Duplicated popliteal and superficial femoral veins: Incidence and potential significance

Background: Duplication of the popliteal and superficial femoral veins (PV, SFV) is a normal variant previously reported in up to 25% of limbs. Little clinical significance, however, has been attributed to this apparently com mon anomaly. The present study was designed to determine the incidence of d uplications in individuals presenting for venous incompetence studies, and whether their presence could, in theory, act as a predisposing factor to de ep venous thrombosis (DVT) formation. Methods: Duplex ultrasound examinations were performed in which venous dupl ications were actively searched for and recorded. The diameters of both lim bs of any duplicated system and the single vessel immediately distal to it were recorded. Using these measurements, the changes in total cross-section al area (CSA) associated with these anomalies were calculated. In addition, with the knowledge that the volume flow rate must remain constant, the vel ocity changes associated with such systems were calculated. Results: A total of 248 limbs from 177 patients was scanned. Duplications w ere found in 39 (15.7%) of these limbs. Of these, 30 limbs (77%) involved o nly the SFV, seven (18%) involved both the SFV and PV, and two (5%), involv ed only the PV. Short-segment SFV duplications were used to calculate the p ercentage change in total CSA and therefore blood now velocities. Of the 13 (33%) suitable for such calculations, and calculating for each individual duplicated system, a mean increase in the vessel's total CSA of 42%, which corresponded to a theoretical decrease in blood now velocity of 36%, was fo und. Conclusion: The present study confirms the significantly high incidence of duplications of the PV and SFV and mises the possibility of the potential f or DVT formation secondary to changes in flow velocities.