Medicine — Venous Thromboembolism, NMC MBBS licence examination syllabus (Nepal Medical Council).
A clot in the leg and a clot in the lung are the same illness at two moments — and the second one kills patients who were walking around the day before.
Venous thromboembolism is common, frequently silent until it is dangerous, and largely preventable. It is also the topic where the examinable skill is a sequence of reasoning rather than a set of facts: decide how likely it is, and only then choose a test.
Deep vein thrombosis is the clot where it formed, usually in a leg: swollen, warm, tender, and characteristically on one side. That asymmetry does much of the diagnostic work — bilateral leg swelling is far more often heart, liver or kidney disease, where the mechanism is systemic rather than a blockage in one vein.
Pulmonary embolism is the same clot after it has broken loose and lodged in the lung: sudden breathlessness, pleuritic chest pain, sometimes collapse.
The point that changes practice: most patients with a pulmonary embolism have no leg symptoms at all. The clot has left the leg, and often was never large enough to be noticed there. A normal-looking leg is not reassurance — examining it is worth doing because a positive finding helps, but a negative one excludes nothing.Virchow's triad is usually recited and rarely used. Taken as three questions to ask a patient, it becomes a history rather than a list.
Stasis — has this blood stopped moving? Immobility, long travel, a plaster cast, paralysis, a long operation. This is the commonest contributor and the most preventable.
Vessel injury — has the wall been damaged? Surgery, trauma, a central line, or previous thrombosis in the same vein.
Hypercoagulability — does this blood clot too readily? Cancer, pregnancy and the weeks following it, oestrogen-containing medication, and inherited thrombophilia.
This is the part examiners test, because it is reasoning that transfers rather than a number to recall.
Assess clinical probability first, using a structured score, and do it before any result is available. A probability judged after seeing a test is not a probability; it is a rationalisation.
Where probability is low, a negative D-dimer is enough to exclude the diagnosis. The test is sensitive and not specific — it is very good at ruling out and poor at ruling in, because it rises in infection, cancer, pregnancy, recent surgery and simply with age.
Where probability is high, go straight to imaging. A negative D-dimer would not change your management, and that is precisely the reason not to order one.
Most pulmonary embolism is diagnosed and then treated. A minority presents with sustained low blood pressure or collapse, and that patient is in obstructive shock — the right ventricle is failing against a circulation that has suddenly been blocked. NMCMD01 covers the shock classification.
Signs of right heart strain support it: a raised jugular venous pressure, a loud second heart sound, and ECG changes of strain rather than ischaemia.
A large share of hospital-acquired thromboembolism is preventable, which is why risk assessment on admission is a standard expectation rather than a refinement. Admission is itself a risk factor: illness, immobility and often a procedure, arriving together.
Prophylaxis is a balance, not a default. Clotting risk is weighed against bleeding risk — active bleeding, a recent bleed into the brain, or a very low platelet count all change the calculation. Where drug prophylaxis is unsafe, mechanical methods and early mobilisation remain available and are not optional extras.
A woman returns from a long flight with a swollen, tender left calf. Unilateral swelling with a clear stasis risk factor. Assess probability, and let that decide between a D-dimer and going straight to imaging.
A man three days after major abdominal surgery becomes suddenly breathless with pleuritic pain. His legs look normal. Normal legs do not reduce the probability — most PE patients have none. Surgery supplies stasis and vessel injury together, so probability is high and imaging comes first.
A patient with suspected PE has a low probability score and a negative D-dimer. That combination excludes it. Further imaging exposes them to contrast and radiation for no gain.
A patient collapses with a low blood pressure, a raised jugular venous pressure and clear lungs. Consider massive pulmonary embolism as obstructive shock. Senior help immediately, and do not move them to a scanner unmonitored.
A normal leg and no pulmonary embolism. Unrelated. Most PE patients have no leg findings.
D-dimer as a diagnostic test. It excludes; it does not confirm. A raised D-dimer in an unwell patient usually means they are unwell.
Bilateral leg swelling and DVT. Bilateral points towards heart, liver or kidney disease. DVT is characteristically one-sided.
Prophylaxis as automatic. It is a judgement weighing clotting against bleeding, reassessed as the patient changes.
DVT and PE are one disease. Finding one means asking about the other.
Most PE patients have no leg symptoms.
Stasis, vessel injury, hypercoagulability — three questions, not a recitation.
Probability first, then choose the test. Low probability plus negative D-dimer excludes; high probability goes straight to imaging.
Do not order a test whose negative result you would ignore.
Hypotension with PE is obstructive shock — senior help, and do not transport unmonitored.
Assess prophylaxis on admission, balancing clotting against bleeding.
Create a free account to tick topics off, take notes as you read, watch the video lessons and get a day-by-day study plan built around your exam date.
Loading…