Dysmenorrhoea

Dysmenorrhoea is painful menstruation, usually cramping lower abdominal pain beginning with or just before bleeding and lasting 1 to 3 days. Primary dysmenorrhoea has no pelvic pathology and starts within 1 to 2 years of menarche once ovulatory cycles begin. Secondary dysmenorrhoea results from pelvic disease, usually starts later in life or changes in character, and needs investigation.

The main clinical point is to treat primary dysmenorrhoea with prostaglandin inhibition and hormonal suppression, and to identify secondary causes (endometriosis, adenomyosis, obstructive anomalies) when pain is severe, progressive or unresponsive.

Clinical relevance. It is the commonest gynaecological symptom in adolescents and a major cause of absence from school and work. Endometriosis is often diagnosed 7 to 10 years after symptoms begin.

Mechanisms. Prostaglandin F2 alpha and E2 released from the secretory endometrium cause uterine hypercontractility, ischaemia and sensitisation of pain fibres. Secondary causes add inflammation, obstruction, adhesions or nerve involvement.

Classification. Primary or secondary. By severity: mild (daily activity unaffected), moderate (some limitation) and severe (incapacitating, with absence from work or school).

Temporal patterns. Primary pain starts just before or with the onset of flow, peaks in the first day, and settles within 72 hours. Pain that begins days before bleeding, lasts through the cycle, is new after age 25, or worsens progressively suggests secondary disease.

History

• Pain: onset relative to flow, duration, character, severity score from 0 to 10, radiation to back and thighs, response to analgesics, effect on daily life.
• Associated symptoms: nausea, vomiting, diarrhoea, headache and dizziness (usual with primary pain); dyspareunia, dyschezia, dysuria or haematuria with periods, infertility, chronic pelvic pain, heavy bleeding, intermenstrual bleeding, discharge (secondary causes).
• Menstrual history: age at menarche, cycle length, flow, regularity.
• Contraception: intrauterine device (copper device increases pain and bleeding), hormonal methods.
• Sexual and infection history, previous pelvic inflammatory disease, surgery, endometriosis in relatives.
• Previous treatments and effect: analgesics, hormonal therapy.
• Mood, anxiety, sleep, abuse, and school or work absence.
• Primary amenorrhoea or very short, painful periods with cyclical pain (outflow obstruction).

Examination

• Vital signs, BMI, abdominal examination for masses, tenderness or hernia.
• In sexually active women: speculum (discharge, cervical lesion, device threads) and bimanual (uterine size, fixation or retroversion, tenderness, uterosacral nodularity, adnexal mass, cervical motion tenderness).
• Girls who have not had intercourse: abdominal examination and inspection of the vulva and hymen, with no internal examination unless clinically necessary.
• Vaginal septum or bulging hymen.
• Back, hips and pelvic floor muscles when other pain is present.

Red flags

• Fever, offensive discharge or cervical motion tenderness (pelvic inflammatory disease).
• Positive pregnancy test with pain (ectopic pregnancy, miscarriage).
• Severe or rapidly progressive pain, new onset after age 25, or no response to 3 months of anti inflammatory treatment and hormonal treatment.
• Pelvic mass or ascites.
• Cyclical pain with primary amenorrhoea, or pain with a bulging hymen or vaginal swelling (outflow obstruction, haematocolpos).
• Dysuria or haematuria cyclical with menses (bladder endometriosis).
• Dyschezia with rectal bleeding during menses (bowel endometriosis).
• Pain after an intrauterine device insertion, or a displaced device.

Special groups. Adolescents: primary dysmenorrhoea is the usual cause, but persistent severe pain still needs ultrasound and consideration of an obstructive anomaly or endometriosis. Women over 40: adenomyosis and fibroids are more likely. Women with an intrauterine device: consider infection, expulsion and perforation.

Organised by mechanism.

Primary dysmenorrhoea. Excess endometrial prostaglandin production without pelvic pathology (the commonest cause in women under 25).

