The effect of varying tourniquet applications on the flow pattern of lower extremity radionuclide venography.

Radionuclide venography (RNV) is an accepted, reliable, and simple method for detecting thrombi of the deep venous system of the lower extremity. No universal agreement, however, has been established regarding specific techniques for tourniquet applications. In fact, present data reflect a general consensus that tourniquet use and location other than above the ankles has no appreciable or recognizable effect on study outcome. A prospective study was performed on 20 consecutive patients referred for RNV with the clinical impression of deep venous thrombosis (DVT). Each patient was studied initially with tourniquets above the knee and ankle, then with tourniquets above the ankle only, and finally without tourniquets. On the basis of standard criteria for DVT, 8 out of 20 patients were positive for DVT when the study was performed with tourniquets only above the ankle. Four of the eight positive studies became negative, however, when additional tourniquets were placed above the knees (20% false-positive rate). It is concluded that the routine application of additional tourniquets above the knees would eliminate a significant number of false-positive studies and should be part of an established routine protocol.