Because hydrostatic pressure in the lower extremity increases peripherally, veins are equipped with increasing number of valves in the dependent regions of the leg. Valves come in a thicker reinforced form or a thin transparent form and usually feature two cusps. Venous valves act as mechanical gates allowing blood to flow centrally, but preventing flow from coursing peripherally In a normal lower extremity vein, venous competence is maintained by venous valves. The tilt table has two principal advantages: I strongly recommend a good‐quality, hard, narrow tilt‐table with hydraulic tilt and up/down movements. Which of the above setups the sonographer employs largely depends on the equipment available in the laboratory.
The leg under examination should be relaxed, slightly flexed at the knee and externally rotated The patient can be positioned for scanning in a variety of ways: standing on an elevated platform, combination of standing and sitting, recumbent position or lying on a tilt‐table in reverse‐Tredelenburg position at ≥ 30° or ≥ 60° incline. If the specialist suspects pelvic venous incompetence on the basis of patient's history and clinical examination, the patient should also be fasted for 6–8 hours in order to limit overlying bowel gas and peristalsis so that ovarian veins and internal iliac veins can also be examined. If possible, patients with minor varicose veins or cosmetic concerns should be scheduled in the later parts of the day The examination should be performed with the patient in a reverse Trendelenburg position or upright so that hydrostatic pressure in the veins is at its peak to aid venous distension. The patient should be instructed not to wear stockings on the day of the examination, the patient should arrive warm if possible and the examination room and gel should also be comfortably warm.
VENOUS DUPLEX FULL
The best examination of lower extremity veins is achieved when the veins are under full distension. The sonographer should answer the following questions: In clinical practice, the sonographer usually directly reports to the specialist who is will be treating the patient.
Any of these operators will henceforth be referred to as “sonographers”. The operator is usually a vascular sonographer, but it could also be a general sonographer with advanced vascular experience or a vascular surgeon, phlebologist, radiologist or interventionalist with sufficient duplex ultrasound expertise to carry out the examination The individual who performs the diagnostic duplex scan should have specific training in venous hemodynamics, the basics of clinical assessment, high level of training in vascular duplex ultrasound and should have completed a minimum of 250–400 supervised CVI examinations Duplex ultrasound scan is generally the only imaging test in these patients. As with other duplex examinations, the information which is sought on the duplex scan is predominantly dictated by what the specialist needs to know in order to treat the patient.
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