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sMater | Dr Caroline Wilson | VTE in Pregnancy

• Mater • Season 2 • Episode 22

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On this episode of sMater, Dr Caroline Wilson discusses Venus Thromboembolism (VTE), which continues to be a leading cause of maternal death.

As an obstetric physician and haematologist at Mater Hospital Brisbane, Caroline discusses risk factors, symptoms and treatment options for VTE during pregnancy.

For more information on the Royal College of Obstetricians and Gynecologists guideline, visit: gtg-37a.pdf (rcog.org.uk)

GP Education activity log:
  Podcast title - sMater: VTE in Pregnancy
  Provider - Mater Misericordiae Ltd
  Date published - September 13, 2024
  Certificate of completion - click here

To learn more about Mater, visit https://www.mater.org.au/

Hello and welcome to this episode of sMater. A podcast by clinicians for clinicians brought to you by Mater, an Australian leader in healthcare for more than a century. My name is Jillian Whiting and we're coming to you from Meanjin the land on which this podcast is being recorded. Hello I'm Maggie Robin, Community GP rural GP obstetrician at Beaudesert Hospital and coordinator of Mater's GP shared care education program. In this episode we're talking about Venus Thromboembolism during pregnancy with Dr Caroline Wilson. Caroline is an obstetric physician and hematologist at Mater Hospital South Brisbane. She's joining us to talk about VTE which remains a leading cause of maternal mortality and morbidity.

We are Mater, We are Mater, We are Mater, This is sMater.

Hi Caroline, welcome to sMater. Thanks for having me. As I mentioned VTE has been the leading cause of direct maternal death and worldwide there's been no consistent decrease in mortality over the past 20 years. What are your thoughts on that? Look I think it's really difficult to put that down to one single thing. We have risk prediction algorithms and guidelines that we use to predict who's at risk of Venus Thrombolic disease and therefore who should get prevention treatment for that but I think those risk prediction models have not really been prospectively validated and even if we did have that data I think maybe those models aren't the best to define risk of VTE. Maybe they're not being applied as they are intended and also the demographics of women are sort of changing, becoming more obese and overweight and maybe we're becoming older by the time we have children so I think that's multifactorial. I think furthermore to that even if you have the best risk predictor model, 30% of people who have a VTE event in pregnancy or postpartum doesn't have any classical risk factors so even if we have the best ever model in the world to try to predict and guide us on what to do we're going to miss 30% of those women anyway because they don't have traditional risk factors other than pregnancy so I think we should cut ourselves some slack on that.

What are the signs and symptoms of VTE?

That depends on the site. If you have a deep vein thrombosis mostly affecting the lower limb but in pregnancy often the more proximal veins of the lower limb generally the symptoms would be redness heat and pain and swelling. If you have a clot in the lungs so pulmonary embolism then usually the symptoms would be breathlessness which is very common in pregnancy anyway. Sometimes hemoptysis not very commonly and just more of a Tachycardia than your baseline during pregnancy but again very non-specific symptoms in a pregnant woman.

Caroline you mentioned that a third of women will have no risk factors but I guess that means that 2/3 will. What sort of risk factors or red flags should GP's be looking out for?

So the most important risk factor out of every single one on all those algorithms is a past history of VTE so I would take every single past history of VTE seriously and then assess each one on their merits so almost all previous VTE I would give prevention do anticoagulant during pregnancy sometimes if it's provoked by a major operation I would consider not doing it but in most cases I actually just give prevention dose anti-coagulant during pregnancy which is usually prevention dose Clexane in know setting.

Any other risk factors?

Yes, there is a number of smaller risk factors and some of them last throughout pregnancy until the postpartum period and some of them just affect a trimester or postpartum so the other major risk factors are a very strong found the history of of VTE which you can normally ascertain from the patient. I don't particularly use thrombophilia too much unless it's an acquired thrombophilia like antiphospholipid syndrome because generally a thrombophilia without a strong family history is actually not that helpful anyway so I don't personally do that much thrombophilia testing and treating depending on the scenario but I don't find those tests particularly helpful unless it's a known thrombophilia that that individual has been diagnosed with rather than just a family history if that makes sense so if you had someone who perhaps had a history of a DVT in a relative you wouldn't be necessarily going and doing an extended I wouldn't thrombophilia screen on them I would almost not because let's say you have someone who has a family history of clots and the mom had a clot and she has Factor V Leiden and then that patient doesn't have Factor V Leiden that doesn't mean oh well you'll be right then so I place a lot more weight on the personal on the patient's history and the family history rather than the individual gene test.

