Overview
Heavy menstrual bleeding (HMB) is defined as excessive menstrual blood loss that interferes with a woman's physical, social, emotional, or material quality of life. Historically defined by objective blood loss exceeding 80 mL per cycle, this quantitative threshold has been replaced by a patient-centred, symptom-based definition in contemporary practice.
The FIGO PALM-COEIN classification system (introduced 2011, widely adopted) provides a structured framework for categorising AUB aetiology. It accepts that multiple causes may coexist and that structural lesions may be present in asymptomatic women. PALM causes are identified by imaging and histopathology; COEIN causes by history and targeted investigation.
PALM-COEIN Classification
Structural Causes (PALM)
| Category | Key Features |
|---|---|
| P - Polyp (AUB-P) | Common; incidence increases with age; causes intermenstrual and heavy bleeding; frequently coexists with fibroids; ~1.7% malignancy risk in premenopausal women with AUB; larger pedunculated polyps may undergo ischaemic necrosis |
| A - Adenomyosis (AUB-A) | Endometrial glands and stroma within myometrium; associated with HMB and dysmenorrhoea; diffuse uterine enlargement; often coexists with endometriosis and fibroids; myometrial cysts are the most specific TVUS criterion; asymmetric myometrial thickening/heterogeneity and "Venetian blind" shadowing are suggestive |
| L - Leiomyoma (AUB-L) | Submucosal and intramural subtypes most associated with HMB; mechanism involves disrupted haemostasis and vasoactive growth factor release; FIGO leiomyoma subclassification (types 0-8) defines cavity relationship |
| M - Malignancy and Hyperplasia (AUB-M) | Endometrial carcinoma or hyperplasia; variable bleeding patterns (IMB, frequent, heavy, or prolonged); must be excluded in women ≥45, with risk factors, or with failed treatment |
Non-Structural Causes (COEIN)
| Category | Key Features |
|---|---|
| C - Coagulopathy (AUB-C) | Present in ~13% of women with HMB; von Willebrand disease is most common; suspect if HMB since menarche, family history of bleeding disorder, or personal history of epistaxis, easy bruising, minor wound bleeding, or oral/GI bleeding |
| O - Ovulatory Dysfunction (AUB-O) | Anovulation → unopposed oestrogen → endometrial hyperplasia → erratic heavy bleeding; common at extremes of reproductive life (adolescence, perimenopause), PCOS, thyroid disorders, hyperprolactinaemia |
| E - Endometrial (AUB-E) | Intrinsic endometrial haemostatic defects; excess vasodilators (PGE2, prostacyclin I2) or deficiency of vasoconstrictors (PGF2α, endothelin-1); abnormal fibrinolysis; diagnosis of exclusion in ovulatory women with structurally normal uterus |
| I - Iatrogenic (AUB-I) | Exogenous hormones (COC, progestogens, HRT), anticoagulants, copper IUD; breakthrough bleeding in first 1-3 months of hormonal contraception occurs in 30-40% of users and is usually self-limiting |
| N - Not Yet Classified (AUB-N) | Rare or poorly understood causes; includes chronic endometritis, arteriovenous malformations |
Clinical Assessment
Menstrual History
Document: - Cycle frequency, regularity, and duration of flow - Estimated blood loss: pad/tampon usage, flooding, clot passage - Associated symptoms: dysmenorrhoea, IMB, postcoital bleeding, pelvic pressure - Quality-of-life impact - Contraceptive use and fertility intentions - Personal and family history of bleeding diathesis - Thyroid and other systemic symptoms - Risk factors for endometrial pathology (obesity, PCOS, diabetes, tamoxifen use, Lynch syndrome family history)
Pictorial Blood Assessment Chart (PBAC)
The PBAC is a validated semiquantitative tool for estimating menstrual blood loss:
$$\text{PBAC score} = (\text{lightly soiled} \times 1) + (\text{moderately soiled} \times 5) + (\text{heavily soiled} \times 20) + (\text{small clots} \times 1) + (\text{large clots} \times 5)$$
A PBAC score $\geq 100$ per cycle correlates with objective blood loss $> 80\ \text{mL}$ and supports the diagnosis of HMB. Useful for baseline documentation and monitoring treatment response.
