Reasoning GP · Algorithm · 1-page summary
Heavy menstrual bleeding — new presentation
For: women with heavy menstrual bleeding in primary care. Not for: pregnancy (bleeding in pregnancy algorithm), postmenopausal bleeding or bleeding on HRT (separate pathways), under-16s with first presentation (consider bleeding disorder).
Core rule: HMB is defined by impact, not volume. Check an FBC in all, ask about pregnancy plans, and start treatment today — but intermenstrual, postcoital or postmenopausal bleeding is a different route.
0Stop — call 999 now
- Torrential bleeding with tachycardia, hypotension, syncope or collapse → 999
- Positive pregnancy test with collapse, shoulder-tip pain or peritonism (ectopic) → 999
1Triage — what kind of bleeding?
| Pattern | Route |
|---|---|
| Regular heavy periods | HMB: FBC, treat today; examine if indicated |
| Intermenstrual / postcoital | Speculum, STI swab, screening status; persistent → outpatient hysteroscopy |
| Postmenopausal | 55 or over, not HRT → Suspected cancer pathway |
| Any chance of pregnancy | Pregnancy test first |
2Screen
- Abnormal cervix → consider Suspected cancer pathway (colposcopy)
- Pelvic mass not obviously fibroids, or ascites → Suspected cancer pathway
- IDA out of proportion → FIT; ≥10 µg Hb/g → colorectal Suspected cancer pathway
- Symptomatic anaemia → Same-day
- Bleeding since menarche + bleeding history → haematology (von Willebrand)
3Assess
☐ Impact, pattern, pain, bleeding history, drugs (DOAC, copper IUD) ☐ Pregnancy plans and contraception ☐ Pregnancy test ☐ FBC in all; consider ferritin ☐ TFTs only if thyroid symptoms
Examine if IMB/PCB, pain, pressure, suspected structural disease or before LNG-IUS. Pelvic US if palpable uterus, suspected mass, or examination inconclusive or difficult; TVUS for suspected adenomyosis (NG88).
4Classify
- No structural cause — regular, normal examination → treat on history.
- Fibroids — bulk, palpable uterus → TVUS; 3 cm or more or cavity distortion → consider gynaecology referral.
- Adenomyosis — pain, bulky tender uterus → TVUS.
- Endometrial pathology — IMB, obesity, PCOS, tamoxifen → hysteroscopy.
- Coagulopathy or drug — lifelong HMB, DOAC, copper IUD.
- Uncertain — treat, diary, review at about 3 months.
5Treat today — doses: SPC and local formulary
- LNG-IUS 52 mg first-line if not trying to conceive; allow at least 6 cycles.
- Else: tranexamic acid 1 g three times a day up to 4 days (max 4 g a day) ± mefenamic acid 500 mg three times a day; or CHC (UKMEC) or norethisterone 5 mg three times a day, day 5–26.
- Trying to conceive: tranexamic acid ± mefenamic acid only.
- Iron once daily or alternate days; Hb at 2–4 weeks.
6Refer routinely
- Consider gynaecology: treatment failure, fibroids 3 cm or more, persistent IMB (outpatient hysteroscopy) or endometrial risk.
- Suspected bleeding disorder or HMB on anticoagulation → haematology.
7Never reassure by
- A "normal" measured volume — impact defines HMB.
- A normal Hb when ferritin has not been considered.
- Periods explaining iron-deficiency anaemia without asking if they fit.
- A recent normal cervical screen when the cervix looks abnormal.
- Age under 55 in a woman with postmenopausal bleeding.
- A normal clotting screen in lifelong HMB.
8Safety-net — say it, then document it
999 “Call 999 if you faint, or you soak through pads every few minutes.” Same-day “Contact us today if heavy bleeding makes you dizzy or breathless, or you have a positive pregnancy test with bleeding or pain; or leg swelling, chest pain or breathlessness on tranexamic acid or the pill.” Review at about 3 months.
✓Safe to leave primary care only if — all five, documented
No block 0–2 row applies
Pregnancy excluded; bleeding pattern recorded
FBC done; iron started if deficient
Treatment started; pregnancy plans discussed
Review at about 3 months; safety-net given
Summary of the full Reasoning GP heavy menstrual bleeding algorithm, which holds the detail, examination, investigations and evidence. Sources: NICE NG88 (updated July 2026), NG12 (updated April 2026), CoSRH UKMEC, BSG; product SPCs. Clinical reference — follow local pathways; check doses in the SPC and your local formulary.