Deep Vein Thrombosis (DVT) OSCE Examination

1. Introduction
2. General Inspection
3. Closer Inspection of the Legs
4. Palpation of the Legs
5. Measuring Calf Circumference
6. Assessment of Oedema
7. Peripheral Pulses and Neurovascular Status
8. Differential Diagnosis of a Swollen Leg
9. Risk Factors and the Wells Score
10. Completing the Examination
11. Quiz

Wash your hands thoroughly and don personal protective equipment if appropriate.

Introduce yourself to the patient and ensure to mention your grade e.g. 3rd year medical student/junior doctor/consultant.

Confirm the patient’s details taking 3 points of identification usually; full name, date of birth and NHS/hospital number.

Obtain consent for the examination, ensuring to explain what the examination will entail.

Ask the patient if they are currently experiencing any pain, particularly in the legs, as a DVT is frequently tender and you should be gentle when palpating.

Position the patient lying on the bed at 45^o, and expose both legs fully from the groin to the toes so that the two limbs can be directly compared. Maintaining the patient’s dignity, only expose what is necessary.

Begin by standing at the end of the bed and observing the patient as a whole. Note whether they appear comfortable or in distress, and look for signs that may point towards an underlying cause or complication. Patients with a DVT may be in pain from the affected leg, and those who have developed a pulmonary embolism may appear breathless (tachypnoeic), distressed, or be receiving supplemental oxygen.

Look around the bedside for objects and clues that give context to the patient’s condition. Relevant findings include compression stockings, evidence of recent surgery, mobility aids suggesting reduced mobility, intravenous lines, and monitoring equipment such as a pulse oximeter or oxygen mask. Many of the risk factors for DVT relate to venous stasis (immobility), so signs of recent immobilisation – such as a plaster cast, a walking frame, or a recently operated limb – are particularly relevant.

Compare the two legs side by side. A DVT is typically unilateral, so an obvious difference in size, colour or swelling between the two legs is an important early observation. Bilateral symmetrical swelling is much more likely to reflect a systemic cause such as heart failure, renal failure or hypoalbuminaemia than a DVT.

Inspect both legs more closely, comparing the symptomatic leg against the asymptomatic side. Look specifically for the cardinal signs of a DVT:

• Swelling – unilateral swelling of the calf or whole leg is the most consistent sign of a DVT, caused by the thrombus obstructing venous return and increasing venous pressure distal to the clot. This raised pressure forces fluid out of the capillaries into the tissues.
• Erythema – the skin overlying the affected segment may appear red and inflamed because of the local inflammatory response to the thrombus.
• Dilated superficial veins – prominent, non-varicose superficial veins may develop as collateral channels when the deep veins are obstructed and blood is diverted into the superficial system.
• Varicose veins – tortuous, dilated superficial veins are a marker of venous insufficiency. They are not caused by an acute clot, but they signal abnormal venous function and are a recognised risk factor for a DVT, so note them when present.
• Skin changes – longstanding venous disease can cause hyperpigmentation (haemosiderin deposition), lipodermatosclerosis and venous ulceration, typically around the medial malleolus.

In severe, extensive proximal thrombosis, the leg can become markedly swollen and discoloured. A pale, swollen leg is termed phlegmasia alba dolens, while a tense, dusky, cyanotic leg – phlegmasia cerulea dolens – represents near-complete venous outflow obstruction and is a vascular emergency that threatens the limb.

Image - A deep vein thrombosis of the right leg, showing unilateral swelling, redness and a visible increase in size compared with the left leg

Creative commons source by James Heilman, MD [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)]

Also inspect for venous ulcers, which are a feature of chronic venous insufficiency and may coexist with, or follow, a previous DVT as part of post-thrombotic syndrome. Venous ulcers are usually shallow, have an irregular border and characteristically occur in the gaiter area around the medial malleolus.

Image - A venous leg ulcer. Venous ulcers reflect chronic venous insufficiency and may follow a previous DVT as part of the post-thrombotic syndrome

Creative commons source by Jonathan Moore [CC BY 3.0 (https://creativecommons.org/licenses/by/3.0)]

Before palpating, again confirm the patient is not in too much pain and warn them that you will be touching the leg, as a DVT is often tender.

Assess and compare the temperature of both legs using the backs of your fingers, working up the limb and feeling at several points so the two sides are compared at matching levels. An area that feels warmer than the contralateral leg supports the diagnosis, as the local inflammation around a thrombus increases blood flow and warmth to the overlying skin. Be aware that warmth is not specific to a DVT and is also seen in cellulitis, which is an important differential for a hot, red, swollen leg.

Palpate gently along the line of the deep veins for tenderness. Tenderness along the deep venous system – particularly in the calf, popliteal fossa and adductor canal – is one of the clinical features used to estimate the probability of a DVT, and reflects the inflammatory reaction provoked by the clot within the vein.

While in the popliteal fossa, feel for any discrete swelling behind the knee. A fluctuant lump here may be a Baker’s cyst, which can mimic a DVT – if it ruptures it produces sudden calf pain and swelling that is clinically very difficult to distinguish from a clot, and is a recognised reason for an inconclusive examination that warrants ultrasound.

While palpating, also feel along any prominent superficial veins. A vein that feels firm, hard or cord-like and is tender, with overlying redness and warmth, suggests superficial thrombophlebitis – clot within a superficial vein accompanied by inflammation. This is a distinct entity from a DVT, but the two can coexist and superficial thrombophlebitis of the long saphenous vein can extend into the deep system, so it should always be noted and the deep veins assessed carefully.

You may have heard of Homan’s sign, in which forced dorsiflexion of the foot reproduces pain in the calf. Although traditionally taught, this sign is unreliable – it is neither sensitive nor specific – and is now generally discouraged, partly because of a theoretical concern that it could dislodge a clot. It should not be relied upon to diagnose or exclude a DVT, and modern practice uses validated risk scoring and imaging instead.

Objective measurement of leg swelling is more reliable than visual estimation, so the calf circumference of both legs should be measured and compared. Using a tape measure, identify the tibial tuberosity on each leg and measure both calf circumferences 10 cm below the tibial tuberosity so that you are comparing the same point on each leg.

A symptomatic calf at least 3 cm larger than the asymptomatic side contributes one point to the two-level DVT Wells score. This includes a difference of exactly 3 cm and supports assessment of clinical probability; it does not diagnose a DVT. Measuring at a fixed point relative to a bony landmark gives a reproducible value that can be tracked over time, rather than relying on subjective ‘eyeballing’ of the legs.

Preview the Deep Vein Thrombosis (DVT) OSCE Examination quiz