So age and High BMI and I almost always refer to the RCOG guidelines. I probably just don't follow them to the absolute tee but if you're going to refer to anything you just need to pick a guideline and follow it so I personally use the RCOG guidelines which is the British group and they very clearly say previous event other than provoked by major surgery some intermediate and some sometimes risk factors for example inflammatory bowel disease that's out of control that should have treatment while they're having a flare and then there's a number of other smaller risk factors like IVF in the first trimester, multi parity, high BMI,

smoking that together if you have enough of those things would mean that you should have thromboprophylaxis but I don't think everyone needs to remember every single thing and what the risk ratio is of each one I think we can just be kind to ourselves and refer to the algorithms and then you've got something to base your practice on.

What's the process for a woman no personal history family history VTE but she may some have some other red flags? So if they've got other risk factors again I would just apply an algorithm which like I said I use the RCOG ones because they're quite clear and they have a single page flow diagram of what to use and I would just apply that sometimes if the reason why they would qualify is a number of the smaller risk factors I would take that with a grain of salt because I think the most important risk factors are the are the ones higher up in the algorithm but you'd never be in trouble for following an algorithm and following it well.

So if we follow an algorithm and the algorism suggests that this person might need Thromboprophylaxis what are we looking at starting and at what gestation and what dose? So the risk for thrombosis during pregnancy is obviously higher in the postpartum setting but during pregnancy it's actually the same in each trimester so I in most cases would either start at the time of pregnancy diagnosis or in the postpartum setting so I don't really start halfway through and so those women should be started on Clexane and they should be started at a prophylactic intensity dose which again evidence-free zone because it's VTE and its pregnancy but I would usually start 40mg per day if they've got a normal BMI and above that it would just be weight based but
somewhere around 60mg if they're higher BMI.

Venus Thromboembolism complicates more than one in every 1,000 births. While there is a risk during the third trimester the greatest risk is in the weeks immediately after birth. The recurrence rate during the postpartum period is between 2 and 11% making it imperative the patients monitor symptoms closely until they are 13 to 18 weeks postpartum.

A lot of patients are concerned about going on Clexane because of potential risks are there any risks we should counsel women about?

I think when we're starting anticoagulation we should always warn women about bleeding risk the risk is very low with that prophylactic intensity dose just like any medication you can have an allergic reaction to it but thankfully it's quite low with Clexane that risk and there's no fetal concern so it's not going to cross the placenta and cause any harm to baby and we can reassure women of that.

Caroline how long after birth is Clexane required and is there any other postnatal therapy?

It's case dependent. I would usually continue it for most cases would be six weeks postpartum unless of course they were already on either prophylactic or therapeutic intensity anticoagulation before the pregnancy.

So in those women I would usually especially if they've seen a hematologist I would generally revert to what they were on prior to pregnancy so if it was prophylactic intensity dose of a medication I would continue that prophylactic intensity treatment for longer. Usually what we can use for prophylaxis is usually Clexane while they're breastfeeding but there is some emerging data about Rivaroxaban being safe in breastfeeding it seems to be quite safe but only a few small cases so I just discuss pros and cons of that with women if they are going to breastfeed and if they elect to have Rivaroxaban as their treatment rather than Clexane. I would not start it for the first few weeks postpartum and I don't usually use it if the baby is premature because of risk of bleeding for the baby just because it's quite limited case numbers and because it's an unknown and I just feel like that premature baby in the nursery doesn't need another thing. So I just try to avoid in those settings but it's completely not evidence based. It's evidence free zone just like most things that we do in pregnancy.

