CASE Endometriosis pain increases despite hormonal treatment
A 25-year-old woman (G0) with severe dysmenorrhea had a laparoscopy showing endometriosis in the cul-de-sac and a peritoneal window near the left uterosacral ligament. Biopsy of a cul-de-sac lesion showed endometriosis on histopathology. The patient was treated with a continuous low-dose estrogen-progestin contraceptive. Initially, the treatment helped relieve her pain symptoms. Over the next year, while on that treatment, her pain gradually increased in severity until it was disabling. At an office visit, the primary clinician renewed the estrogen-progestin contraceptive for another year, even though it was not relieving the patient’s pain. The patient sought a second opinion.
We are the experts in the management of pelvic pain caused by endometriosis
Women’s health clinicians are the specialists best trained to care for patients with severe pain caused by endometriosis. Low-dose continuous estrogen-progestin contraceptives are commonly prescribed as a first-line hormonal treatment for pain caused by endometriosis. My observation is that estrogen-progestincontraceptives are often effective when initially prescribed, but with continued use over years, pain often recurs. Estrogen is known to stimulate endometriosis disease activity. Progestins at high doses suppress endometriosis disease activity. However, endometriosis implants often manifest decreased responsiveness to progestins, permitting the estrogen in the combination contraceptive to exert its disease-stimulating effect.1,2 I frequently see women with pelvic pain caused by endometriosis, who initially had a significant decrease in pain with continuous estrogen-progestin contraceptive treatment but who develop increasing pain with continued use of the medication. In this clinical situation, it is useful to consider stopping the estrogen-progestin therapy and to prescribe a hormone with a different mechanism of action (TABLE).
Progestin-only medications are often effective in the treatment of pain caused by endometriosis. High-dose progestin-only medications suppress pituitary secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), thereby suppressing ovarian synthesis of estrogen, resulting in low circulating levels of estrogen. This removes the estrogen stimulus that exacerbates endometriosis disease activity. High-dose progestins also directly suppress cellular activity in endometriosis implants. High-dose progestins often overcome the relative resistance of endometriosis lesions to progestin suppression of disease activity. Hence, high-dose progestin-only medications have two mechanisms of action: suppression of estrogen synthesis through pituitary suppression of LH and FSH, and direct inhibition of cellular activity in the endometriosis lesions. High-dose progestin-only treatments include:
- oral norethindrone acetate 5 mg daily
- oral medroxyprogesterone acetate (MPA) 20 to 40 mg daily
- subcutaneous, or depot MPA
- levonorgestrel-releasing intrauterine device (LNG-IUD).
In my practice, I frequently use oral norethindrone acetate 5 mg daily to treat pelvic pain caused by endometriosis. In one randomized trial, 90 women with pelvic pain and rectovaginal endometriosis were randomly assigned to treatment with norethindrone acetate 2.5 mg daily or an estrogen-progestin contraceptive. After 12 months of treatment, satisfaction with treatment was reported by 73% and 62% of the women in the norethindrone acetate and estrogen-progestin groups, respectively.3 The most common adverse effects reported by women taking norethindrone acetate were weight gain (27%) and decreased libido (9%).
Oral MPA at doses of 30 mg to 100 mg daily has been reported to be effective for the treatment of pelvic pain caused by endometriosis. MPA treatment can induce atrophy and pseudodecidualization in endometrium and endometriosis implants. In my practice I typically prescribe doses in the range of 20 mg to 40 mg daily. With oral MPA treatment, continued uterine bleeding may occur in up to 30% of women, somewhat limiting its efficacy.4–7
Subcutaneous and depot MPA have been reported to be effective in the treatment of pelvic pain caused by endometriosis.4,8 In some resource-limited countries, depot MPA may be the most available progestin for the treatment of pelvic pain caused by endometriosis.
The LNG-IUD, inserted after surgery for endometriosis, has been reported to result in decreased pelvic pain in studies with a modest number of participants.9–11