Menstrual Disorders — Dysmenorrhea, Menorrhagia, Amenorrhea & Treatment Guide — Symptoms, Causes & Treatment | MyMedicPlus

Menstrual disorders encompass a spectrum of abnormalities affecting the menstrual cycle's frequency, duration, volume, or associated symptoms. The normal menstrual cycle is 21-35 days in length; periods last 3-7 days; menstrual blood loss is 30-80 mL per cycle. The most common menstrual disorders are: dysmenorrhea (painful periods — affecting 50-90% of menstruating women); menorrhagia (heavy menstrual bleeding — objectively over 80 mL per cycle, though the NICE definition focuses on impact on quality of life rather than volume); amenorrhea (absence of periods — primary: no period by age 15; secondary: no period for 3+ consecutive months in a previously menstruating woman); irregular periods (oligomenorrhoea: cycles over 35 days; polymenorrhoea: cycles under 21 days); premenstrual syndrome (PMS); and premenstrual dysphoric disorder (PMDD — severe mood-related symptoms in the luteal phase, classified as a depressive disorder in DSM-5). Each disorder has distinct causes, investigations, and treatments, and many coexist — particularly in conditions such as polycystic ovary syndrome (PCOS) and endometriosis.

Primary dysmenorrhea (no identifiable pelvic pathology): caused by prostaglandin (PGE2 and PGF2-alpha) release from the endometrium during menstruation, causing myometrial ischaemia and painful uterine contractions; NSAIDs work by inhibiting prostaglandin synthesis (COX inhibition). Secondary dysmenorrhea (pelvic pathology): endometriosis (most important cause — retrograde menstruation causing ectopic endometrial implants in the peritoneum, ovaries, and fallopian tubes, causing cyclical pain); uterine fibroids (submucosal and intramural — distort the uterine cavity); adenomyosis (endometrial glands within the uterine muscle — causes heavy, painful periods in parous women aged 35-50); endometrial polyps; pelvic inflammatory disease (PID — ascending infection, Chlamydia trachomatis or Neisseria gonorrhoeae); and intrauterine device (non-hormonal copper IUD). Heavy menstrual bleeding (HMB) causes: uterine fibroids, adenomyosis, endometrial polyps, anovulatory cycles (PCOS, perimenopause), endometrial hyperplasia, coagulation disorders (von Willebrand disease — the most common inherited cause of HMB, affecting 1% of women). Amenorrhea causes: primary — chromosomal disorders (Turner syndrome, 45X), Müllerian agenesis, imperforate hymen, hypothalamic failure; secondary — hypothalamic (functional hypothalamic amenorrhea from weight loss/exercise/stress — GnRH suppression), hyperprolactinaemia (prolactinoma), thyroid disease, PCOS (anovulation), premature ovarian insufficiency, Asherman's syndrome.

Dysmenorrhea: lower abdominal cramping pain beginning 1-2 days before or at menstruation onset, lasting 12-72 hours; radiation to the lower back and inner thighs; associated nausea, vomiting, diarrhoea, headache, fatigue, and syncope in severe cases. Secondary dysmenorrhea from endometriosis additionally causes dyspareunia (deep pain during intercourse), dyschezia (painful defecation during menstruation), and chronic pelvic pain. Heavy menstrual bleeding: passing clots larger than a 50p coin (over 2 cm); soaking a pad or tampon every hour or less for several consecutive hours; significant anaemia symptoms (fatigue, breathlessness, palpitations, pallor); flooding (blood soaking through to clothing or bedding — socially debilitating). Amenorrhea: absence of periods; features of underlying cause — hot flushes and vaginal dryness (premature ovarian insufficiency or menopause); galactorrhoea (hyperprolactinaemia); weight loss, over-exercise, or stress (functional hypothalamic amenorrhea); hirsutism and acne (PCOS). PMDD: depressive mood, anxiety, irritability, mood swings, and affective lability exclusively in the luteal phase (days 14-28), with complete resolution by day 4 of the next cycle; causes significant functional impairment in work, relationships, and social life.

History: menstrual diary documenting cycle length, period duration, volume (number of pads/tampons used, clot passage), pain severity (numerical rating scale), impact on activities, and intermenstrual or post-coital bleeding. Pelvic examination: assess uterine size and tenderness; speculum examination for cervical abnormality. Transvaginal ultrasound (TVUS): first-line imaging — evaluates uterine size and shape, endometrial thickness, fibroid location and size, adenomyosis features (heterogeneous myometrium, myometrial cysts), and ovarian pathology. Blood tests: full blood count (haemoglobin and iron stores for HMB); pregnancy test (exclude ectopic pregnancy); hormonal profile for amenorrhea or oligomenorrhoea: FSH, LH, oestradiol, prolactin, TSH, free androgen index, AMH (ovarian reserve); coagulation screen (von Willebrand factor antigen and activity — screen all women with HMB from menarche). Hysteroscopy: direct uterine cavity visualisation — gold standard for intrauterine pathology (polyps, fibroids, adhesions); allows concurrent surgical treatment. Endometrial biopsy (Pipelle): for women over 40 with HMB or abnormal uterine bleeding — excludes endometrial hyperplasia and cancer. Laparoscopy: definitive diagnosis of endometriosis — direct visualisation and histological confirmation of ectopic endometrial tissue.

