Abnormal Uterine Bleeding (AUB) = bleeding that differs in frequency, regularity, duration, or volume from normal menses. Peak prevalence is around menarche and perimenopause. Always exclude pregnancy first. In UK practice, use PALM–COEIN to classify causes and tailor management to pathology, age, anaemia, co-morbidities, and fertility wishes.

🔎 Definitions & Patterns

Menorrhagia (HMB): heavy/prolonged menstrual bleeding (patient-centred definition; often ≥80 mL, clots, flooding, anaemia).
Metrorrhagia: irregular/intermenstrual bleeding (IMB).
Menometrorrhagia: heavy + irregular.
Oligomenorrhoea: cycles >35 days; Polymenorrhoea: cycles <21 days.
Post-coital bleeding (PCB) and postmenopausal bleeding (PMB) are red flags.

📊 FIGO PALM–COEIN Classification

Structural (PALM)	Non-structural (COEIN)
Polyp	Coagulopathy (e.g., von Willebrand disease)
Adenomyosis	Ovulatory dysfunction (anovulation, PCOS, thyroid, hyperprolactinaemia)
Leiomyoma (fibroids)	Endometrial (primary disorder, infection)
Malignancy/Hyperplasia	Iatrogenic (IUDs, anticoagulants, HRT, steroids)
—	Not yet classified (rare/idiopathic)

🧠 Aetiology (organised by life stage)

Adolescents: anovulation (immature HPO axis), coagulopathy (ask about bleeding since menarche, epistaxis, easy bruising).
Reproductive age: pregnancy-related (miscarriage/ectopic), PCOS, thyroid disease, pelvic infection, polyps/fibroids, iatrogenic (copper IUD ↑ bleeding).
Perimenopause: anovulatory cycles, fibroids, polyps; consider endometrial hyperplasia.
Postmenopause: malignancy until proven otherwise (endometrium/cervix); HRT-related bleeding patterns.

🚩 Red Flags (urgent considerations)

Pregnancy symptoms (pain + bleeding, shoulder tip pain) → rule out ectopic.
PMB (any bleeding >12 months after LMP) → urgent suspected cancer referral.
PCB or persistent IMB
Iron-deficiency anaemia or haemodynamic instability
Risk factors for endometrial cancer: obesity, unopposed oestrogen, anovulation (PCOS), tamoxifen, Lynch syndrome.

🩺 History & Examination

History: cycle pattern, LMP, IMB/PCB/PMB, pain, clots/flooding, pregnancy risk, contraception, medications (anticoagulants/HRT), systemic (thyroid, prolactin), PCOS features, STI risk, coagulopathy history, cervical screening status, fertility wishes.
Exam: vitals, pallor, BMI, thyroid, abdominal masses; pelvic exam (speculum for cervix/PCB, bimanual for uterine size/tenderness); consider STI swabs.

🔬 Investigations (UK-oriented)

Always first: urine/serum β-hCG.
Bloods: FBC (anaemia), ferritin; TSH; consider prolactin; coagulation profile if bleeding since menarche or suggestive history.
Imaging: TVUS first-line for most AUB.
- PMB: endometrial thickness (ET) ≥4 mm → refer for biopsy/hysteroscopy; ET <4 mm with single episode may be observed.
- Fibroids: size, number, cavity distortion; MRI if adenomyosis or complex anatomy suspected.
Endometrial assessment: biopsy if age ≥45 with AUB; or <45 with risk factors (obesity, PCOS, tamoxifen) or persistent IMB/PCB; hysteroscopy for focal lesions (polyp/submucous fibroid).
Cervix: ensure up-to-date HPV/cytology; test for STIs where indicated.

