Efficacy of Thread - Embedding Acupuncture for the Treatment of Primary Dysmenorrhea

This randomized, assessor-blinded, controlled clinical trial evaluated thread-embedding acupuncture (TEA) as an adjunct to standard treatment for primary dysmenorrhea in women aged 18 to 29 years. The study was conducted at the University Medical Center Ho Chi Minh City, Branch 3, Vietnam, from September 2024 to April 2025.

Participants were randomly assigned in an approximately 1:1 ratio to either the TEA group or the control group. Both groups received the same standard treatment. The TEA group additionally received thread-embedding acupuncture.

Standard treatment included heat therapy and rescue ibuprofen. A warm pack at approximately 40 to 45°C was applied to the lower abdomen for 15 to 20 minutes when menstrual pain reached a visual analogue scale (VAS) score of 4 or higher. Heat therapy could be repeated every 2 to 3 hours as needed. Ibuprofen 400 mg was used as rescue medicine when menstrual pain reached a VAS score of 7 or higher and was continued until pain or discomfort improved to a VAS score below 4, for a maximum of 3 days during each menstrual cycle.

Thread-embedding acupuncture was performed by a licensed physician trained and certified in the technique. Sterile, single-use, preloaded polydioxanone (PDO) absorbable threads were used. Each device consisted of a 30-gauge needle with a 25-mm shaft and a 30-mm PDO thread.

Participants assigned to the TEA group received two courses of thread-embedding acupuncture. Each course was performed 3 to 7 days before the expected onset of menstruation during two consecutive menstrual cycles.

The core acupuncture points used for all participants in the TEA group were: Sanyinjiao (SP6), Guanyuan (CV4), Qihai (CV6), Xuehai (SP10), Zigong (EX-CA1) Additional points were selected according to the participant's Traditional Chinese Medicine (TCM) syndrome pattern.

For participants classified as having an Excess Cold pattern, the additional points were: Pishu (BL20), Shenshu (BL23), Ganshu (BL18), Neiguan (PC6), Taichong (LR3) For participants classified as having Qi stagnation and Blood stasis, the additional points were: Tianshu (ST25), Zhongdu (LR6) Acupuncture point locations were determined according to World Health Organization standards.

Participants were followed over three consecutive menstrual cycles. Assessments were performed at four time points:

• T0: baseline, before treatment
• T1: first intervention menstrual cycle
• T2: second intervention menstrual cycle
• T3: first menstrual cycle after completion of the TEA intervention The primary outcome was menstrual pain intensity measured using a 10-cm visual analogue scale. The scale ranged from 0, meaning no pain, to 10, meaning the worst pain imaginable. Participants marked the point that best represented their pain intensity. The highest VAS score during the most recent menstrual cycle before enrollment was recorded as the baseline value. Follow-up VAS scores were recorded during T1, T2, and T3.

Secondary outcomes included TCM syndrome scores and rescue ibuprofen use. TCM syndrome scores were assessed using the syndrome-specific scoring instrument described by Le Ngo Minh Nhu and Trinh Thi Dieu Thuong. Participants were evaluated for either the Excess Cold pattern or the Qi stagnation and Blood stasis pattern. Syndrome scores were recorded at T0, T1, T2, and T3.

Rescue medication use was measured as the total number of 400-mg ibuprofen tablets taken during each menstrual cycle. Participants contacted the outcome assessor when their pain reached a VAS score of 7 or higher. The assessor then recorded the amount of ibuprofen used during that cycle.

Safety was monitored throughout the study. Adverse events occurring in the TEA group were actively recorded after treatment. Events monitored included pain at the insertion site, dizziness, local discomfort, local skin irritation such as itching or redness, local inflammation, bleeding, chondritis, and nausea.

The study also monitored for serious adverse events. A serious adverse event was defined as an event resulting in death, a life-threatening condition, initial or prolonged hospitalization, disability or permanent damage, or the need for medical intervention to prevent permanent impairment.

Adverse events occurring during ibuprofen use were also monitored and recorded as present or absent.

Outcome assessments were performed by trained assessors who were not informed of participants' treatment allocation. Assessments were conducted at baseline, during both intervention cycles, and during the first menstrual cycle after the intervention period.