Why do both arteries and veins look at the legs when there is an ulcer?
Pain in the legs, swelling and changes in the skin of the legs can be of venous, arterial or mixed origin, and outwardly these conditions can be similar. A trophic ulcer on the leg is in most cases venous, but approximately every fifth patient also has significant damage to the arteries. This changes everything: with a venous ulcer, compression hosiery is the basis of treatment, and with concomitant arterial insufficiency, compression can lead to necrosis. Therefore, the study of both channels is not an expansion of volume, but a necessary safety measure.
The venous part of the study evaluates the patency of deep veins using compression tests, the consistency of the valves of the great and small saphenous veins and perforators with the determination of reflux during the Valsalva maneuver, and also identifies blood clots with a description of their extent and the nature of the apex - a floating thrombus is dangerous because of embolism and requires urgent measures. The result of this part is the basis for planning the treatment of varicose veins.
The arterial part shows atherosclerotic plaques and stenoses along the entire length from the iliac arteries to the arteries of the foot, evaluates the shape of the spectrum and calculates the ankle-brachial index. This is of particular importance in diabetes mellitus, where the arteries of the leg are predominantly affected, and classic intermittent claudication is often absent due to neuropathy - the condition is detected only instrumentally, often already at the ulcer stage.
What does duplex scanning show?
The method combines conventional ultrasound imaging of a vessel with analysis of the blood flow in it. The wall of the artery and vein, the thickness of the intima-media complex, atherosclerotic plaques with an assessment of their structure and the degree of narrowing of the lumen, blood clots, aneurysms, tortuosity and pathological anastomosis are visible.
Spectral analysis translates this into numbers: peak systolic velocity, end-diastolic velocity, resistance indices. They are used to calculate the percentage of stenosis - an indicator that determines whether conservative treatment is sufficient or intervention is required.
Functional tests
Some vascular pathology appears only during exercise. Compression tests detect thrombosis: a healthy vein is completely compressed by the sensor, a thrombosed one is not. The Valsalva maneuver shows the incompetence of the venous valves and reflux underlying varicose veins.
Positional tests are used when compression syndromes are suspected, when a vessel is compressed by muscles, ligaments or an additional rib in a certain position of the limb. At rest the picture is normal.
Advantages over other methods
Duplex scanning does not require contrast or radiation, so it can be repeated as often as necessary, including in cases of renal failure and allergies to iodine-containing drugs, where contrast angiography is contraindicated.
Operator-dependent method: the result depends significantly on the experience of the doctor and the quality of the device. Therefore, when making fundamental decisions, for example, before vascular surgery, the study is often repeated or supplemented with computed angiography.