Dependencies of vein diameters and venous valve function on patient positioning during duplex ultrasound examination.

Background: Duplex ultrasound assessment with the patient standing is standard for diagnosing chronic venous insufficiency (CVI). However, assessments are often performed with patients in tilted or supine positions due to age or physical limitations. This study aimed to evaluate the influence of the patient's positioning on venous diameters and venous valve function. Patients and Methods: Monocentric, prospective cohort study in 30 patients with CVI of the great saphenous vein (GSV). 18 contralateral limbs without GSV insufficiency were defined as the control group. With duplex ultrasound, we measured GSV diameters at different anatomic points. Moreover, we analyzed the occurrence of venous reflux (>0.5s) with the patient in a lying position (0°), on the tilting table in 30° and 70° positions, and with the patient standing (90°). Results: A linear relationship was found between patient inclination and diameters in varicose GSVs. Average diameters in limbs with CVI increased from lying to standing by 39-42%, while average diameters in healthy GSVs increased by 20-23%. In ≥97% of the patients, pathological venous reflux findings observed in the standing position were also detected in the 70° tilted position, with no statistically significant differences between these two positions. Conclusions: For duplex ultrasound examination of the GSV in cases of suspected CVI, it can be recommended to position the patient on a table tilted at 70°. This position provides results comparable to those obtained in the standing position while enhancing patient safety and examiner comfort.