🧭 Differential Diagnosis (selected)

Condition	Clinical Clues	Key Tests
Pregnancy/ectopic	Amenorrhoea + pain/bleeding	β-hCG, TVUS
PCOS (anovulatory AUB)	Oligo/anovulation, acne, hirsutism	Androgens, TSH, prolactin; TVUS
Fibroids	HMB, pressure, enlarged irregular uterus	TVUS ± MRI
Adenomyosis	Dysmenorrhoea, bulky tender “boggy” uterus	TVUS/MRI
Endometrial hyperplasia/cancer	PMB, obesity, unopposed oestrogen	TVUS (ET), hysteroscopy/biopsy
Cervical cancer	PCB, discharge	Speculum, HPV/cytology, colposcopy/biopsy
Coagulopathy	Bleeding since menarche, epistaxis	Coag screen, VWF assays
Thyroid disease	Weight change, fatigue/anxiety	TSH ± T4/T3
PID/endometritis	Pelvic pain, fever, discharge	NAAT swabs, TVUS
Iatrogenic	New meds (anticoagulants, HRT), copper IUD	Medication review, pregnancy test

🧰 Management Overview (aligns with UK/NICE principles)

Stabilise if haemodynamically unstable: IV access, fluids, cross-match; consider high-dose tranexamic acid and urgent gynae input.
HMB without identifiable pathology or fibroids <3 cm/not cavity-distorting:
- First-line: LNG-IUS (most effective, contraceptive benefit).
- Alternatives: tranexamic acid (menses only), NSAIDs (mefenamic), combined oral contraceptives, cyclical oral progestogens.
- Address iron deficiency (oral/IV), lifestyle, shared decision-making.
Fibroids ≥3 cm or cavity-distorting:
- Consider uterine artery embolisation, myomectomy, or hysterectomy (according to size, site, fertility wishes).
- GnRH analogues short-term for pre-op shrinkage or severe anaemia.
Focal pathology: polypectomy or hysteroscopic myomectomy.
Anovulatory AUB (e.g., PCOS): cycle regulation (COCP), cyclic/continuous progestin; weight optimisation; metformin (metabolic/ovulatory benefit).
Endometrial hyperplasia: progestin therapy (LNG-IUS preferred) with surveillance, or surgery depending on histology.
Malignancy: urgent gynae-oncology pathway for staging and definitive treatment.
Iatrogenic causes: adjust medications; switch copper IUD → LNG-IUS if appropriate.

💥 Acute Heavy Bleeding (non-pregnant)

Exclude haemodynamic instability and pregnancy.
Tranexamic acid (oral/IV) and NSAIDs if not contraindicated.
High-dose COCP or high-dose oral progestogen short course (per local guideline) to arrest bleeding.
Consider parenteral iron / transfusion if severe anaemia; urgent gynae review.

👩‍⚕️ Primary Care vs Urgent Referral (UK cues)

Urgent suspected cancer (2WW): all PMB; AUB with risk factors or abnormal endometrium; persistent PCB/IMB with abnormal cervix/cytology.
Routine gynae referral: failed first-line medical management, fibroids ≥3 cm/cavity distortion, suspected structural causes needing hysteroscopy.
Paediatrics/adolescents: heavy bleeding since menarche → consider haematology input.

📌 OSCE Exam Tips

Open with: “I will exclude pregnancy first and assess haemodynamic stability.”
Cover cycle pattern, IMB/PCB/PMB, anaemia symptoms, meds (anticoagulants/HRT), screening status, STI risk, fertility wishes.
State TVUS first-line; biopsy/hysteroscopy criteria (≥45 years, risk factors, persistent IMB/PCB; PMB with ET ≥4 mm).
HMB no pathology: LNG-IUS first-line; alternatives = tranexamic/NSAIDs/COCP/progestin.
Safety-net: red flags, iron therapy, follow-up of Hb and symptoms.

🔁 Follow-Up & Monitoring

Check Hb/ferritin after 6–12 weeks; assess symptom response and side effects.
Review contraception needs and fertility plans.
Escalate if medical therapy fails or new red flags develop.

🧩 Teaching Pearls

PMB is endometrial cancer until proven otherwise; TVUS ET ≥4 mm prompts tissue diagnosis.
In adolescents, think coagulopathy if bleeding began at menarche.
Copper IUD can worsen bleeding; LNG-IUS often cures HMB.
Anovulatory AUB (PCOS) increases unopposed oestrogen exposure → consider endometrial protection (progestin).

📚 References

Munro MG, et al. FIGO Classification (PALM–COEIN). Int J Gynaecol Obstet. 2011.
NICE NG88. Heavy Menstrual Bleeding: Assessment and Management. 2018 (and local pathways).
ACOG Practice Bulletin 128. Diagnosis of AUB. Obstet Gynecol. 2012.

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