Primary dysmenorrhea: NSAIDs (ibuprofen 400-600 mg TDS or naproxen 500 mg BD) started 24-48 hours before anticipated menstruation onset and continued for the first 2-3 days — significantly more effective than paracetamol; combined oral contraceptives (COCs — reduce endometrial prostaglandin production, decrease menstrual volume, and regulate cycles); heat therapy; transcutaneous electrical nerve stimulation (TENS). Secondary dysmenorrhea from endometriosis: hormonal suppression — COCs (continuous/cycling), progestogens (norethisterone, medroxyprogesterone acetate, desogestrel), levonorgestrel IUD (Mirena — reduces pain and bleeding); GnRH agonists (goserelin, leuprorelin — 6-month courses, often with add-back HRT); dienogest (selective progestogen — endometriosis-specific). Heavy menstrual bleeding (first-line pharmacological): levonorgestrel intrauterine system (Mirena IUD) — reduces menstrual blood loss by 80-90% at 12 months; the most effective medical treatment for HMB; suitable for ≥ 5 years. Tranexamic acid (antifibrinolytic: 1 g TDS for first 4 days of menstruation — reduces blood loss by 30-50%); NSAIDs (mefenamic acid or ibuprofen — also reduce dysmenorrhea); COCs or progestogens. HMB surgical options: endometrial ablation (thermal balloon, radiofrequency — destroys endometrial lining; amenorrhoea in 30-40%, satisfaction over 90%; outpatient under local anaesthetic); hysteroscopic myomectomy (fibroid removal); transcervical resection of fibroid/polyp; hysterectomy (definitive, when family complete). Amenorrhea: treat underlying cause — oestrogen replacement for hypothalamic amenorrhea or POI; cabergoline/bromocriptine for hyperprolactinaemia; metformin or combined OCP for PCOS.

Heavy menstrual bleeding causing iron-deficiency anaemia: HMB is the most common cause of iron deficiency anaemia in premenopausal women — severe anaemia causes fatigue, breathlessness on exertion, palpitations, impaired cognitive function, reduced work capacity, and worsens existing cardiovascular disease. Untreated endometriosis causing infertility: moderate-severe endometriosis impairs fertility through tubal distortion, ovarian reserve reduction (endometrioma damage), and peritoneal inflammatory environment hostile to implantation; endometriosis is found in 40-50% of women investigating infertility. Recurrent miscarriage from submucosal fibroids or endometrial polyps. Endometrial hyperplasia or cancer from untreated anovulatory bleeding (unopposed oestrogen stimulation) — requires investigation and treatment (endometrial biopsy, progestogen therapy). Hypothalamic amenorrhea causing osteoporosis: oestrogen deficiency from prolonged amenorrhea causes bone mineral density loss — similar to early menopause.

NSAIDs started 1-2 days before expected menstruation onset prevent prostaglandin accumulation and are far more effective than waiting until pain is established. Combined oral contraceptives regulate cycle length, reduce menstrual volume by 40-50%, and reduce dysmenorrhea — particularly useful for women not yet planning pregnancy who wish to avoid monthly painful periods. Levonorgestrel IUD provides the most effective long-term management of HMB (80-90% reduction). Treat nutritional deficiencies: correct iron deficiency anaemia in women with HMB — ferrous sulfate 200 mg BD, and investigate and treat the underlying cause concurrently. Exercise: regular aerobic exercise reduces dysmenorrhea severity (comparable to NSAIDs in some RCTs) and reduces PMDD severity. Track cycles using apps (Clue, Flo) — a menstrual diary (3 months minimum) documents the pattern for accurate diagnosis and monitoring of treatment response. For PMDD: SSRIs (sertraline, fluoxetine, citalopram) taken continuously or luteal phase only are first-line pharmacological treatment — CBT is effective for mild-moderate PMDD.

See a GP urgently for: sudden severe pelvic pain in a woman of reproductive age (exclude ectopic pregnancy — serum beta-hCG essential); heavy menstrual bleeding soaking more than one pad/tampon per hour for several consecutive hours; postmenopausal bleeding (any vaginal bleeding after 12 months of amenorrhoea — requires urgent investigation to exclude endometrial cancer). See a GP within 1-2 weeks for: periods absent for 3 or more months with no obvious cause; dysmenorrhea significantly affecting daily life, school, or work despite NSAIDs; intermenstrual or post-coital bleeding; or suspected iron deficiency anaemia. Request gynaecology referral for: suspected endometriosis (deep dysmenorrhea, dyspareunia, dyschezia); heavy periods unresponsive to medical treatment; irregular cycles with signs of PCOS or hormonal disorder; and primary amenorrhoea (no period by age 15).