Do I need to stop HRT before surgery?

Taking HRT and have an operation soon? What you need to know about hormones and surgery

• Major surgery can carry a risk of blood clots
• Find out which types of HRT are safe to take in the run up to surgery – and the ones you may have to temporarily pause
• Practical advice and tips on reducing your risk of clot post-surgery

If you are due to have an operation soon, you may be wondering whether you can keep taking your HRT in the run up to surgery and during your post-op recovery period.

Or perhaps you have already been told by your healthcare team you need to stop taking your HRT ahead of your operation and want to find out more.

Here, we take a closer look at the issue of the risk of blood clot associated with surgery, and what this means for you if you take HRT.

RELATED: HRT does explained

Blood clot risk and surgery explained

A blood clot occurs when blood thickens and clumps together.

Sometimes an unwanted clot can form in a deep vein, usually within your leg. This is known as a deep vein thrombosis (DVT). Occasionally this can lead to serious – and sometimes fatal – complications such as a pulmonary embolism (PE), where a clot breaks off and travels in the blood to the lungs.

Being immobile is a major risk factor for DVT, and it can be associated with long-haul flights due to sitting for long periods of time in a restrictive position. However, there is a higher risk of DVT and PE when you are admitted to hospital and are unable to move around much, particularly following major surgery to the abdomen, hip or knee.

DVT is a potential risk following any type of surgery, as the combination of immobility and the body’s response to surgical trauma can increase the likelihood of clot formation.

Does taking HRT increase my risk of getting a clot?

Most types of HRT are not associated with an increased risk of clot. Your risk of a clot depends on which type of HRT you take.

RELATED: Is HRT off limits if I’ve had a blood clot?

Transdermal oestrogen

If you take oestrogen through the skin via a patch, gel or spray (also known as transdermal HRT), there is no need to stop taking your hormones before or after surgery, regardless of the type of operation you have.

Oestrogen via a patch, gel or spray does not carry an increased risk of clot or stroke [1]. This is because oestrogen used in this way goes straight into your bloodstream, so bypasses your liver, which produces your clotting factors. This type of HRT is also safe for women to take, even if they have a high risk of clot or have had a clot in the past.

The bottom line? You can carry on taking transdermal HRT, and simply follow the general advice given to anyone for reducing risk of clot after your surgery [2].

If you are taking oral oestrogen

If you take the oestrogen part of HRT in tablet form, then there is a very small risk of clot. This is because when oestrogen is taken orally, it is metabolised in your liver, so stimulates your clotting factors [3].

Because of this slight risk, you may be asked to stop taking your oestrogen tablets four to six weeks before any major surgery. This may not be necessary for minor or laparoscopic surgery: you should discuss your individual risk of clot with your surgeon.

Because oral oestrogen does carry this small risk, it may be worth considering changing the way you take oestrogen in the future and switching to transdermal oestrogen.

Taking progestogens

Any increased risk of clot has also been shown to be related to the type of progesterone used.  There are two main groups of progesterone, which is the hormone you need to protect your uterus if you take oestrogen. They are:

• Progestogens, which refers to synthetic, or chemically created hormones
• Progesterone, which is the same as your natural hormone. When replaced as part of HRT is known as micronised or body-identical progesterone.

Studies have shown that there is no increased risk of clot with:

• Body-identical micronised progesterone, often known under the brand names Utrogestan, Gepretix and Prometrium [4]
• The Mirena coil: a hormonal intrauterine device commonly used for contraception but also for the progestogen part of HRT [5]. Although this does contain the progestogen levonorgestrel, there is very little absorption of the hormone into your bloodstream as it is released in your uterus.

There is a small risk of clot with the oral synthetic progestogens, which are found in some types of HRT. Examples of these include medroxyprogesterone acetate (MPA), dydrogesterone, levonorgestrel, or drospirenone. Patches containing a combination of oestrogen and progesterone contain the body identical oestrogen, but a synthetic progestogen so may be associated with a small increased risk of clot.

RELATED: Utrogestan (micronised progesterone) explained

What about testosterone?

There is no increased risk of blood clot if you are using testosterone through the skin in a gel or cream [6].

RELATED: The importance of testosterone for women

General benefits of HRT

If you’re able to continue taking HRT, there will be benefits to your overall health and wellbeing that will aid your recovery from surgery.

As well as not having to endure unpleasant menopausal symptoms, the oestrogen can aid your skin’s wound healing properties. HRT may also help give you energy and motivation for any physical rehabilitation that might be necessary after your operation.

And it’s always worth remembering that HRT optimises your future health, including helping to protect your bones, heart and blood vessels and brain.

RELATED: Perimenopause, menopause and HRT: everything you need to know

Talk to your surgeon

Some healthcare professionals are not aware of the evidence on the subject of HRT and blood clots. You may want to share this article with them as it contains helpful references to the evidence so you can discuss the best course of action for you.

How can I reduce my risk of clot after surgery?

Regardless of the type of HRT you take, it’s important to be aware of how you can reduce your risk of developing a clot following a major operation:

1. Discuss your individual risk of clot with your doctor prior to surgery, including:

Personal history of clot: inform your surgeon if you have ever experienced a blood clot in the past

Family history: share any family history of blood clots or clotting disorders, as genetic factors can play a significant role in your risk and your surgeon needs this information to provide the best care

Medication: mention if you are taking the contraceptive pill, or taking other medication that may affect your risk of clot.

2. If you have been prescribed blood-thinning medication such as heparin or warfarin, continue to take it as directed.

3. You may be advised to wear compression stockings during and after your surgery. These tight-fitting stockings may reduce risk of clot by compressing the veins in your legs to stimulate blood flow.

4. Keep well hydrated in the weeks before and after surgery.

5. Move around as often as you can post-surgery: you can do leg exercises such as circling your feet while in bed and be sure to shift position regularly. Taking regular short walks when you are able will also help.

References

1. Vinogradova, Y., Coupland, C., Hippisley-Cox, J. (2019), ‘Use of hormone replacement therapy and risk of venous thromboembolism: nested case – control studies using the QResearch and CPRD databases’, British Medical Journal, 364:k4810. doi: 10.1136/bmj.k4810. Erratum in: BMJ. 2019 Jan 15;364:l162]

2. Straczek, C. et al. (2005), ‘Estrogen and thromboembolism risk (ESTHER) study group. Prothrombotic mutations, hormone therapy, and venous thromboembolism among postmenopausal women: impact of the route of estrogen administration’, Circulation, 112(22):3495–500. doi: 10.1161/CIRCULATIONAHA.105.565556

3. Johansson, T. et al. (2024), ‘Contemporary menopausal hormone therapy and risk of cardiovascular disease: Swedish nationwide register based emulated target trial’, BMJ, Nov 27;387:e078784. doi: 10.1136/bmj-2023-078784

4. Scarabin, P.Y. (2018), ‘Progestogens and venous thromboembolism in menopausal women: an updated oral versus transdermal estrogen meta-analysis’, Climacteric, 21:4, 341-345. doi: 10.1080/13697137.2018.1446931

5. Van Hylckama Vlieg A., Helmerhorst F.M., Rosendaal F.R. (2010), ‘The risk of deep venous thrombosis associated with injectable depot-medroxyprogesterone acetate contraceptives or a levonorgestrel intrauterine device’, Arterioscler Thromb Vasc Biol, 30(11): 2297–2300. doi: 10.1161/ATVBAHA.110.211482

6. Glaser, R., Dimitrakakis, C. (2013), ‘Testosterone therapy in women: myths and misconceptions’, Maturitas, 74(3), pp.230–34. doi.org/10.1016/j.maturitas.2013.01.003