So for those people you'd recommend Clexane for a couple of weeks and then switch to Rivaroxaban. Yes. Okay and dose of Rivaroxaban? It depends so if you're on therapeutic dose it would be 20mg a day and they don't need that initial higher dose we usually use outside pregnancy the higher dose of Rivaroxaban when we first start Rivaroxaban is not to be a loading dose it's because the risk of a recurrence or propagation of a venus thrombolic event is highest in that first 3 weeks so the reason why we use 15 BD in that first 3 weeks is because of that risk being higher of a recurrence or propagation but in this setting they're already on anti-coagulation so they're not particularly higher risk because it's not a new diagnosis so I would just do 20 a day if it's therapeutic and if they were on a prophylactic intensity then I would do 10mg a day and the same safety data in breastfeeding has not been shown with Apixaban so we can't use that so just Rivaroxaban. Apart from pharmacological treatments how effective is movement, compression stockings and those kind of things?

So all of the data for compression stockings has come from the non-pregnant population as per usual and there is some reasonable data for hospitalized patients that have a contraindication to anti-coagulation that the compression stockings work but they certainly shouldn't replace anti-coagulation in someone who would who is has no contraindication to anti-regulation because there is limited evidence that they will prevent VTE in this population so if we can use anticoagulation i.e.there's no major bleeding concerns then I would suggest that rather than the compression stockings.

Movement's always helpful for almost everything so I would encourage that anyway.

If you had someone who declined Clexane didn't want to use it would you still encourage them to do those non-pharmacological things so I think in those settings in people do decline often and I think that's fine as long as we've had a very clear discussion with them in what their risks are with declining and that we feel that it's in their best interest to be on the anticoagulant so that their choice to decline it and in those settings yes I would encourage stockings and early mobilization if possible but our role is not to say "you must have this", obviously our role is just to say this is what I would recommend and these are the reasons why I recommend it.

You mentioned earlier the RCOG risk assessment tool are there any other risk assessment tools we should be aware of?

There's a huge number of risk assessment tools. There's the Queensland Health guideline, there's a Swedish guideline which actually performs quite well when it's reviewed,

there's the ASH (American Society of hematology guideline), there's the ACOG guideline also American,

there's numerous guidelines I think it's just in your own best interest to pick one and follow it because again these are all based on expert recommendations and the way that they come about is that we just take a whole database of women and we see what risk factors they had and see how many of those people with those risk factors got a PE or a DVT and actually we know that women and cases are much more nuanced than that so if you have pre-term birth was that pre-term birth with infection, was that pre-term birth with preclampsia, was that pre-term birth with immobilization so the cases are much more nuance than that so that's why our algorithms may not perform as adequately as we would like but we just for our own benefit we just have to pick an algorithm and go with it and I go with RCOG.

How frequently should women be having a risk assessment?

I think if anything major changes so I would say most hospital admissions I think unless as a contraindication I would say most women should have anticoagulation while they're in hospital and if they have an acute illness so acute infection, inflammatory bowel disease flare, flare of asthma 

they should be re-evaluated at those times and treatment offered if that is deemed necessary so most cases of an acute illness they should have some anti-coagulation.

Obviously pregnant women are going to go into labor and have a baby or they're going to have a cesarian section and there's always blood loss with that. How do we manage the timing of Clexane around that?

So I guess depends on the dose of the Clexane so if any woman is on anything higher than prophylactic dose Clexane so intermediate or therapeutic intensity Clexane they need to have 24 hours off their anticoagulation prior to birth and prior to neuraxial aesthesia. Obviously the birth can be unpredictable but if we are having a pl we would ideally have a planned birth with 24 hours off prior to the induction and then and then they have their baby and then in our case we usually do about 6 hours of pro 6 hours postpartum we would do prophylactic dose clexane and then about 12 hours postpartum we would do make that up to therapeutic dose.

Everyone has quite different ways of doing that but that's my personal recommendation so anyone with therapeutic anti-regulation should have a planned birth with their anticoagulation ceased 24 hours prior so that's critical from that point of view and if they have a birth before that we just have to call hematology and for advice and obstetric medicine and then in the settings of prophylactic anticoagulation the rules or recommendations are slightly less clear so I really just have a frank discussion with the woman. So they need to have 12 hours off anti-regulation for neuraxial anesthesia.