Investigations
| Investigation | Indication / Notes |
|---|---|
| Full blood count | All women with HMB; assess for iron deficiency anaemia |
| Ferritin | More sensitive marker of iron stores |
| TVUS | First-line imaging; characterises uterine morphology, endometrial texture, adnexal pathology |
| Sonohysterography (SHG) | Saline-infusion; superior to TVUS alone for intrauterine pathology (polyps, submucosal fibroids, adhesions); indicated when endometrium is irregular or poorly visualised on TVUS |
| Hysteroscopy | Diagnostic and therapeutic; gold standard for intracavitary pathology |
| Endometrial biopsy | Indicated: age ≥45; treatment failure; risk factors for endometrial cancer; persistent IMB; abnormal TVUS; erratic bleeding with obesity/PCOS/tamoxifen use. Outpatient Pipelle sensitivity ~90% for endometrial carcinoma. Avoid endometrial ablation without prior histological exclusion of hyperplasia/malignancy |
| Coagulation screen | VWF antigen/activity, Factor VIII, ristocetin cofactor; indicated if personal/family bleeding history or HMB since menarche |
| TFTs, prolactin | If ovulatory dysfunction suspected |
| Chlamydia PCR | Consider with IMB, adolescents, or non-monogamous relationships |
| MRI pelvis | Second-line; better characterisation of adenomyosis, multiple/large fibroids, surgical planning; not useful for endometrial polyp assessment |
Medical Management
First-Line Options
| Agent | Mechanism | Dose / Regimen | Blood Loss Reduction | Notes |
|---|---|---|---|---|
| LNG-IUS 52 mg | Local progestogen → endometrial decidualisation and atrophy | Intrauterine; licensed 5 years (evidence supports ≥7 years) | 75-96% reduction; approaches or equals ablation | Most effective medical option; more cost-effective than other medical therapies and ablation; treats adenomyosis and hyperplasia without atypia; counsel about irregular spotting for first 3-6 months. The 13.5 mg LNG-IUS is not licensed for HMB treatment |
| Tranexamic acid | Antifibrinolytic; inhibits endometrial fibrinolysis | 1 g orally three times daily during menstruation (up to 5 days) | ~50% reduction | Non-hormonal; suitable for women wishing to conceive; contraindicated with personal history of thromboembolism |
| NSAIDs (mefenamic acid, ibuprofen) | Inhibit prostaglandin synthesis; alter thromboxane A2/prostacyclin balance | Mefenamic acid 500 mg or ibuprofen 400 mg three times daily during menstruation | 20-40% reduction | Also relieves dysmenorrhoea; safe in women wishing to conceive; GI side effects possible |
| COCP | Stabilises endometrium via combined oestrogen-progestogen | Standard cyclical or continuous use | ~40-50% reduction | Reduces dysmenorrhoea; added contraceptive benefit; contraindicated if oestrogen contraindications present |
| Cyclical norethisterone | Progestogen → opposes oestrogen, stabilises endometrium | 5 mg three times daily, days 5-26 of cycle (21-day course) for ovulatory HMB | Effective for ovulatory HMB | Shorter courses (14 days, e.g., days 15-26) are only appropriate for anovulatory cycles; ineffective for ovulatory HMB if given for fewer than 21 days per cycle |
Second-Line Options
| Agent | Mechanism | Notes |
|---|---|---|
| GnRH agonist + add-back therapy (e.g., leuprorelin, goserelin) | Pituitary downregulation → hypo-oestrogenic state → amenorrhoea | Use ≤6 months without add-back; add-back HRT (low-dose oestrogen-progestogen or tibolone) mandatory beyond 6 months to protect bone density; benefit does not persist after cessation; use as short-term bridge or preoperative adjunct |
| Depot medroxyprogesterone acetate (DMPA) | Continuous progestogen → endometrial atrophy; amenorrhoea in many | Alternative when LNG-IUS not tolerated; unpredictable unscheduled bleeding in some |
Preoperative use of GnRH agonists: - Correct anaemia before surgery - Reduce uterine/fibroid volume to facilitate hysteroscopic resection or laparoscopic myomectomy - Shrink fibroids before hysterectomy
Special population - coagulopathy (VWD): Desmopressin at onset of menses is highly effective; tranexamic acid, COCP, and LNG-IUS also reduce blood loss; haematology co-management recommended.
Surgical Management
Endometrial Ablation
Destroys the endometrium to reduce or eliminate menstrual loss. Second-generation (non-resectoscopic) techniques (microwave ablation, thermal balloon, NovaSure® impedance-controlled bipolar) are preferred over first-generation hysteroscopic techniques due to equivalent efficacy with improved safety and shorter operating time.