Secondary dysmenorrhoea, common

• Endometriosis: pain begins before flow, deep dyspareunia, dyschezia, dysuria, infertility, chronic pelvic pain.
• Adenomyosis: heavy painful periods, diffusely enlarged tender uterus, usually over age 35 and parous.
• Uterine fibroids, especially submucous: heavy bleeding and pain.
• Copper intrauterine device related dysmenorrhoea.
• Chronic pelvic inflammatory disease and endometritis.
• Endometrial polyp.

Secondary dysmenorrhoea, structural and obstructive

• Imperforate hymen, transverse vaginal septum, obstructed hemivagina with ipsilateral renal agenesis, non communicating uterine horn.
• Cervical stenosis after loop excision, cone biopsy or ablation.
• Intrauterine adhesions (Asherman syndrome).
• Adhesions after pelvic surgery or infection.

Other pelvic and non gynaecological causes

• Pelvic congestion syndrome, ovarian cysts including endometrioma.
• Interstitial cystitis (bladder pain syndrome) and urinary tract infection.
• Irritable bowel syndrome, constipation, inflammatory bowel disease.
• Pelvic floor myalgia and abdominal wall pain.
• Psychological factors, sexual abuse sequelae, depression and anxiety (amplifiers).

Serious causes

• Ectopic pregnancy and miscarriage.
• Pelvic inflammatory disease with tubo ovarian abscess.
• Ovarian torsion and ruptured endometrioma.
• Pelvic malignancy (ovarian cancer, uterine sarcoma).

Stepwise reasoning

1. Exclude pregnancy and infection when risk or symptoms are present.
2. Classify as primary or secondary from age at onset, timing, associated symptoms and examination.
3. In a typical primary pattern, start treatment without investigation and review response.
4. Image the pelvis, then consider MRI and laparoscopy, when features suggest secondary disease or treatment fails.

Tests

• Urine pregnancy test.
• Nucleic acid amplification tests for chlamydia, gonorrhoea, Trichomonas vaginalis and Mycoplasma genitalium, and vaginal swab for pH and microscopy when infection is suspected.
• Urine dipstick and culture.
• Full blood count and C reactive protein.
• Pelvic ultrasound (transvaginal when appropriate, transabdominal otherwise): endometrioma (ground glass cyst), adenomyosis (heterogeneous myometrium, asymmetric wall, globular uterus, subendometrial cysts), fibroids, hydrosalpinx, obstructive anomaly, haematocolpos, and the sliding sign for pouch of Douglas obliteration.
• MRI pelvis for suspected deep endometriosis, adenomyosis, obstructive anomaly or renal tract anomaly, and when ultrasound is inconclusive.
• Renal tract ultrasound with any Müllerian anomaly.
• CA 125 only with a pelvic mass, interpreted with menopausal status and ultrasound features (it is non specific and raised in endometriosis and menstruation).
• Diagnostic laparoscopy when imaging is negative and pain persists despite 3 months of treatment, and for excision of endometriosis.
• Hysteroscopy for suspected polyp, submucous fibroid or adhesions.

Limitations. A normal ultrasound does not exclude endometriosis, and superficial peritoneal disease is not visible on imaging. Pain severity does not correlate with disease stage. Treatment without imaging is reasonable in typical primary dysmenorrhoea, but failure of two treatments needs reassessment.

Immediate steps. Treat sepsis, ectopic pregnancy, torsion and obstructed anomaly with severe pain the same day. Provide analgesia and heat for all women.

General measures. Heat applied to the lower abdomen, regular exercise, and transcutaneous electrical nerve stimulation. Evidence for dietary supplements (vitamin B1, magnesium, omega 3 fatty acids) is limited.

