How to properly examine the veins of the lower limbs: lying, sitting or standing?

Abstract
The article is a discussion of the advantages of a patient’s position during an ultrasound examination of the lower-limb venous system. The presented material is intended to objectively assess the advantages of this or that position of an examined patient in order to obtain necessary information about the state of the veins of the lower limbs from the position of doctors who have years of experience in diagnostics and treatment of acute and chronic diseases of the lower-limb venous system. The material of the article is primarily designed for doctors who, in addition to the ability to use an ultrasound scanner to some extent, know about venous hemodynamics and can afford to think outside the generally accepted concepts and clinical recommendations.The characteristics of the state of the lower-limb venous system at vertical and horizontal position of the patient are given. Schemes of venous pressure distribution in the system of the inferior vena cava in the horizontal and vertical position of the patient are presented. Methods of manual compression of the muscular mass and straining at different patient positions are described.The vertical position of the patient (or sitting position) is the most reliable way to identify the peculiarities of anatomical structure and pathological changes of the subcutaneous vein walls, which may be of great importance for planning and carrying out subsequent invasive manipulations, but there is a question about the expediency of making linear measurements in this position, if the invasive intervention is carried out while lying down. Carrying out compression ultrasound, assessment of hemodynamic parameters of venous blood flow, including the use of samples with straining and manual compression of muscle masses of the limb, it is much more convenient to perform in the lying position.