biology

Ultrasonography of chronic venous insufficiency of the legs

Ultrasonography of chronic venous insufficiency of the legs is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Ultrasonography of chronic venous insufficiency of the legs rather than just read about it. In short: Ultrasonography of suspected or previously confirmed chronic venous insufficiency of leg veins is a risk-free, non-invasive procedure. It gives information about the anatomy, physiology and pathology of mainly superficial veins.

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Reference excerpt

Ultrasonography of suspected or previously confirmed chronic venous insufficiency of leg veins is a risk-free, non-invasive procedure. It gives information about the anatomy, physiology and pathology of mainly superficial veins. As with heart ultrasound (echocardiography) studies, venous ultrasonography requires an understanding of hemodynamics in order to give useful examination reports. In chronic venous insufficiency, sonographic examination is of most benefit; in confirming varicose disease, making an assessment of the hemodynamics, and charting the progression of the disease and its response to treatment. It has become the reference standard for examining the condition and hemodynamics of the lower limb veins. Particular veins of the deep venous system (DVS), and the superficial venous system (SVS) are looked at. The great saphenous vein (GSV), and the small saphenous vein (SSV) are superficial veins which drain into respectively, the common femoral vein and the popliteal vein. These veins are deep veins. Perforator veins drain superficial veins into the deep veins. Three anatomic compartments are described (as networks), (N1) containing the deep veins, (N2) containing the perforator veins, and (N3) containing the superficial veins, known as the saphenous compartment. This compartmentalisation makes it easier for the examiner to systematize and map. The GSV can be located in the saphenous compartment where together with the Giacomini vein and the accessory saphenous vein (ASV) an image resembling an eye, known as the 'eye sign' can be seen. The ASV which is often responsible for varicose veins, can be located at the 'alignment sign', where it is seen to align with the femoral vessels. On ultrasound at the saphenofemoral junction in the groin, the common femoral vein (CFV) with the GSV and the common femoral artery (CFA) create an image called the Mickey Mouse sign. The CFV represents the head, and the CFA and GSV represent the ears. The examination report will include details of the deep and the superficial vein systems, and their mapping. The mapping is drawn on paper and then drawn on the patient before surgery. The use of ultrasonography in a medical application was first used in the late 1940s in the United States. This use was soon followed in other countries with further research and development being carried out. The first report on Doppler ultrasound as a diagnostic tool for vascular disease was published in 1967–1968. Rapid advances since then in electronics, have greatly improved ultrasound transmission tomography.

Medical uses Ultrasonography of chronic venous insufficiency of the legs allows the examiner to evaluate the gross anatomy of the venous networks as well as the blood flow direction, which is crucial in determining vein pathology. It has become the reference standard used in the assessment of the condition and hemodynamics of the veins of the lower limbs. The normal physiological blood flow is antegrade, flowing from the periphery towards the heart, so evidence of an opposite, retrograde flow might indicate a pathology. The presence of a reflux is likewise of note; a reflux, when not isolated in a vein (as simply retrograde), means that the blood flow is bi-directional where once the flow had been only antegrade.

Risks No contraindications are known for this examination. Ultrasonography does not involve the use of ionizing radiation, and the procedure is harmless and can be safely used on anybody of any age. A 1998 World Health Organization report supports this.

Preparation No preparation is normally necessary for this examination, but if a complementary study of abdominal veins is also required, the patient will be asked to fast for 12 hours beforehand. The sensitivity and specificity measurements are around 90%.

Equipment

The ultrasound equipment must be sufficiently high-quality to give a correct image-processing result, which can then provide invaluable information, mainly at the superficial level. It must be able to provide both color and Doppler imaging, technologies that developed alongside the development of ultrasound. Doppler measurements which trace the echoes of the generated soundwaves received by the probe, enable the direction and velocity of the blood flow to be depicted. The overlay of color onto the Doppler information lets these images be seen more clearly. The choice of a probe will depend on the depth needed to be studied. For example, the superficial venous system (SVS) can be very well examined using a high-frequency probe of 12 MHz. For patients who have thick adipose tissue, a probe of 7.5 MHz will be required. Deep veins require probes of around 6 MHz, while the abdominal vessels are better studied with probes of between 4 and 6 MHz. In summary, three probes are needed together with a top level scanner. Also, the proper use of the scanner calls for a high level of expertise, so the examiner must be well qualified and experienced in order to give effective results. In contrast to arterial ultrasonography, the wall of the vein is not relevant and importance is given to the hemodynamic conclusions that the examiner can obtain in order to provide a valuable report. (Hemodynamics is the study of blood flow and of the laws that govern the circulation of blood in the blood vessels.) It follows that the examiner's knowledge of venous hemodynamics is crucial, which can be a real barrier to a radiologist, untrained in this field, who might wish to carry out these examinations. Specialized training in venous ultrasonography is not undertaken in some countries, which undermines best practice, mainly when varicose veins need to be examined.

Mechanism

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Illustrations

Worked examples

Example 1 — a first encounter with Ultrasonography of chronic venous insufficiency of the legs

Start with the simplest possible case. Write down what Ultrasonography of chronic venous insufficiency of the legs claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Ultrasonography of chronic venous insufficiency of the legs before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Ultrasonography of chronic venous insufficiency of the legs ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Ultrasonography of chronic venous insufficiency of the legs

In research: Ultrasonography of chronic venous insufficiency of the legs appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Ultrasonography of chronic venous insufficiency of the legs in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Ultrasonography of chronic venous insufficiency of the legs is common in secondary-school and first-year university syllabi. It links to neighbouring topics Diagnostic medical imaging, Diseases of veins, lymphatic vessels and lymph nodes, Medical ultrasonography, so understanding it makes those chapters shorter.
In everyday life: Look for Ultrasonography of chronic venous insufficiency of the legs outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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Frequently asked questions

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