Venous thromboembolism (VTE) is the medical term for a blood clot that forms in a vein. It covers two related conditions: a deep vein thrombosis (DVT), where a clot forms in a deep vein — usually in the calf or thigh — and a pulmonary embolism (PE), where part of that clot breaks off and travels to the lungs. A PE can be serious, which is why preventing VTE is taken seriously around any surgical procedure.

Any operation, and the period of reduced mobility that follows it, increases the background risk of a clot forming. That risk is different for every patient, so before your surgery you will be asked a set of questions covering four areas: your personal details and the type of surgery planned, your past medical history, any regular medication, and your family history. This is standard practice for anyone undergoing surgery in the UK and is not specific to any one condition or operation.

The first area covers factors related to you and to the surgery itself. You will typically be asked about:

• Age (over 60) — the background risk of VTE rises gradually with age, and is factored into most standard risk-assessment tools.
• Obesity — a higher body mass index is an established, independent risk factor for VTE, partly through reduced mobility and partly through effects on blood flow and clotting.
• Smoking — smoking affects blood vessel walls and clotting factors, and is taken into account alongside your other risk factors.

The type and length of surgery, how mobile you are expected to be afterwards, and whether you are having a general or regional anaesthetic are also part of this assessment, since all of these affect your individual risk.

The second area covers your past medical history. This includes:

• Clotting disorders — an inherited or acquired tendency to clot more easily (thrombophilia), such as Factor V Leiden or antiphospholipid syndrome. If you or a doctor have previously identified one of these, please tell your surgical team.
• Previous clots — a personal history of a DVT or PE is one of the strongest predictors of a future clot, so this is always asked about specifically.
• Cancer — active cancer, or cancer treatment within the last six months, increases VTE risk and is factored into your prevention plan.

Other relevant conditions include inflammatory bowel disease, significant varicose veins, and recent hospital admission or immobility, so it is worth mentioning anything you think may be relevant even if it is not asked about directly.

The third area covers your current medication:

• OCP / HRT — the combined oral contraceptive pill and hormone replacement therapy both increase VTE risk slightly. Depending on the surgery, you may be advised to temporarily stop these beforehand — but this decision should always be made with your surgical team or GP, not on your own.
• Blood thinners — if you are already taking an anticoagulant (such as warfarin, a DOAC like apixaban or rivaroxaban) or an antiplatelet medication (such as aspirin or clopidogrel), your team needs to know so that your medication can be managed safely around the time of surgery.

Please bring a current list of all your medications, including over-the-counter and herbal supplements, to your pre-operative assessment.

The fourth area is your family history:

• Clots — a first-degree relative (parent, sibling or child) who has had an unprovoked DVT or PE, particularly at a young age, can point towards an inherited clotting tendency running in the family.

If this applies to you, it is helpful to mention which relative was affected and, if known, at what age — this can sometimes prompt further discussion about testing before surgery.

Once your answers to the four areas above have been reviewed, your risk of VTE is weighed against your individual risk of bleeding, and a prevention plan is agreed for your specific operation. This usually combines some or all of the following, in line with UK guidance on VTE prevention:

Mechanical measures

• Compression stockings (TEDs), where appropriate for the type of surgery and your circulation
• Intermittent pneumatic compression or foot pumps during and after surgery
• Early mobilisation as soon as it is safe to do so, and staying well hydrated

Medical (pharmacological) measures

• An injectable blood thinner (low molecular weight heparin), for a period determined by the type of surgery and your individual risk factors
• For some hindfoot, ankle or lower-limb procedures with reduced weight-bearing, a longer course of prophylaxis may be recommended

The right combination is always individualised — a patient with several risk factors having major surgery will usually need more protection than a younger, fit patient having a short procedure. Your team will explain the specific plan recommended for you and why.

It is worth knowing what to look out for after you go home, particularly in the weeks following surgery when mobility is often reduced.

Possible signs of a DVT (usually in the calf or thigh)

• Swelling in one leg, more than the other
• Pain or tenderness, often worse on standing or walking
• Redness or warmth over the affected area

Possible signs of a PE — seek urgent medical attention

• Sudden shortness of breath
• Chest pain, especially if it is worse when you breathe in
• A rapid heartbeat, feeling faint, or coughing up blood

Mr Matthew Welck is a Consultant Orthopaedic Foot & Ankle Surgeon at the Royal National Orthopaedic Hospital (RNOH), Stanmore, and treats NHS and private patients across London and North London. Every patient under his care undergoes an individualised VTE risk assessment before surgery, as part of routine pre-operative care.

Patients choosing Mr Welck benefit from:

• Subspecialist fellowship training in foot and ankle surgery
• A structured, individualised approach to VTE risk assessment and prevention for every surgical patient
• Treatment of NHS and private patients across London and North London, including RNOH Stanmore
• A multidisciplinary team, including pre-operative assessment nurses and anaesthetists, involved in your care around the time of surgery

If you have a question about your individual risk of blood clots ahead of planned foot or ankle surgery with Mr Welck, or would like to arrange a consultation, please get in touch.

To arrange a consultation with Mr Matthew Welck:

• Telephone: 07547 395 270
• Email/contact form: matthewwelck.com/contact
• NHS referrals: via your GP to RNOH Stanmore
• Private appointments: London and North London locations

This page is for information only. It does not replace personalised medical advice. Always consult a qualified specialist for diagnosis and treatment, and never stop or start any medication without first speaking to your doctor or surgical team.