VTE and HRT (DRAFT)

Type of HRT

Transdermal estrogens  

Transdermal estrogens, alone or in combination at licensed doses, do not increase the risk of VTE above those of non-users in the low-risk population. 

People requesting HRT with risk factors for VTE are not the low-risk population and should be considered as a separate cohort. Please see below for further advice.  

Oral estrogens  

Oral estrogen use, alone or in combination, increase VTE risk 2-4 fold, and this risk is greatest in the first year after initiation.  

Vaginal estrogen  

Licensed doses of vaginal estrogens (estradiol, estriol) do not increase the risk of VTE.  

Progestogens 

Type of progestogen used can affect VTE risk.  

• Medroxyprogesterone acetate and Norethisterone are associated with higher VTE risk  

• Dydrogesterone and Micronised Progesterone (MP) are associated with a lower VTE risk in comparison  

• LNG-IUD does not increase VTE risk  

Tibolone  - the limited evidence available suggests that tibolone does not increase VTE risk, however, does increase stroke risk after 60y old.  

Specific considerations

*Lower risk progestogen options include micronized progesterone and 52mg LNG-IUD 

Recent surgery

Risk of VTE increases with surgical time and duration of anaesthesia. Immobilisation further increases VTE risk.  

Transdermal HRT is associated with a lower risk of VTE and some people will need to be switched from oral preparations to transdermal HRT to reduce their risk.  

Elective admissions for minor procedures, with thromboprophylaxis and no additional risk factors for VTE can continue their oral HRT. If additional risk factors are present women should be switched to transdermal HRT.   

If patients choose to switch back to oral HRT following recent surgery (within last 2 months), before switching back from transdermal to oral HRT you should:  

• Repeat VTE risk assessment to ensure no additional risk factors remain  

• Ensure 2 weeks of full mobilisation  

• If they are still using thromboprophylaxis, they should continue transdermal HRT and re-assess when completed. 

Obesity (BMI >30)

Risk of VTE increases with BMI and obese patients are more than twice as likely to develop VTE. Oral estrogen increases this risk further.  

BMI >30 patients should be given transdermal HRT. Lower risk progestogen options include MP and 52mg LNG-IUD

Previous VTE

Any previous VTE increases risk of recurrence. 

• Provoked by a transient risk factor – lower risk of recurrence 

• Unprovoked VTE – intermediate risk of recurrence  

• Provoked by a persistent or progressive risk factor – high risk of recurrence 

Those with a previous provoked VTE associated with a transient risk factor could consider transdermal HRT with a lower risk progestogen (MP or 52mg LNG-IUD). 

Those with a previous VTE outside of this should be referred to the complex menopause clinic for further assessment and consideration.  

Family History of VTE

Family history appears to be an independent risk factor for VTE outside of known syndromes. Patients should be offered transdermal HRT and a lower risk progestogen.  

Thrombophilia

Factor V Leiden and other thrombophilia's are associated with a significantly increased risk of VTE. If a personal history of VTE is present, they will need referral to Complex Menopause Clinic.  

If no personal history of VTE but with a positive thrombophilia screen – you may be able to consider transdermal HRT. If otherwise straightforward, advice and guidance can be sought from haematology prior to considering systemic HRT. They may require thromboprophylaxis. If needed, please refer to the complex menopause clinic.  

Licensed doses of vaginal estrogens do not further increase VTE risk and therefore can be prescribed.   

Post-partum

Can re-start their HRT when >6weeks post-partum.  

Age

>60 - offer transdermal HRT, refer to a menopause specialist if requiring higher than standard doses of HRT  

>70 - refer to complex menopause clinic.  

Referral

Please review the Specific Considerations table (above) and information on risk factors (above) to determine who should be referred to haematology or the complex menopause clinic, prior to starting HRT.

Referrals should be made via eRS to Gynaecology 

Haematology Advice & Guidance Service via eReferral 

Consider using Gynaecology Advice and Guidance via eRS if specific advice is required and not covered in these pages. 

Resources

For Patients:

Benefits and risks of HRT | Information for the public | Menopause: diagnosis and management | Guidance | NICE 

RESOURCES AND REFERENCES 

Exploring the potential for a set of UK hormone replacement therapy eligibility guidelines: A suggested proposal on the topic of venous thromboembolism - PubMed (nih.gov) 

02-BMS-ConsensusStatement-BMS-WHC-2020-Recommendations-on-HRT-in-menopausal-women-SEPT2023-A.pdf (thebms.org.uk) 

Menopause: diagnosis and management (nice.org.uk) 

Efforts are made to ensure the accuracy and agreement of these guidelines, including any content uploaded, referred to or linked to from the system. However, BNSSG ICB cannot guarantee this. This guidance does not override the individual responsibility of healthcare professionals to make decisions appropriate to the circumstances of the individual patient, in consultation with the patient and/or guardian or carer, in accordance with the mental capacity act, and informed by the summary of product characteristics of any drugs they are considering. Practitioners are required to perform their duties in accordance with the law and their regulators and nothing in this guidance should be interpreted in a way that would be inconsistent with compliance with those duties.

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