Patient Selection:
| Criteria | Detail |
|---|---|
| Completed family | Absolute requirement |
| HMB refractory to or unsuitable for medical therapy | - |
| Normal or near-normal uterine cavity | No significant submucosal fibroids causing major cavity distortion |
| Endometrial histology: hyperplasia and malignancy excluded | Biopsy mandatory prior to ablation |
| No desire for future fertility | Not a reliable contraceptive; pregnancy after ablation carries risk of placenta accreta spectrum |
Absolute Contraindications:
| Contraindication |
|---|
| Desire for future pregnancy |
| Current or suspected endometrial carcinoma or atypical hyperplasia |
| Active pelvic infection |
| Significant cavity-distorting submucosal fibroids |
| Uterine anomalies incompatible with device deployment |
| Previous classical (vertical) uterine incision (device-dependent) |
Ablation does not adequately treat endometrial hyperplasia or malignancy and precludes adequate future endometrial surveillance. Patient satisfaction is high (~80%), but 20-30% of women ultimately require further intervention, including hysterectomy.
Myomectomy
Indicated for symptomatic fibroids with preserved fertility intent. Route depends on fibroid location, size, and number:
| Approach | Indication |
|---|---|
| Hysteroscopic | Submucosal fibroids (FIGO types 0, 1, 2); most effective for HMB from intracavitary fibroids |
| Laparoscopic | Intramural or subserosal fibroids; appropriate for fibroids up to ~8-10 cm in experienced hands |
| Open (abdominal) | Large, multiple, or complex fibroids; when laparoscopic approach not feasible |
Myomectomy does not guarantee resolution of HMB if other contributing causes coexist. Fibroid recurrence occurs in ~20-30% within 5 years. LNG-IUS expulsion rates are higher with fibroids >3 cm (15.4%) versus <3 cm (6.3%).
Hysterectomy
Definitive cure for HMB; highest long-term satisfaction rates. Reserve for women who have completed their family and have failed or declined medical and conservative surgical options, or where concurrent pathology (adenomyosis, large fibroids) makes conservative management inappropriate.
| Route | Notes |
|---|---|
| Laparoscopic (total or subtotal) | Preferred where feasible; reduced morbidity, shorter recovery |
| Vaginal | Suitable when uterus mobile and not excessively enlarged |
| Abdominal (open) | When other routes not possible (large uterus, adhesions, concurrent procedures) |
Subtotal hysterectomy preserves the cervix (cervical screening must continue). Bilateral salpingo-oophorectomy is not routinely recommended in premenopausal women; requires specific indication and careful surgical menopause counselling.
Complications of Untreated HMB
- Iron deficiency anaemia (most common systemic complication)
- Impaired quality of life, social and occupational dysfunction
- Delayed diagnosis of underlying malignancy or coagulopathy
- Subfertility if underlying pathology is untreated
Counselling Points
- Validate the woman's experience; reassure that HMB is common and often does not indicate serious pathology
- Discuss the PBAC as a useful self-monitoring tool
- Present all treatment options (medical, hormonal, surgical) with efficacy, side effects, reversibility, and effect on fertility
- LNG-IUS: counsel about irregular spotting for up to 6 months; amenorrhoea is a common expected outcome and should be framed positively
- Endometrial ablation: not a contraceptive; pregnancy after ablation carries risk of placenta accreta spectrum - reliable contraception must be used
- Hysterectomy: irreversible but curative; discuss surgical risks (bladder/bowel injury, haemorrhage, VTE, anaesthetic risk); subtotal hysterectomy requires ongoing cervical screening
- Address fertility preferences explicitly before any surgical option
- Coagulopathy (especially VWD): desmopressin, tranexamic acid, LNG-IUS, and COCP are all effective; haematology co-management recommended
- Acknowledge cultural and personal values in shared decision-making
Medicolegal and Ethical Considerations
- Failure to investigate for malignancy is a significant medicolegal risk; endometrial biopsy is mandatory in women ≥45 or with risk factors before empirical medical treatment that may mask underlying pathology
- Endometrial ablation in undiagnosed hyperplasia or malignancy is a serious adverse outcome; histological exclusion prior to ablation is non-negotiable
- Informed consent for surgical procedures must include alternatives, success rates, and specific complications (e.g., haematometra post-ablation, risk of conversion to hysterectomy)
- Advise that ablation does not guarantee amenorrhoea and hysterectomy may still be required
- Documentation of failed treatments, investigations, and shared decision-making is essential
- Women who decline investigation or treatment retain that right; document counselling and advise regarding ongoing surveillance if endometrial pathology risk factors are present
- In adolescents with HMB: prioritise coagulopathy screening before attributing bleeding to anovulation; structural causes are uncommon in this age group; COEIN aetiologies predominate