The diagnostic approaches to the problem of occlusive arterial disease have been reviewed. The history and physical examination are most useful in establishing the diagnosis, localizing the most proximal level of the arterial involvement, and categorizing the patient's stage of disease. Functional evaluation of limb blood pressures and flow velocity at rest and after exercise provide useful data for estimating the degree of the arterial involvement, and this information can be used as the baseline for evaluating the effects of therapy.
There are a variety of noninvasive testing procedures which can be used to establish the diagnosis of acute venous thrombosis with a high degree of certainty. For prospective screening of patients at risk, only 125I-labelled fibrinogen is of value, but does have a false positive rate of 21%. Its greatest problem is that it must be given prior to the event and, furthermore, it is not accurate in the upper thigh or the region of the iliac veins. Doppler ultrasound, plethysmography and phleborheography are accurate methods of detecting thrombi which involve the major veins of the limb from the level of the tibial veins below the knee to the level of the iliac veins in the abdomen. If properly performed, the sensitivity and specificity should exceed 90% in experienced laboratories. Contrast phlebography remains the best method of demonstrating venous thrombosis but does have limitations with regard to costs, pain to the patient and the production of thrombosis in a small percentage of patients. Furthermore, if the injections are done at the foot level, at least 18% will have inadequate visualization of the iliac veins, a critically important venous segment. It use must be restricted to those situations in which the noninvasive tests are equivocal or the information is absolutely essential for a therapeutic decision.
Doppler ultrasound is the preferred screening test in asymptomatic patients with high risk for venous thrombosis. Radiographic phlebography leads to definitive diagnosis in most instances. Radionuclide angiography using 99mTc MAA with delayed images to detect particle entrapment in venous blood clots can be used when radiographic phlebography is contraindicated or impractical. To detect active thrombosis in patients with past venous disease, the serial fibrinogen uptake test is the method of choice. This method is also used to monitor the efficacy of anticoagulation therapy and to detect propagating thrombosis in patients failing to respond to anticoagulation, hopefully before massive lethal pulmonary embolism occurs. Radionuclide methods are contraindicated in pregnant women and children where non invasive methods are preferred. No completely satisfactory test exists for detection of hypogastric vein thrombosis. Among the methods currently being evaluated in the laboratory the ultrasound B-scan imaging, 99mTc MAA uptake test and 99mTc mAA venous scan offer the best possibilities for successful clinical application.
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