The last decade has witnessed a marked change in the attitude of physicians to the diagnosis of venous thrombosis. The early observation made by Haeger1 of the nonspecificity of clinical diagnosis has been confirmed repeatedly2-4 and it is no longer acceptable to make management decisions on clinical diagnosis alone. Venography, the diagnostic standard, is now safer and more reliable because of improved standards of technique and interpretation.5,6 Nevertheless, venography has limitations. It is invasive, it cannot be performed conveniently in an outpatient setting, and it requires the services of an experienced radiologist; even then, approximately 15% of venograms are technically inadequate. For these reasons, and the additional reason of the cost of unnecessary hospital admissions, there has been increasing interest in the development and application of noninvasive techniques that can be performed at the patient's bedside or in an emergency room. A number
See also p 681.