Pelvic pain due to endometriosis and dysmenorrhea

Abstract: Background Approximately 70% of women in reproductive age suffer from dysmenorrhea around the world but no prevalence study has been made in Sweden for 35 years. Dysmenorrhea, painful menstruation, can be a sign of endometriosis which for many is a disabling disease due to pelvic pain but also symptoms from the gastrointestinal tract, the bladder, fatigue and infertility. Treatment options for this chronic inflammatory disease as well as for dysmenorrhea are pain killers and hormonal therapy to suppress the menstrual cycle, and for endometriosis sometimes surgery. But these treatment options are not suited for everybody and are often associated with adverse effects. Preclinical trials have shown that melatonin has analgesic and anti-oxidative properties. Melatonin has shown to reduce the size of endometriotic implants in rodents. A clinical trial has showed melatonin to reduce endometriosis-associated pain more effectively than placebo. Aim To investigate the prevalence of dysmenorrhea and its impact on the life of young women in Stockholm. To investigate the analgesic effect of melatonin on severe dysmenorrhea and endometriosis-associated pain respectively, compared to placebo. A significant clinical effect was set to a reduction of 1.3 units on the numeric rating scale. Materials, methods and results Three studies were conducted during 2017-2021. Study I is a cross-sectional study. A questionnaire was sent out to all women born in the year 2000 and residing in Stockholm (n= 3998). With a response rate of 45%, the prevalence of dysmenorrhea was 89% (1580 of 1785, 95% CI 87‐90), out of which 36% (574 of 1580, 95% CI 34‐39) reported severe dysmenorrhea. High rates of fatigue (83%) and headache (82%) were observed, 14% reported monthly absenteeism and the tendency to seek medical care was low as only 7% had seen a doctor. Studies II and III are placebo-controlled, randomized trials with 40 women in each trial, 20 were allocated to placebo and 20 to melatonin. In Study II women with severe dysmenorrhea received 10 mg melatonin or placebo at bedtime for the week of menstruation during two menstrual cycles. No superior analgesic effect was seen with melatonin compared with placebo. In study III women with endometriosis-associated pain received 20 mg melatonin or placebo at bedtime for two consecutive menstrual cycles or months. No superior analgesic effect was seen with melatonin compared with placebo. Conclusions The prevalence of dysmenorrhea in Stockholm is high with substantial implications on the daily lives of young women. The low tendency to seek medical care suggests a normalization. Our chosen dose and regime could not show any analgesic effect superior to placebo, future studies are needed to investigate other doses and regimes that could be of use as adjuvant treatment of dysmenorrhea and endometriosis-associated pain.