Primary dysmenorrhoea, first line

• Ibuprofen 400 mg orally every 6 to 8 hours with food, maximum 2.4 g daily; start at the onset of pain or bleeding (or 1 to 2 days before expected menses if pain is predictable) and continue for 2 to 3 days. Avoid in peptic ulcer, renal impairment, heart failure and NSAID sensitive asthma; use the lowest effective dose; check renal function with prolonged use.
• Naproxen 500 mg orally twice daily with food, maximum 1 g daily same contraindications.
• Mefenamic acid 500 mg orally three times daily with food for up to 5 days, maximum 1.5 g daily; same contraindications.
• Paracetamol 1 g orally every 4 to 6 hours as an adjunct, maximum 4 g daily (3 g daily with chronic alcohol use, malnutrition or hepatic impairment; 15 mg/kg each dose in those under 50 kg).
• If no response after 3 menstrual cycles of full dose NSAID given early, change the NSAID once and then move to hormonal treatment.

Hormonal treatment (primary and secondary, first line when contraception is also wanted, or when NSAIDs fail)

• Combined oral contraceptive with 30 to 35 microgram ethinylestradiol, taken cyclically or continuously (tailored with 3 pack cycles to reduce bleeding days); contraindicated with migraine with aura, previous thromboembolism, smoking over age 35, uncontrolled hypertension and some cardiovascular disease.
• Levonorgestrel 52 mg intrauterine system, active for at least 5 years; spotting in the first 3 to 6 months.
• Etonogestrel implant (68 mg for 3 years) or depot medroxyprogesterone acetate 150 mg intramuscularly every 12 weeks (bone density loss with long use).
• Dienogest 2 mg orally once daily continuously (maximum 2 mg daily), particularly for endometriosis and adenomyosis; irregular bleeding is common in the first months.
• Norethisterone acetate 5 mg orally once daily, increased by 2.5 mg every 2 weeks to a maximum of 15 mg daily.

Secondary dysmenorrhoea, cause specific

• Endometriosis and adenomyosis: NSAIDs plus hormonal suppression (combined oral contraceptive, levonorgestrel intrauterine system, dienogest 2 mg orally daily, or norethisterone acetate 5 mg orally daily). Second line: leuprorelin 3.75 mg intramuscularly every 4 weeks for up to 6 months with add back norethisterone acetate 5 mg daily and bone density monitoring. Laparoscopic excision or ablation of endometriosis for failure of medical treatment, deep disease, endometrioma or infertility; hysterectomy for completed families with adenomyosis who fail treatment.
• Pelvic inflammatory disease: ceftriaxone 1 g intramuscularly once, doxycycline 100 mg orally twice daily for 14 days and metronidazole 400 mg orally twice daily for 14 days; review at 72 hours; admit for severe illness.
• Copper intrauterine device: NSAIDs, then switch to the levonorgestrel intrauterine system.
• Obstructive anomalies, cervical stenosis, polyps and submucous fibroids: surgical correction.
• Intrauterine adhesions: hysteroscopic adhesiolysis.
• Interstitial cystitis, irritable bowel syndrome and pelvic floor myalgia: treat the cause with specialist input.

Monitoring. Review after 3 months. Record pain scores from 0 to 10, days of absence and analgesic use. Check renal function and blood pressure with prolonged NSAID use, and bone density with prolonged depot medroxyprogesterone acetate or gonadotropin releasing hormone agonist use.

Referral and escalation. Refer to gynaecology for suspected endometriosis, adenomyosis, obstructive anomaly, pelvic mass, failure of two first line treatments over 3 to 6 months, or pain with fertility concerns. Refer urgently within 2 weeks for suspected cancer. Involve psychological and pain services for chronic pain with central sensitisation.

Admission criteria. Suspected ectopic pregnancy, torsion, pelvic inflammatory disease with systemic illness, and pain uncontrolled by oral analgesia.

Discharge and follow up. Most women are managed as outpatients. Provide a written analgesia plan and arrange review at 3 months.

Safety netting. Return for fever, heavy bleeding, severe or worsening pain, fainting, a positive pregnancy test, or no response to treatment.