Do I need to stop HRT before 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

An estimated one in ten people undergo surgery in the UK every year.

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, balance takes 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.

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 cause of DVT and is occasionally 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/PE when you are admitted to hospital and are unable to move around much,  particularly following major surgery to the abdomen, hip or knee.

The good news is that DVT/PE can usually be prevented with medication, tight-fitting stockings and moving around.

Does taking HRT increase my risk of getting a clot?

This depends on what type of HRT you take.

Transdermal estrogen

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

Estrogen via a patch, gel or spray does not carry an increased risk of clot or stroke [1]. This is because estrogen used in this way goes straight into your bloodstream, so bypasses the 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 one in the past, so you can carry on taking it, and simply follow the general advice given to anyone for reducing risk of clot after your surgery [2].

If you are taking oral estrogen

If you take the estrogen part of HRT in tablet form, then there is a very small risk of clot for some women. This is because when estrogen is taken orally, it is metabolised in the liver, so stimulates the clotting factors.

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

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

Taking progestogens

Any increased risk of clot has been shown to be related to the type of progestogen used.  There are two main groups of progestogen, the hormone you need to protect your uterus if you take replacement estrogen. They are:

• progestins, which refers to synthetic, or chemically created hormones
• progesterone, your natural hormone, which 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, known under the brand name Utrogestan in the UK [3]
• the Mirena coil: a hormonal intrauterine device commonly used for contraception but also for the progestogen part of HRT [4]. Although this does contain the progestin levonorgestrel, there is very little absorption of the hormone into the blood stream as it is released in the uterus.
• synthetic progestogens given through the skin in combined HRT patches although it is worth pointing out trial numbers are small [5].

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.

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].

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 estrogen can aid the skin’s wound healing properties. HRT may also help give you energy and motivation to do the necessary physical rehabilitation, as well as keeping your mood and emotions in check during what can be a challenging time.

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

Talk to your surgeon

You might be surprised to know that some healthcare professionals are not aware of the up-to-date high-quality evidence on the subject of HRT and blood clots. You may want to share this leaflet 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. Mention if you are on 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 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. P.Y. Scarabin (2018), ‘Progestogens and venous thromboembolism in menopausal women: an updated oral versus transdermal estrogen meta-analysis’, Climacteric, 21:4, 341-345

4. 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.

5. 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].  

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