Test | Description | Finding | Sensitivity (%) | Specificity (%) | Positive predictive value (%) | Negative predictive value (%) |
---|---|---|---|---|---|---|
Tap test | With the patient standing, a hand is placed over the SFJ, and the LSV is tapped at the level of the knee with the other hand. | A palpable transmitted impulse denotes that the LSV is distended with blood. The SFJ is then tapped and the presence of a retrograde, palpably transmitted impulse at the knee indicates incompetence of valves between the SFJ and the LSV, with reflux in the proximal LSV. | 18 | 92 | 70 | 47 |
Cough test | With the patient standing, a finger is placed on the thigh over the SFJ. | A palpable thrill or impulse on coughing is indicative of an incompetent SFJ. | 59 | 67 | 64 | 38 |
Perthes test | With the patient standing, a tourniquet is applied below the knee. The patient is directed to complete 10 heel raises. | If the varicosities empty, the site of reflux is above the tourniquet. If the veins remain distended, the site of reflux is below the tourniquet. | 97 | 20 | 55 | 13 |
Trendelenburg test | With the patient in the supine position, the affected leg is elevated to 45 degrees to drain the varicosities. A tourniquet is applied just below the SFJ, and the patient is directed to stand. | Failure of the varicosities to fill indicates that the SFJ is the site of reflux. | 91 | 15 | 52 | 38 |