Managing unscheduled vaginal bleeding in individuals using combined MHT

Initial investigation of unscheduled vaginal bleeding in an individual using combined menopausal hormone therapy (MHT) is only recommended if bleeding is heavy (includes clots or flooding), irregular or postcoital1, or the individual has an increased risk of endometrial cancer (eg obesity, diabetes, family history of endometrial or bowel cancer2).

Note: Prompt investigation of vaginal bleeding is only needed if bleeding is heavy, irregular, postcoital, or occurs in individuals at increased risk of endometrial cancer.

For most individuals who experience unscheduled vaginal bleeding after starting or changing MHT, investigations can be deferred until a change of therapy has been trialled for 8 to 12 weeks. Before changing therapy, check adherence and confirm correct use of current therapy (delayed dosing is a common cause of bleeding).

In cyclical combined MHT, if the expected withdrawal bleed occurs before day 10 of progestogen and has not settled within 2 to 3 months, endometrial protection against hyperplasia and cancer may not be adequate. Increase the duration of progestogen (eg from 10 days to 12 or 14 days, or occasionally 21 days) or increase the progestogen dose.

In continuous combined MHT, breakthrough bleeding is common in the first 3 to 6 months. It can be caused by an imbalance between estrogen and progestogen doses. A progestogen dose that is too low for the estrogen dose causes endometrial thickening; a progestogen dose that is too high for the estrogen dose causes endometrial atrophy.

Options for altering continuous combined MHT if bleeding has not settled within the first 3 months include:

Review 2 to 3 months after adjusting treatment. If irregular or unscheduled bleeding has still not settled, investigate and consider the need for referral.

Investigations include:

  • pelvic examination
  • cervical assessment (symptomatic Co-test), if a routine screen has not recently been undertaken
  • screen for sexually transmitted infection
  • pelvic (preferably transvaginal) ultrasound scan.

Transvaginal ultrasound detects endometrial thickness (which helps determine whether progestogen dose need to be increased [if endometrium is thick] or decreased [if endometrium is thin]) and the presence of focal abnormalities such as fibroids or endometrial polyps. Refer for hysteroscopy (and possible biopsy) if:

  • endometrial thickness is 4 mm or more
  • fibroids or endometrial polyps are present
  • bleeding fails to settle after changes to therapy.
1 Postcoital bleeding is unlikely to be related to menopausal hormone therapy (MHT) but requires assessment because it may be a sign of a comorbidity such as cervical cancer.Return
2 See the Cancer Australia website for information on Lynch syndrome, with hereditary risk of endometrial, bowel and other cancers.Return
3 If an ultrasound has been performed and atrophic endometrium was identified, the progestogen dosage should be decreased.Return