Surgery — Peripheral Vascular Disease and Leg Ulcers, NMC MBBS licence examination syllabus (Nepal Medical Council).
Peripheral Vascular Disease and Leg Ulcers
Putting a compression bandage on the wrong ulcer can cost the patient their leg. Telling them apart takes a minute.
Leg ulcers are common, chronic, and frequently managed by whoever sees the patient rather than by a specialist. They also carry one of the clearest examples in medicine of a treatment that is correct for one condition and destructive in another that looks similar.
Three ulcers, three mechanisms
Nearly every leg ulcer is venous, arterial, neuropathic, or a combination — and the features separate them reliably.
Venous ulcers are the commonest. They sit above the ankle, usually on the medial side, are shallow with sloping edges, and the surrounding skin shows the changes of long-standing venous hypertension — brown staining, oedema, and thickened skin. The patient's legs ache and feel heavy, and elevation helps.
Arterial ulcers occur where perfusion is worst: the toes, the heel, and pressure points. They are deep, with a sharply demarcated "punched out" edge, and they are painful — characteristically worse when the leg is elevated, because gravity was helping. The foot is cold, pulses are diminished or absent, and the skin is hairless and slow to refill.
Neuropathic ulcers sit under pressure points on the sole, typically beneath the metatarsal heads, surrounded by callus. The defining feature is that they are painless.
One question does most of the work: does it hurt, and does elevation make it better or worse? A venous ulcer aches and improves with elevation. An arterial ulcer hurts and worsens with elevation. A neuropathic ulcer does not hurt at all. That single line of history separates the three before you have touched the leg.
The mistake that costs a leg
Compression is the treatment for venous ulceration, and it is effective. It opposes the venous hypertension that produced the ulcer, and without it venous ulcers do not reliably heal.
On a limb with arterial disease it is catastrophic. The leg already has inadequate arterial inflow; external compression reduces it further, and can convert a chronic ulcer into necrosis and limb loss.
💡 So the rule is absolute: assess the arterial supply before applying compression, every time. Feel the pulses, look at the foot, and where there is any doubt, have the arterial supply formally assessed. This matters most in the patients who look most obviously venous — an elderly arteriopath can have venous skin changes and arterial disease simultaneously, and the ulcer that appears venous may be both.
No pressure index values are quoted in this chapter. Thresholds differ between sources, and the measurement is unreliable in calcified vessels — which occurs particularly in diabetes and chronic kidney disease, exactly the patients in whom a falsely reassuring number would do the most damage.
How far has the arterial disease gone?
Arterial insufficiency progresses through a recognisable sequence, and where the patient sits on it determines the urgency.
Intermittent claudication. Pain in the muscle on walking, relieved by rest, and reproducible at roughly the same distance. Supply meets demand at rest but not on exertion. Managed by risk factor modification and exercise.
Rest pain. Supply no longer meets even resting demand. The characteristic feature is that it is worse lying flat and relieved by hanging the leg out of bed — because gravity assists perfusion.
Tissue loss — ulceration or gangrene.
Rest pain and tissue loss together define critical limb ischaemia, which needs urgent vascular referral: without restored blood flow, the limb will be lost. And a practical detail worth carrying — a patient who says they have been sleeping in a chair may be describing rest pain, not insomnia. Ask why they moved out of bed.
The acutely ischaemic limb
This is a surgical emergency measured in hours. The features are conventionally remembered as six words beginning with P: pain, pallor, pulselessness, perishing cold, paraesthesia and paralysis.
The order matters more than the list. Paraesthesia and paralysis are late features — they mean nerve and muscle are already being damaged. A limb with sensory or motor loss is further along than one that is merely painful and pale, and needs faster action rather than more investigation.
Embolus or thrombosis? A sudden onset in a patient with atrial fibrillation, with a normal contralateral leg and no history of claudication, suggests an embolus. A more gradual onset in a patient with known peripheral arterial disease and claudication in both legs suggests thrombosis on existing disease. The distinction affects the operation, which is why the vascular team ask.
Refer immediately. Muscle tolerates ischaemia for only a few hours, and waiting for imaging to confirm what the examination already showed wastes the time in which the limb could be saved. A mottled limb that does not blanch on pressure is generally beyond salvage.
The diabetic foot
The diabetic foot deserves separate treatment because it combines three problems, and each conceals the others.
Neuropathy — the injury is never felt. A stone in the shoe, a tight sandal strap, a burn from a heater. Nothing hurts, so nothing prompts the patient to stop.
Ischaemia — so the injury cannot heal. Arterial disease in diabetes tends to be more distal and more diffuse, which also makes it harder to bypass.
Infection — which spreads with remarkably few signs. Deep infection and osteomyelitis can exist beneath a small, quiet-looking ulcer, and the usual inflammatory response may be muted.
Which produces the practical instruction: inspect the feet of every patient with diabetes, at every opportunity, including between the toes and under the heel. They will not complain, because they cannot feel it — so the absence of a report of foot trouble means nothing at all. This is one of the few examinations where finding nothing is genuinely reassuring and not performing it is genuinely negligent.
Varicose veins, briefly
Varicose veins are extremely common and mostly a cosmetic and symptomatic problem — aching, heaviness and swelling that worsen through the day and improve on elevation.
The features that make them a medical rather than cosmetic issue are the complications of the venous hypertension behind them: skin changes, ulceration, bleeding from a superficial varix, and superficial thrombophlebitis. A patient with varicose veins and skin changes is on the path to a venous ulcer, and treating them prevents one.
Putting it together
Does it hurt, and does elevation help or worsen it? That separates venous, arterial and neuropathic ulcers.
Never compress before assessing the arterial supply — the same treatment heals one ulcer and destroys another limb.
Claudication → rest pain → tissue loss. The last two together are critical limb ischaemia and need urgent referral.
Sleeping in a chair may be rest pain, not insomnia.
Paraesthesia and paralysis are late in the acutely ischaemic limb — refer before imaging.
Inspect every diabetic foot, because the patient cannot feel what is wrong with it.
No pressure index values, bandage pressures or time limits appear here: index thresholds are unreliable in calcified vessels, which is precisely the diabetic population most at risk. Use your local protocol and refer early.
Syllabus points
Venous, arterial and neuropathic ulcers
Does it hurt, and does elevation help?
Never compress before assessing arterial supply
Claudication, rest pain, tissue loss
Sleeping in a chair may be rest pain
The acutely ischaemic limb; late features
Embolus vs thrombosis
The diabetic foot — three problems at once
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