Primary Dysmenorrhea Treatment
A 23-year-old nulliparous woman has crampy pelvic pain starting the day before menses and lasting 2 days, severe enough to miss work each cycle. Symptoms began at menarche. Pelvic examination and transvaginal ultrasound are normal. She is sexually active and wants both reliable ongoing pain control and contraception. Which of the following is the most appropriate long-term treatment?
- A.Oral paracetamol as needed
- B.Combined hormonal contraceptive pillsCorrect
- C.Cyclical oral progestogen therapy
- D.Vaginal misoprostol each cycle
Explanation
Pain beginning with menarche, confined to the first 1 to 2 days of flow, with a normal examination and normal ultrasound, is primary dysmenorrhoea. The mechanism is excessive endometrial production of prostaglandins F2-alpha and E2 after progesterone withdrawal, causing intense myometrial contraction, raised intrauterine pressure, and uterine ischaemia. Two first-line therapies target this: non-steroidal anti-inflammatory drugs, which inhibit cyclo-oxygenase and cut prostaglandin synthesis for immediate relief, and combined hormonal contraceptives, which suppress ovulation and thin the endometrium so that far less prostaglandin is produced each cycle. For a sexually active woman who also wants contraception and sustained cycle-to-cycle control, the combined pill addresses both needs in a single agent, and continuous or extended regimens can eliminate withdrawal bleeds and their associated pain entirely. Paracetamol is a weak analgesic in this setting because it does not meaningfully reduce endometrial prostaglandin production and is inferior to non-steroidal anti-inflammatory drugs for moderate to severe cramping. Cyclical progestogens are less effective than combined preparations for primary dysmenorrhoea and are used more often in endometriosis or secondary causes. Misoprostol is a prostaglandin analogue and would worsen cramping. Failure of both first-line options after 3 to 6 months warrants laparoscopy to look for endometriosis.
Why each option
- A.
- Paracetamol gives only modest relief because it does not suppress endometrial prostaglandin production and is inferior for severe cramping.
- B.
- Correct. Combined hormonal contraceptives suppress ovulation and thin the endometrium, reducing prostaglandin-driven pain while providing contraception.
- C.
- Cyclical progestogens are less effective than combined preparations for primary dysmenorrhoea and are more often used in endometriosis.
- D.
- Misoprostol is a prostaglandin analogue that induces uterine contractions and would aggravate the pain.
Reference: UpToDate 2025, Dysmenorrhea in adult females: Treatment
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