Members Evidence Request - Supporting Clinical Practice

The Clinical Effectiveness Unit (CEU) provides an evidence-based enquiry service for FSRH members. The CEU will conduct a literature review and summarise the available evidence in relation to a particular medical condition and/or contraceptive method.

Recent Questions and Answers that have been submitted to the CEU can be seen below. Please note, the full answer includes references to more information and guidance.

The FSRH CEU has produced a quick guide on conducting systematic literature reviews to answer clinical questions (log in to access the guide). This brief and easy-to-use guide aims to support FSRH members to conduct a systematic literature search/review to answer clinical enquiries they may have. The process described in this guidance is adapted from the process used by the FSRH CEU when responding to enquiries made via the members evidence request service.

How to Submit a Members' Evidence Request

How do I get access to the Members' Evidence Request?

  • please log in to ‘My FSRH’ and
  • click on ‘Members' evidence request’ to search for questions or submit your own question.

This service is available to current FSRH members (Diplomates, Associates, Members, Fellows). 

I haven't set up a log in yet - what should I do?

If you are an FSRH member and have not yet created your ‘My FSRH’ account, please click the ‘Register’ button on the top right of this website and follow the steps to gain access to your account. Please use an email address that we will have contacted you on previously.

Once you have registered you will be able to access the full service and search the database as shown in the video. 


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Example Question One

A 21 year old patient using Rigevidon for 12 months had a stroke following knee surgery. We advise patients to stop using CHC 4 weeks prior to surgery because of the VTE risk. Could the CHC be implicated in the aetiology of the stroke in this patient as it also increases the risk of arterial thrombosis?


Many studies have demonstrated changes in haemostatic parameters associated with use of combined hormonal contraception (CHC); examples are referenced here. [1-7] However the relevance of specific haemostatic changes to thrombosis risk is unclear and the vast majority of studies do not consider changes in haemostatic parameters after stopping CHC. One small study (n=24), published in 1991 monitored changes in some haemostatic markers after stopping CHC.[8] The authors concluded that prothrombotic changes persist for several weeks after stopping CHC and postulated that these changes could “add to the known thromboembolic risks of major surgery”. They recommended that CHC should be stopped at least 4 weeks prior to surgery – by which time “fibrinogen concentration is low, antithrombin III concentration is high, and factor X concentration has nearly returned to control.”

Epidemiological studies demonstrate increased risk of thromboembolic events (both venous and arterial) associated with use of CHC (as referenced in the FSRH guideline, Combined Hormonal Contraception 2019) [9] but numbers of arterial thromboembolic events in CHC users remain small. The guideline states: “The absolute risk of arterial thromboembolism (ATE) in young women is very low but increases markedly with age through a woman’s reproductive years. Most studies indicate that current use of CHC is associated with increased risk of ischaemic stroke and myocardial infarction (MI) compared to non-use of CHC; risk appears to increase with increasing dose of estrogen in COC. The absolute risk of ATE remains extremely small for CHC users; a large Danish cohort study reported 2.1 thrombotic strokes and 1.0 MI per 10 000 woman-years of use of hormonal contraception (the majority of the cohort used COC).However, any increase in risk is important because the morbidity and mortality associated with ATE events are significant.” The guideline advises that “The risk of ATE among past-users of COC is similar to that for never-users.” but the available evidence does not allow “past use” to be defined in terms of length of time since stopping CHC.

Evidence relating specifically to perioperative risk of thromboembolism in women using CHC is limited and conflicting.[10] Risk of perioperative thrombosis associated with CHC use must also be weighed carefully against thrombotic risk associated with perioperative pregnancy that could result if effective contraception is stopped

The FSRH CEU concludes that the contribution of CHC use to risk of perioperative thromboembolic events (arterial and venous) has not been quantified; potential increased risk must be considered in the context of risk of thrombosis associated with unplanned perioperative pregnancy resulting from stopping CHC. The length of time for which increased thrombotic risk associated with CHC use persists after stopping CHC is not known. It is, however established practice to stop CHC at least 4 weeks prior to major surgery. The effect on thrombosis risk of prophylactic anticoagulation for women who have recently used or are currently using CHC at the time of surgery is not clear from the available evidence. The FSRH guideline Combined Hormonal Contraception 2019 [9] recommends that, because of the potential for CHC to further increase perioperative thrombosis risk, “Women should be advised to stop CHC and to switch to an alternative contraceptive method at least 4 weeks prior to planned major surgery or expected period of limited mobility.” It is important that effective alternative contraception is initiated when stopping CHC in this situation.

