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An evaluation of Doppler ultrasound and photoplethysmography in the investigation of venous insufficiency.

Non-invasive methods of venous assessment have been developed to improve diagnostic accuracy in the assessment of venous insufficiency. Of these, continuous wave Doppler (CWD) ultrasound and photoplethysmography are the cheapest and most simple to perform. In this study duplex scanning was used to test the accuracy of these two methods. One hundred and thirty-six patients attending the venous outpatient clinic at Middlesex Hospital, London were examined by all three techniques and a diagnosis was reached using each technique. The technicians performing the examinations were unaware of the diagnoses reached by the other methods. Continuous wave Doppler ultrasound was found to be most accurate in the diagnosis of long saphenous incompetence (sensitivity 73%, specificity 85%). Due to the variability of venous anatomy at the popliteal fossa and the 'blindness' of the technique, it was inaccurate in the diagnosis of short saphenous incompetence (sensitivity 33%) and deep vein reflux (sensitivity 48%). Photoplethysmography was found to be most accurate in the diagnosis of deep vein reflux (sensitivity 79%, specificity 70%) but was inaccurate in identification of the site of superficial vein reflux. Inaccuracies may be attributed to the presence of incompetent perforating veins and variation in arterial inflow.