Exam Strategy: The Two Scenarios
Scenario A: Suspected DVT
Your goal is to establish the likelihood of DVT using physical signs and to rule out differentials like cellulitis or a ruptured Baker’s cyst.
Scenario B: Confirmed DVT
Your goal is to assess the extent of the clot (does it extend to the thigh?) and, crucially, to look for Virchow’s Triad causes (malignancy, stasis, etc.) and complications (pulmonary embolism signs).
Entry & Wash
Enter the room, sanitise your hands visibly, and approach the patient.
Introduction & Consent
- Candidate: “Good morning. My name is Dr. [Name]. I am one of the exam doctors. I have been asked to examine your legs today. Is that okay?”
- Patient: “Yes, doctor.”
- Candidate: “This will involve me looking at your legs, feeling them for swelling or tenderness, and taking some measurements. It shouldn’t be painful, but if you are already in pain, please let me know and I will be very gentle.”
Positioning & Exposure
Action: Ideally, the patient should be standing for the inspection of veins, but for a standard DVT exam, they are usually supine (lying flat) or semi-recumbent. You must expose both legs entirely.
- Candidate: “Could you please remove your trousers/skirt so I can see both legs from the groin down? You may keep your underwear on.”
- Action: Ensure the legs are fully exposed. Cover the patient’s torso and groin area with a sheet to maintain dignity.
Stand at the foot of the bed. Do not rush to touch the legs yet.
Systemic Signs (The “Why”)
Verbalization: “On general inspection, I am looking for risk factors for DVT.”
- Malignancy: specific signs of cachexia (weight loss) or pallor (anaemia).
- Stasis: Is the patient in a cast? Are they obese? Do they appear bedbound?
- Respiratory Distress: “I am checking the respiratory rate and looking for cyanosis, which might suggest a pulmonary embolism (PE).”
Local Inspection of the Legs
Compare the left leg with the right leg.
- Candidate: “I am inspecting the legs for asymmetry, swelling, redness, or skin changes.”
- Swelling: Look for loss of the normal anatomical bony landmarks (like the malleoli) on the affected side.
- Colour: Look for erythema (redness) suggesting infection/inflammation, or cyanosis (blue/purple) suggesting severe venous obstruction.
- Veins: Look for distended superficial veins. In DVT, the deep system is blocked, so blood shunts to the superficial veins, making them prominent.
Important: Ask about pain before you touch. “Which leg is the sore one? Show me exactly where it hurts.” Start with the normal leg first.
Temperature
- Action: Use the dorsum (back) of your hand. Run your hand down the shin of the normal leg, then the affected leg.
- Candidate: “I am assessing the temperature. The left calf feels warmer than the right, which suggests inflammation.”
Tenderness & Texture
- Action: Gently palpate the calf muscles. Do not prod; use the pads of your fingers or the flat of your hand.
- Candidate: “I am feeling for tenderness and muscle induration (hardening).”
- Vein Palpation: Run your finger lightly over the course of the long saphenous vein (medial thigh/calf). If you feel a “cord-like” hard lump, it suggests superficial thrombophlebitis.
Pitting Oedema
- Action: Press firmly with your thumb over the medial malleolus and the shin for 5-10 seconds.
- Observation: If an indentation remains, pitting oedema is present. Check how high the oedema extends (to the knee? to the thigh?).
Warning: Homan’s Sign
Do not perform Homan’s Sign aggressively.
Homan’s sign involves forcibly dorsiflexing the foot to elicit calf pain. It is: 1. Unreliable: Low sensitivity and specificity. 2. Dangerous: Theoretically, it can dislodge a clot and cause a Pulmonary Embolism.
Candidate Verbalization: “I am aware of Homan’s sign, but I will not perform it as it is unreliable and potentially unsafe. I will rely on palpation and measurement.”
Subjective swelling can be misleading. You must measure.
Calf Circumference
- Action: Use a tape measure. Measure 10cm below the tibial tuberosity (the bony lump below the knee cap) on both legs.
- Candidate: “I am measuring the calf circumference at a fixed point, 10cm below the tibial tuberosity, on both legs to compare.”
- Significance: A difference of >3cm is clinically significant and is a point on the Wells Score.
A swollen, painful calf is not always a DVT. You must demonstrate you are thinking broadly.
Ruptured Baker’s Cyst
- Action: Palpate the popliteal fossa (behind the knee).
- Candidate: “I am palpating for a Baker’s cyst. I am also looking for crescent-shaped bruising around the malleoli (Crescent Sign), which indicates a ruptured cyst.”
Cellulitis
- Action: Look for a portal of entry (cut, insect bite, fungal infection between toes). Check the inguinal lymph nodes.
- Candidate: “I am checking between the toes for a portal of entry and palpating the groin for tender lymphadenopathy, which would point towards cellulitis.”
Conclude the Exam
Action: Cover the patient’s legs. “Thank you, that completes the examination. You can cover up now.” Wash your hands.
Presentation
Turn to the examiner and present your findings systematically.
“On examination of this patient, there is unilateral swelling of the left calf, which is 3.5cm larger than the right when measured. The calf is warm and tender to palpation, and there is pitting oedema to the mid-shin. Superficial veins are distended. There are no signs of cellulitis or Baker’s cyst. These findings are highly suggestive of a Deep Vein Thrombosis.”
The Wells Score
To sound authoritative, mention the Wells Score for DVT probability.
| Clinical Feature |
Score |
| Active Cancer |
+1 |
| Paralysis, paresis, or recent plaster immobilisation |
+1 |
| Recently bedridden >3 days or major surgery <4 weeks |
+1 |
| Localized tenderness along deep venous system |
+1 |
| Entire leg swollen |
+1 |
| Calf swelling >3cm (compared to asymptomatic side) |
+1 |
| Pitting edema (confined to symptomatic leg) |
+1 |
| Collateral superficial veins (non-varicose) |
+1 |
| Alternative diagnosis as likely or greater than DVT |
-2 |
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