In recent years, medicine has seen the spread of bedside ultrasonography beyond the traditional scope of practice employed by early emergency sonologists.1–4 Many of the new applications adopted by emergency sonologists have resulted from a clinical need to improve efficiency of patient care. One such application has been ultrasonography for the detection of deep venous thrombosis (DVT).5, 6 This typically refers to lower extremity DVT, although the frequency of upper extremity DVTs encountered appears to be increasing.7
Approximately 260,000 cases of lower extremity DVT are diagnosed each year in the United States.8 These, in turn, are thought to lead to as many as 50,000 deaths per year due to pulmonary embolism.8 To avoid the potentially fatal sequelae of DVT, physicians in the United States order almost 500,000 lower extremity duplex ultrasound examinations per year.9 Many vascular ultrasound laboratories find it difficult to maintain 24-hour coverage, 7 days per week, for emergency evaluation.10 This has resulted largely from lack of funding and trained personnel. Many hospitals now have an absence of vascular laboratory services during off-hours. The result is that the emergency or primary care physician is compelled to empirically treat and often admit patients who may have a DVT.
Overcrowding in emergency departments has stretched resources to the breaking point, resulting in delays in obtaining a host of services for emergency department patients. Moreover, even though extremity ultrasonography may be available at a facility, it may take hours to obtain a result, thus delaying the patient in the emergency department unnecessarily. Emergency physicians choosing to perform ultrasound examinations of the lower extremity themselves have been shown to decrease the time to patient disposition by over 2 hours.11
The high incidence and considerable morbidity and mortality resulting from DVT, coupled with the potential difficulty encountered in trying to diagnose it, has made this a disease of significant importance.12 The use of low-molecular-weight heparin makes it possible to send some patients home without obtaining a diagnostic study. The patient can then undergo an outpatient study the following day, which, if negative, would lead to termination of anticoagulation therapy.13, 14 However, there are some drawbacks to this strategy. Patients who are sent home require training in self-administration of low-molecular-weight heparin. This may be difficult to accomplish in a busy emergency department or outpatient setting. Furthermore, despite the relatively low incidence of bleeding with low-molecular-weight heparin, complications are occasionally encountered and can be severe. Another reality is that many primary care physicians still elect to admit their patients with actual or suspected DVT. Lastly, although rare, a fresh DVT can resolve rapidly with anticoagulation and it is possible that an ultrasound obtained 24 hour later may not demonstrate a DVT since it has already resolved—perhaps temporarily. This is a disservice to the patient who may not undergo a full evaluation for DVT or is at risk for recurrence.