Dysmenorrhoea
Exam Tips
- Key discriminator: primary dysmenorrhoea starts soon after menarche with normal pelvic exam; secondary dysmenorrhoea often appears after years of painless cycles and has additional red-flag symptoms.
- Always exclude pregnancy first in reproductive-age patients with pelvic pain, even when dysmenorrhoea seems likely.
- NSAIDs work best when started before or at very start of bleeding because they block prostaglandin synthesis early.
- In OSCEs, explicitly ask about dyspareunia, intermenstrual/postcoital bleeding, discharge, bowel/urinary symptoms, and fertility intentions to screen for secondary causes and tailor treatment.
- See Figure: primary vs secondary dysmenorrhoea timeline comparison (history-pattern visual aid).
Definition
Dysmenorrhoea is painful menstruation, typically presenting as cramping lower abdominal pain just before or during menses. Primary dysmenorrhoea occurs without identifiable pelvic pathology (usually beginning 6-12 months after menarche once ovulatory cycles establish), whereas secondary dysmenorrhoea reflects an underlying condition such as endometriosis, adenomyosis, fibroids, pelvic inflammatory disease, or less commonly gynaecological malignancy.
Pathophysiology
In primary dysmenorrhoea, late luteal progesterone withdrawal triggers endometrial release of prostaglandins (especially PGF2alpha and PGE2), producing high-amplitude uterine contractions, vasoconstriction, transient myometrial ischaemia, and pain. Prostaglandin effects on other smooth muscle explain associated nausea, vomiting, diarrhoea, and headache; leukotrienes and vasopressin may further amplify uterine hypercontractility. Secondary dysmenorrhoea is driven by structural or inflammatory pelvic disease, so pain may extend beyond menstruation and often coexists with additional gynaecological symptoms. See Figure: prostaglandin-mediated uterine ischaemia pathway (core mechanism diagram).
Risk Factors
- Early menarche
- Heavy menstrual bleeding
- Nulliparity
- Family history of dysmenorrhoea
- Psychological stress
- Low BMI (<20 kg/m2)
- Cigarette smoking
- History of sexual abuse
- Risk factors for secondary causes (for example STI risk for PID, prior IUD insertion, risk profile for endometriosis/fibroids)
Clinical Features
Symptoms
- Cramping lower abdominal pain starting shortly before or at onset of menstruation
- Pain radiating to lower back or inner thighs
- Pain lasting up to about 72 hours and easing as flow progresses (typical primary pattern)
- Nausea, vomiting, diarrhoea, bloating, fatigue, headache, dizziness, irritability, low mood
- Features suggesting secondary disease: dyspareunia, heavy bleeding, intermenstrual or postcoital bleeding, persistent non-cyclical pelvic pain, vaginal discharge, rectal pain/bleeding
Signs
- Primary dysmenorrhoea: often normal abdominal and pelvic examination
- Secondary causes may show uterine/adnexal tenderness, palpable pelvic mass (for example fibroid), cervical excitation/discharge (PID), or fixed retroverted uterus/nodularity (possible endometriosis)
Investigations
Management
Lifestyle Modifications
- Use local heat (hot water bottle/heat patch) during painful days
- Regular aerobic exercise and sleep optimisation
- Smoking cessation and stress-reduction strategies
- Explain expected pattern and provide safety-netting for red flags (new non-cyclical pain, abnormal bleeding, dyspareunia, fever, positive pregnancy test)
Pharmacological Treatment
NSAIDs (first-line if no contraindication)
- Ibuprofen 400 mg orally three times daily with food, started at pain onset or up to 24 hours before menses
- Naproxen 500 mg initially, then 250 mg every 6-8 hours (or 500 mg twice daily depending on product regimen)
- Mefenamic acid 500 mg three times daily during menstruation
Avoid in active peptic ulcer disease, severe renal impairment, NSAID hypersensitivity, and use caution in asthma, cardiovascular disease, anticoagulant/SSRI use, and dehydration; counsel on GI bleeding risk and shortest effective duration.
Simple analgesia
- Paracetamol 1 g every 4-6 hours when required (maximum 4 g/day)
Use if NSAIDs are contraindicated/not tolerated or as adjunct; reduce maximum dose in low body weight/frailty and avoid overdose risk in liver disease/alcohol excess.
Hormonal suppression (if contraception acceptable or inadequate response to analgesics)
- Combined oral contraceptive pill, e. g. ethinylestradiol 30 micrograms with levonorgestrel 150 micrograms once daily (cyclical or extended regimen)
- Desogestrel 75 micrograms once daily (continuous progestogen-only pill)
- Levonorgestrel-releasing intrauterine system 52 mg device
- Medroxyprogesterone acetate depot 150 mg IM every 13 weeks
CHC contraindications include migraine with aura, current/past VTE or high VTE risk, severe hypertension, and smoking age >=35 years; assess UKMEC eligibility. Irregular bleeding is common early with progestogen-only methods; discuss fertility plans and bone health considerations for long-term depot use.
Surgical / Interventional
- Treat confirmed secondary cause when present (for example laparoscopic excision/ablation of endometriosis, myomectomy for symptomatic fibroids)
- Definitive surgery such as hysterectomy may be considered only in severe refractory secondary dysmenorrhoea after specialist assessment and completed family
Complications
- Reduced quality of life and limitation of daily activities
- School/work absenteeism and reduced academic/work performance
- Sleep disturbance and poorer mood during menses
- Higher rates of anxiety and depressive symptoms
- Possible persistent pain sensitisation beyond menstruation
Prognosis
Primary dysmenorrhoea is often long-term but commonly improves with age, after pregnancy, and with effective hormonal suppression. Prognosis is generally good with treatment adherence, but persistent or worsening pain should prompt reassessment for secondary pathology.
Sources & References
🏥BMJ Best Practice(1)
💊BNF Drug References(3)
- Flurbiprofen[management.pharmacological]
- Indometacin[management.pharmacological]
- Norethisterone[management.pharmacological]
✅NICE Guidelines(1)
- Dysmenorrhoea[overview]
📖Textbook References(1)
- Emergencies in - Obstetrics and Gynaecology, Second Edition (Stergios K. Doumouchtsis, S. Arulkumaran) (Z-Library).pdf(pp. 249, 250)[context]