About This Page
This is a clinician-written, evidence-based summary aligned to the 2026 MLA Content Map. It is intended for medical students and junior doctors preparing for the UKMLA. Always cross-reference with NICE guidance, local protocols, and clinical judgement.
The Bottom Line
- HMB = excessive menstrual blood loss affecting quality of life. Objective definition >80 mL/cycle but diagnosis is based on patient experience
- Causes (PALM-COEIN): structural — Polyp, Adenomyosis, Leiomyoma (fibroids), Malignancy; non-structural — Coagulopathy, Ovulatory dysfunction, Endometrial, Iatrogenic, Not classified
- First-line treatment: LNG-IUS (Mirena) — most effective medical treatment. Reduces bleeding by ~95%
- If LNG-IUS declined: tranexamic acid 1 g TDS during menses, mefenamic acid 500 mg TDS, or COCP
- Investigate if: age >45 or persistent IMB/PMB → endometrial biopsy to exclude malignancy
- Surgical options: endometrial ablation, myomectomy, or hysterectomy (definitive)
Overview
Heavy menstrual bleeding (HMB), previously termed menorrhagia, is defined as excessive menstrual blood loss that interferes with a woman's physical, social, emotional, or material quality of life. The traditional volume threshold of >80 mL/cycle is rarely measured in practice; the diagnosis is based on the woman's subjective assessment. NICE NG88 provides a structured approach to investigation and management, emphasising that treatment should be guided by whether a structural cause is identified (fibroids, polyps, adenomyosis) or whether bleeding is due to non-structural causes.
Epidemiology
HMB affects approximately 25–30% of women of reproductive age and is one of the most common reasons for referral to gynaecology. It accounts for ~20% of outpatient gynaecology referrals and is a common reason for hysterectomy. Prevalence increases with age, peaking in the perimenopausal years (40–50 years). Approximately 50% of women with HMB have no identifiable structural pathology (dysfunctional uterine bleeding).
Clinical Features
Symptoms
Heavy, prolonged menstrual periods — flooding, clots, needing to double up on protection
Periods lasting >7 days
Fatigue, dizziness, breathlessness (iron deficiency anaemia)
Intermenstrual bleeding (IMB) — bleeding between periods
Postcoital bleeding (PCB) — bleeding after sexual intercourse
Postmenopausal bleeding (PMB)
Dysmenorrhoea (pain suggests adenomyosis or endometriosis)
Signs
Pallor, tachycardia (iron deficiency anaemia)
Abdominal mass (large fibroids)
Bulky, tender uterus (adenomyosis)
Cervical polyp visible on speculum
Investigations
First-line
FBCCheck for iron deficiency anaemia. Treat if Hb low
Pelvic examinationBimanual — assess uterine size, tenderness, adnexal masses. Speculum — cervical pathology
Pelvic ultrasound (TVUSS)First-line imaging — assess uterine size, fibroids, endometrial thickness, ovarian pathology
Second-line
HysteroscopyIf USS abnormal or symptoms persist — direct visualisation of uterine cavity. Allows biopsy and polypectomy
Endometrial biopsyIf age >45, or persistent IMB, PMB, or treatment failure — to exclude endometrial hyperplasia/cancer
TFTsHypothyroidism can cause HMB
Coagulation screenIf HMB since menarche — consider von Willebrand disease or other coagulopathy
Specialist
Saline infusion sonographyIf submucosal fibroid or polyp suspected — not first-line (NICE NG88)
1
Medical — no structural cause or fibroids <3 cm
- 1st line: LNG-IUS (Mirena coil) — most effective. Reduces bleeding by ~95%. Lasts 5 years
- 2nd line (if LNG-IUS declined/unsuitable): tranexamic acid 1 g PO TDS during menses AND/OR mefenamic acid 500 mg PO TDS during menses
- 3rd line: combined oral contraceptive pill (cyclical or continuous) or cyclical oral progestogens (norethisterone 5 mg TDS, days 5–26)
- Injectable progestogen (Depo-Provera) may also be considered
2
Medical — fibroids ≥3 cm
- LNG-IUS first-line if uterine cavity not distorted
- Tranexamic acid and NSAIDs as adjuncts
- GnRH agonists (e.g., goserelin) — short-term use to shrink fibroids pre-surgery. Cause temporary menopause
3
Surgical options
- Endometrial ablation — destroys endometrium. Only if family complete
- Hysteroscopic myomectomy — for submucosal fibroids
- Myomectomy (open/laparoscopic) — preserves uterus for future fertility
- Uterine artery embolisation (UAE) — interventional radiology, shrinks fibroids
- Hysterectomy — definitive treatment. Consider if medical/conservative surgical options have failed or declined
Complications
- Iron deficiency anaemia: Most common complication — treat with oral ferrous sulphate 200 mg BD-TDS
- Impact on quality of life: Absence from work/school, social limitation, psychological distress
- Endometrial hyperplasia/cancer: Must be excluded in women >45 or with risk factors
UKMLA Exam Tips
- 1LNG-IUS (Mirena) = first-line treatment for HMB regardless of cause (unless distorted cavity) — very commonly tested
- 2Tranexamic acid is an antifibrinolytic — given ONLY during menses, not continuously
- 3PALM-COEIN classification of AUB — know the structural vs non-structural causes
- 4PMB = endometrial cancer until proven otherwise. Always investigate with USS and biopsy
- 5IMB and PCB need cervical examination — think cervical pathology (ectropion, cancer)
- 6HMB since menarche in a teenager → think von Willebrand disease or other coagulopathy
- 7Do NOT routinely measure serum ferritin — treat anaemia based on FBC (NICE NG88)
practicetest your knowledge on menorrhagia and abnormal uterine bleedingApply what you've learnt with UKMLA-style questions from the iatroX Q-Bank — obstetrics and beyond.
open q-bank