Objectives: The aim was to assess more accurately the net flow of the lower limb perforating veins (PVs).
Material and methods: This was an observational prospective study. Two hundred and twenty one limbs with chronic venous disease (C1-6EpAs,pPr) of 193 patients underwent a duplex ultrasound (DUS). All identified PVs were scanned also by means of quality Doppler profile (QDP) multigate analysis in order to determine their net inward and outward flow direction. A comparison between the traditional pulsed wave Doppler analysis and QDP was performed to detect potential discrepancy between the traditional definition of PV incompetence and a net outward flow.
Results: The DUS investigation identified 774 PVs. Only 7.7% of the PVs showed an outward flow lasting more than 500 ms. Among the PVs showing a longer than 500 ms outward flow, QDP assessment revealed net outward flow in only 84% of the PVs along the thigh and in 28.6% along the lower leg. Among the PVs showing a shorter than 500 ms outward flow, QDP assessment reported a net outward flow in 2.4% of the PVs along the thigh and in 47.3% of those along the lower leg. The sensitivity of an outward flow lasting more than 500 ms in detecting an actual net outward flow was 13.9% (9-20.1%). The specificity of an outward flow lasting less than 500 ms in detecting a net inward flow was 96.4% (93.2-98.3%).
Conclusions: A lack of overlap exists between the finding of a PV outward flow lasting more than 500 ms and the net outward flow of the same vessel. The traditional definition of PV incompetence is challenged by the reported data and further investigations are required to identify a gold standard assessment.
Keywords: Chronic venous disease; Net flow; Perforating vein.
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