It is assumed from your question that the woman’s stroke was thrombotic. The available evidence indicates that use of CHC is not associated with increased risk of haemorrhagic stroke.[9]

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Example Question Two

I had a 35 year old patient attending, stopped smoking cigarettes 2 years ago. Now vaping only for 2 years. She is really happy using Microgynon and really does not want to change. I am aware of previous responses from 2016, that evidence was lacking, so to treat as per current UKMEC for smoking >35 years. Is there any new research/evidence on this now?


A March 2019 systematic review outlines the limits of the available evidence relating to cardiovascular outcomes with e-cigarette use.[1] While there are roughly a dozen studies looking at the effects of e-cigarette use on cardiovascular biomarkers (e.g., heart rate, blood pressure, platelet aggregation), additional research is required to determine the short- and long-term effects of e-cigarette use on the development and progression of

The review did identify one study that included myocardial infarction (MI) as an outcome measure. A 2018 study based on the U.S. National Health Interview Survey found e-cigarette use among daily users (n=776) was associated with an increased risk of MI (OR=1.79, 95% CI=1.20-2.66, p=0.004) while former and non-daily use was not significantly associated with an increased risk.[2]This study was limited by self-reporting and no data on when MI occurred relative to the start of e-cigarette use. This was the only study identified in the review that looked at a cardiovascular event as its outcome.

The conclusion of the systematic review, that more research is needed to fully understand the harms of e-cigarettes, is in line with the findings of the 2018 Public Health Consequences of E-Cigarettes published by the US National Academies of Sciences, Engineering, and Medicine’s Committee on the Review of the Health Effects of Electronic Nicotine Delivery Systems.[3] The publication states that, “no available evidence whether or not e-cigarette use is associated with clinical cardiovascular outcomes (coronary heart disease, stroke, and peripheral artery disease) and subclinical atherosclerosis (carotid intima media thickness and coronary artery calcification).”

This echoes a 2017 systematic review on the adverse health effects of e-cigarette use that determined there is inadequate evidence to reach a conclusion on whether e-cigarette use affects stroke risk.[4]

A 2019 study which also used data from the U.S. National Health Interview Survey found that compared with non-users, e-cigarette users had higher odds of MI (OR 1.558, 95% CI 1.447-1.678, p >0.0001), stroke (OR 1.297, 95% CI 1.201-1.400, P >0.0001) and circulatory problems (OR 1.436, 95% CI 1.251-1.648, P >0.0001).[5] As only the abstract has yet been published, it is not possible to determine strengths or limitations of this study.

This is still an emerging field with limited evidence and the cardiovascular risks associated with e-cigarette use remain unclear. The FSRH CEU cannot make any evidence-based recommendation as to how use of e-cigarettes affects cardiovascular risk in CHC users; however increased risk of arterial thrombotic events cannot be excluded.

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Example Question Three

Does FSRH still recommend the dorsogluteal injection site for Depo Provera?


Concerns have been raised about

  1. 1. Sciatic nerve injury resulting from dorsogluteal intramuscular (IM) injections
  2. 2. Dorsogluteal IM injections accidentally being given subcutaneously to women with high BMI

Sciatic nerve injury. The risk of significant nerve injury associated with any IM injection is very small (accurate data are lacking). There have been reports of sciatic nerve injury associated with dorsogluteal IM injection.[1] The dorsogluteal injection site is closer to neurovascular structures than the ventrogluteal site [2]; to reduce risk of sciatic nerve injury clinicians can administer IM DMPA at the ventrogluteal site if they have been trained to do so.[3] IM DMPA can also be given at the deltoid injection site (the volume is only 1ml) although axillary nerve injury is also possible.[1] Subcutaneous DMPA (Sayana Press®) is an alternative option to avoid risks associated with IM injection and has the advantage that women can self-administer. [3,4]

Accidental subcutaneous administration. The effectiveness of Depo Provera® given subcutaneously is unknown. One study suggested that a large number of injections that were intended to be given intramuscularly at the dorsogluteal site (and a smaller proportion at the ventrogluteal site) were administered subcutaneously in error.[5] The FSRH Guideline Overweight, Obesity and Contraception 2019 recommends that for women with obesity:-

If using intramuscular DMPA or norethisterone enanthate injectable, consider use of a longer-length needle or deltoid administration to ensure the muscle layer is reached.
Consider use of subcutaneous DMPA. [6]

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Please note: The advice given by the CEU should be considered as guidance only and is meant to be used alongside clinical judgement to guide clinical practice or policy. Questions that are a matter of clinical judgment and not evidence should be directed to local sexual and reproductive health leads.