodulation (PBM) application on perineal pain and healing in women in the immediate postpartum period. METHODS: Randomized controlled trial, double-blind, two-center, with 60 postpartum women with perineal trauma and pain scoring 4 or more on the Numeric Rating Scale (NRS). The experimental group received red light to the lesion and infrared light around it, while the sham group received a simulation. We assessed pain with the NRS and Short-Form McGill Pain Questionnaire (SF-MPQ); tissue healing with the REEDA scale (Redness, Edema, Ecchymosis, Discharge, Approximation) at baseline, 30 min (primary outcome), and 12-36 h after intervention and satisfaction with a Likert scale 7-10 days post-intervention. We conducted bivariate analyses and an analysis of variance for repeated measures. RESULTS: The experimental and sham groups showed pain reduction with no difference between them for pain scores or healing 30 min post-intervention (mean ± SD: NRS 3.63 ± 2.57 vs 2.53 ± 2.15; P = 0.089; SF-MPQ 7.83 ± 8.32 vs 5.10 ± 6.42; P = 0.108; and REEDA 5.57 ± 3.05 vs 4.47 ± 2.42; P = 0.175). Analysis of variance revealed no significant interaction between time and group at any time point evaluated. Of the participants, 84.09% were satisfied or very satisfied with the intervention. CONCLUSIONS: Although both groups experienced a reduction in pain after the intervention, a single PBM application with these parameters was not superior to a sham treatment. Future research could explore multiple applications or different parameters. TRIAL REGISTRATION: Laser for Pain Relief in Nipple and Perineal Trauma in Postpartum; UTN code U1111-1279-3594 (https://ensaiosclinicos.gov.br/rg/RBR-2qm8jrp/1).