The role of popliteal vein incompetence in the diagnosis of saphenous-popliteal reflux using continuous wave Doppler

Abstract

Introduction: Continuous wave Doppler (CWD) has good discriminatory power at the groin in the assessment of saphenous femoral junction (SFJ); however, it is not as accurate as duplex ultrasound scanning (DUS) in the popliteal fossa for assessment of saphenous popliteal junction (SPJ) in patients with primary short saphenous vein incompetence. Aim: The aim of this study was to compare the findings of CWD with those of DUS at the SPJ and assess the role of popliteal vein incompetence in the accuracy of CWD. Method: Prospective study of consecutive patients presenting to a vein clinic requiring a duplex scan of their SPJ. Each patient was examined by one surgeon using CWD and by one radiologist using DUS. Each observer was unaware of the other's findings. Additional information on the competence of the popliteal vein on DUS was also recorded. Results: Some 171 limbs in 128 patients with varicose veins were studied. One hundred and sixteen limbs had reflux at SPJ on CWD whilst 55 did not. Their mean age was 54 (range 18-85). Female to male ratio was 3:1. Spearman's rank correlation between CWD and DUS has 0.49 (p=0.0001). CWD has a sensitivity of 92% and specificity of 53% (PPV=62%, NPV=89%, accuracy=70%). Twenty-nine limbs had an incompetent popliteal vein (IPV). Of those, 12 limbs also had incompetence on CWD and competence on DUS at the SPJ, which represent 28% of the total number of limbs with these findings (n=43). Conclusion: CWD is sensitive in detecting incompetence at SPJ, though its specificity is low. In this study 17% (n=29) of all patients had incompetence of popliteal vein. Up to 25% (n=12) of patients with SPJ incompetence on CWD (Doppler +) and competence on DUS (duplex -) had incompetence of the underlying popliteal vein, which may explain the low specificity. The presence of SPJ incompetence on CWD should be confirmed on DUS prior to surgery.