Synopsis
Provide dose-proportionate endometrial protection during systemic oestrogen and investigate unscheduled bleeding using the April 2026 NICE position and May 2026 BMS risk, timing and ultrasound thresholds.
- Anyone with a uterus using systemic oestrogen needs a monthly progestogen dose matched to the oestrogen dose; route of oestrogen does not remove this requirement.
- For sequential HRT, provide at least 12 days of micronised progesterone or 10 days of norethisterone or medroxyprogesterone acetate in each 28-day cycle.
- The oral micronised-progesterone licence provides 200 mg at bedtime on days 15 to 26, or 100 mg at bedtime on days 1 to 25; take it away from food.
- BMS supports any 52 mg levonorgestrel IUD for five years of HRT endometrial protection, while the Mirena product licence for this indication remains four years.
- Bleeding is common during the first six months after starting systemic HRT or within three months after a dose or preparation change; NICE's April 2026 update advises prompt help beyond these windows.
- In a low-risk patient within a settling window, check adherence, examination findings and proportional progestogen, then adjust treatment for up to six months in total.
- Arrange urgent TVUS within six weeks when bleeding first presents more than six months after starting or more than three months after a change, or sooner for heavy or prolonged bleeding or two minor risk factors.
- On a fully visualised uniform endometrium, more than 4 mm with continuous combined HRT or more than 7 mm with sequential HRT triggers urgent cancer-pathway endometrial assessment.
Key red flags
Haemodynamic compromise, syncope, chest pain, breathlessness or ongoing flooding requires emergency assessment rather than routine alteration of progestogen.
One major endometrial-cancer risk factor—including BMI at least 40 kg/m², Lynch or Cowden syndrome, or a major duration of under-opposed systemic oestrogen—requires an urgent suspected-cancer pathway regardless of bleeding timing or volume.
Three minor risk factors, including baseline BMI 30 to 39 kg/m², diabetes, polycystic ovary syndrome or shorter-duration endometrial under-protection, also require urgent suspected-cancer referral.
Prolonged, heavy, clotting or near-daily bleeding for four weeks warrants urgent transvaginal ultrasound even during an expected settling interval.
A suspicious cervix, postcoital bleeding, pelvic mass, persistent discharge or focal pain requires assessment of non-endometrial causes in parallel.
Investigation priorities
Place bleeding relative to initiation, changes, cyclic withdrawal and actual hormone exposure.
Management branches
Systemic oestrogen is prescribed to a person with a uterus.
- Confirm oestrogen type and dose, actual use, uterine anatomy and whether treatment is sequential or continuous combined.
- Provide at least the guideline minimum cyclic days or an adequate daily continuous progestogen dose, increasing opposition when oestrogen is high dose.
- If using a 52 mg LNG-IUD, record insertion date and counsel that the supported five-year HRT interval differs from the Mirena four-year licence and eight-year contraceptive licence.