Deep vein thrombosis

Deep vein thrombosis (DVT) is a condition where a blood clot (thrombus) forms, usually in the lower limbs (Kearon and Akl, 2014). It has an incidence of around 1 in 1000 annually and risk increases after the age of 40, as well as being associated with additional risk factors both transient and ongoing which are discussed in more detail in the aetiology section below. This paper will focus on lower limb DVT but guidance on other thrombotic events in other sites is available at the following link:

https://onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2141.2012.09249.x

A deep vein thrombosis (DVT) is where a blood clot or thrombus, from the Greek for lump or clot, forms or is present within a vein. It is usually within the lower limbs but can be found in upper arms or within more unusual sites in the body (Stone et al, 2017). If this clot breaks loose and travels through the bloodstream it is termed a thromboembolism.

The common signs and symptoms of a DVT include:

• Swelling of calf and/or thigh
• Pain and stiffness of affected limb
• Redness of affected limb
• Pitting oedema
• Increased skin temperature
• Erythema
• Tenderness
• Mild fever
• Swollen veins that are hard to the touch (Stubbs et al, 2018).

However, around half of people diagnosed with DVT will display little or no symptoms at all (Zang et al, 2019).

Many ideas around the aetiology of DVT look at Virchow’s triad which describes three factors being involved, namely:

• Alteration in the blood-clotting mechanism
• Alteration in the anatomical structure of the lining of a blood vessel
• Alteration in blood flow (Mehta et al, 2020).

Anything that prevents or reduces blood from flowing or clotting properly will increase the risk of DVT. Injury to a vein, particularly those associated with a surgical procedure, or changes to blood viscosity from dehydration, loss of blood flow or acute reduction in usual activity will all contribute toward formation of a DVT.

Hospital admission is known to increase the risk of DVT and pulmonary embolism (Lester et al, 2013), though appropriate risk assessment and prophylaxis prescribing will reduce the incidence (Sweetland et al, 2009; Khanna et al, 2014).

Medications such as hormone replacement therapy or the combined oral contraceptive pill will increase thrombosis risk.

Lifestyle factors such

A physical examination and review of general medical history is the first step to exclude other causes (National Institute for Health and care Excellence (NICE), 2020). If DVT is suspected then the 2 level Wells score (Table 1) should be used, with a score reflecting whether a DVT is likely or unlikely (Dybowska et al, 2015). If there is likely to be a delay in obtaining imaging then therapeutic anticoagulation, following guidance in the treatment section, should be initiated until a scan has been performed.

Treatment for a newly diagnosed DVT is with therapeutic anticoagulation to prevent the clot from embolising and travelling to the lungs and to prevent other clots from forming. Anticoagulation suppresses blood clot formation and propagation and should be taken for a minimum of three months, at which point a review should be carried out looking at the need for long term treatment dependent upon what provoking factors contributed to the DVT formation (Kearon and Akl, 2014).

Advice should be given to elevate the affected leg whenever immobile to reduce risk of swelling.

Simple analgesia may be required, paracetamol or codeine, but it is best to avoid non-steroidal anti-inflammatory medication as this may increase risk of bleeding.

Treatment options should be discussed as part of a shared decision process taking into account patient blood results.

Consider the use of compression hosiery to reduce the risk of post-thrombotic syndrome. This is a

Therapeutic anticoagulation treatment will offer a choice of a direct oral anticoagulant (DOAC), low molecular weight heparin (LMWH) or a vitamin K antagonist usually warfarin dependent upon patient preference, presenting symptoms and risks of side effects or contra-indications associated with each medication (Table 2).