You mean epidural, spinal ...

Yes which is epidural or spinal anesthetic. So epidural if for pain relief during birth spinal anesthetic for pain relief during cesarian section and they need to have 12-hour break between their last dose and that procedure. Some women have a very strong desire to have whatever cost have neuraxial anesthesia epidural or spinal and they will not take any chance that won't be offered and so in those women I would suggest an induced birth with 12 hours break before the induction. In other women are just so dead set against an induction and all they want is to have a spontaneous birth in those women I just say stop your Clexane as soon as the early signs of labor and then come in earlyish so we can assess you or the obstericians and midwives can assess you and then we can plan whether they can take that dose or not.

So for prophylactic I would say planned birth is not mandatory or not very strongly recommended but for therapeutic antic regulation it's very strongly recommended.

Turning to contraception Caroline, what's the best for those who've had hormone related clots before?

So I think just someone having just a hormonally related clot it's not always just linked to the hormone medication for example the combined oral contraceptive pill often they're on the pill and had long distance travel or on the pill and um had a minor surgery or on a pill with a bit of immobility and so it's difficult to place the exact weight on the combined pill. Nevertheless uh there is certainly evidence that continuing the combined pill increases their risk long-term of recurrence so for my personal practice I would recommend

while on anti-coagulation and there's recent evidence to support this whereas before we were just doing it based on guidelines and expert opinion that if while someone's on anticoagulation they can have any mode of contraception but when the anticoagulation is going to be stopped either at 3 to 6 months then I would recommend progesterone only contraception's such as mini pill which is less effective or a marina or Implanon. So basically if they're on anticoagulation

probably the that's protecting them against a hormonal Associated clot whereas if they're not on anticoagulation I would recommend avoiding combined oral contraceptive pill.

Caroline, any particular advice for people who are trying to conceive particularly in the setting of an inherited thrombophilia?

I think what we get asked a lot as hematologists and obstetric physicians is whether or not people who are having suffering from recurrent miscarriages or having IVF difficulties with IVF would benefit from prophylactic in intensity anticoagulation and there's almost no data to support that so in in the setting of antiphospholipid syndrome there's no data that that results in implantation failure and using Clexane in that syndrome does not improve implantation rates so that's one no to Clexane in that setting although aspirin in those cases should be started preconception. In the setting of people who have recurrent miscarriages with an inherited thrombophilia the ALIFE 2 trial which was presented last year showed no benefit with prophylactic anticoagulation to prevent 
recurrent miscarriage in inherited thrombophilia so there's almost no benefit for prophylactic anticoagulation in trying to conceive only to prevent thrombosis during the pregnancy and postpartum.

Caroline thank you so much for coming in and sharing your knowledge with us today. Before you go though we want to introduce you to a little segment we call The Checkup. So we want to know more about you Caroline as Professional, Medical Professional and as a person so Maggie's going to ask you five quick questions. You ready? Do you listen to podcasts and if so what are your favorites? Yes I listen to podcasts. I like Hamish and Andy and and I also listen to some parenting podcasts. Good Inside is the parenting one that I love.

Who do you admire? Oh many, many people. I am lucky enough to work in two different departments so  
in terms of a professional people person that I admire I definitely admire both my directors in both my departments so Dr Lori and Dr Gutta and then outside that space  unfortunately she passed away a few years ago but Claire McLintock was a trail blazing obstetric hematologist who sadly passed away from breast cancer but she was an absolute inspiration.

If you had a wish from a genie to grant you one wish today what would you wish for? That my children and husband and I remain as healthy as we are.

Do you have any pets and if you do tell me about them and if you don't what would be your dream pet?

I don't have pets because I can't be bothered but my daughter would really love one and so I would like a dog because that's what she would like.

Do you have a go-to karaoke song? No, I don't have a single but I have a lot that I would dance to on the dance floor so like Whitney Houston Want to Dance with Somebody, Uptown Funk, anything Taylor Swift. Yeah I'll be there from the beginning to the end of the any dance floor.

Caroline thanks again so much for joining us on sMater. For our listeners at home or in the car or having a well deserved break between patients thanks for tuning in. See you next time on sMater.