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Outpatient delayed screening for patients with suspected deep vein thrombosis

      To the Editor
      Venous thromboembolism is estimated to affect approximately 2 million Americans per year and is a frequently encountered problem in the emergency department (ED) [
      • Anand S.S.
      • Wells P.S.
      • Hunt D.
      • et al.
      Does this patient have deep vein thrombosis?.
      ]. Although venography is the “gold standard” test for diagnosing deep vein thrombosis (DVT), it has been mostly replaced by noninvasive testing using ultrasound (US). In many areas of the United States and Canada, there is a shortage of technicians trained to perform these studies. As a result of this shortage, technicians will quit if they are repeatedly called in at night. This has caused some vascular laboratories to refuse doing scans at night. Because many patients present after normal business hours when no technician is available, emergency physicians are faced with either admitting all patients with suspected DVT, holding them all night in the ED, or allowing selected patients to be followed up as outpatients. It has been previously shown that patients with DVT can be safely treated as outpatients using low-molecular-weight heparins [
      • O'Shaughnessy D.F.
      • Tovey C.
      • Miller A.L.
      • et al.
      Outpatient management of deep vein thrombosis.
      ,
      • Schwarz T.
      • Schmidt B.
      • Hohlein U.
      • et al.
      Eligibility for home treatment of deep vein thrombosis: prospective study.
      ,
      • Dunn A.S.
      • Schechter C.
      • Gotlin A.
      • et al.
      Outpatient treatment of deep venous thrombosis in diverse inner-city patients.
      ]. Bauld and Kovacs [
      • Bauld D.L.
      • Kovacs M.J.
      Dalteparin in emergency patients to prevent admission prior to investigation for venous thromboembolism.
      ] proposed using low-molecular-weight heparin to avoid admission before US investigation in patients with suspected DVT.
      Starting in 1999, our hospital instituted a clinical guideline of delayed investigation of patients with suspected DVT who present after normal business hours. Patients were risk stratified using the scale proposed by Anand et al [
      • Anand S.S.
      • Wells P.S.
      • Hunt D.
      • et al.
      Does this patient have deep vein thrombosis?.
      ]. If the emergency physician felt that a patient was at high risk for DVT or complications, the patient was admitted for heparinization and screened with US in the morning. If a patient was not at high risk and immediate US was unavailable, the patient was given an injection of enoxaparin (1 mg/kg to a maximum of 150 mg/kg) and discharged to return in the morning for a US of the affected extremity. Before being given an injection of enoxaparin, a patient is supposed to have a platelet count measured. A low platelet count was a contraindication for the use of enoxaparin. Ultrasound was available from 9 am to 5 pm, 7 days a week including weekends and holidays.
      During 2001, a total of 101 patients had delayed outpatient screening US using this guideline. Of the 101 patients, 5 had DVT and 3 had superficial thrombophlebitis. There were no problems with bleeding complications identified from the chart review. In the 5 patients in whom DVT was diagnosed, based on a chart review of their admission, there were no pulmonary emboli. Although the protocol was well received by both emergency physicians and vascular US staff, there were problems with protocol violation. Thirty-nine patients did not have a screening complete blood count to exclude a low platelet count. Twenty-one patients did not receive enoxaparin, including one patient who was ultimately diagnosed with DVT. The reason given in the chart for not giving the enoxaparin was very low suspicion of DVT. There were 5 patients who did not have their scan performed within 12 hours as proscribed in the protocol. One of these patients did, in fact, have a DVT and was not scanned for 2 days.
      Although it is optimal to be able to screen all patients with suspected DVT during their emergency visit, it simply cannot be done in every institution. The use of this protocol may help alleviate ED overcrowding. This study did reveal problems with guideline compliance that must be addressed and corrected. Unfortunately, this study was limited by its small size, retrospective design, and use of an unproven protocol.
      In conclusion, we found that delayed outpatient screening for DVT in selected patients at lower to moderate risk functioned well in a large suburban hospital. We avoided unnecessary admissions and overuse of the US technician after hours. Further large prospective studies are needed to prove the safety of this approach.

      Acknowledgment

      The authors thank the staff of the Bethesda North Vascular Lab for their support.

      References

        • Anand S.S.
        • Wells P.S.
        • Hunt D.
        • et al.
        Does this patient have deep vein thrombosis?.
        JAMA. 1998; : 1094-1099
        • O'Shaughnessy D.F.
        • Tovey C.
        • Miller A.L.
        • et al.
        Outpatient management of deep vein thrombosis.
        J. Accid. Emerg. Med. 1998; : 292-293
        • Schwarz T.
        • Schmidt B.
        • Hohlein U.
        • et al.
        Eligibility for home treatment of deep vein thrombosis: prospective study.
        BMJ. 2001; : 1212-1213
        • Dunn A.S.
        • Schechter C.
        • Gotlin A.
        • et al.
        Outpatient treatment of deep venous thrombosis in diverse inner-city patients.
        Am. J. Med. 2001; : 458-462
        • Bauld D.L.
        • Kovacs M.J.
        Dalteparin in emergency patients to prevent admission prior to investigation for venous thromboembolism.
        Am. J. Emerg. Med. 1999; : 11-15