title: Screening for deep venous thrombosis in asymptomatic postoperative orthopedic patients using color Doppler sonography: analysis of prevalence and risk factors.
abstract: OBJECTIVE
  The purpose of our study was to assess the prevalence and risk factors for sonographically detectable lower extremity deep venous thrombosis (DVT) in asymptomatic patients following major orthopedic surgery.
  
  
  METHODS
  We performed color Doppler sonography of the lower extremities in 474 asymptomatic patients following major hip or knee surgery. We determined the prevalence of lower extremity DVT and used stepwise logistic regression to identify factors predictive of DVT. All patients received routine prophylactic measures.
  
  
  RESULTS
  The prevalence of DVT was 7%. Laterality of surgery, age, and gender were all independent predictors of DVT (p < or = .01): the odds of having DVT were 20 times higher in the leg that was operated upon than in the leg that was not; the odds of DVT rose by a factor of 1.5 per decade of life; and the odds of DVT were 3.4 times greater in men than in women. DVT was more common in patients who had received general rather than epidural anesthesia, with borderline significance (p = .06). The length of anesthesia and the joint involved (hip or knee) were not predictive of DVT (p > .10).
  
  
  CONCLUSIONS
  Despite prophylaxis, DVT is a relatively common postoperative complication in patients who undergo major orthopedic procedures. Routine screening for DVT is warranted in asymptomatic patients who have undergone hip or knee surgery, and color Doppler sonography, despite its limitations, offers a reasonably accurate noninvasive method for screening these patients. Subsets of patients who are at particular risk include the elderly, male patients, and patients who have undergone general anesthesia. The low prevalence of DVT in limbs not operated upon suggests that routine screening may be limited to evaluating the affected limbs only, thus helping to minimize the cost of screening.
authors.affiliation: Department of Diagnostic Radiology and Nuclear Medicine, Stanford University Medical Center, CA 94305, USA.
authors.forename: H C
authors.initials: HC
authors.lastname: Davidson
authors.forename: D
authors.initials: D
authors.lastname: Mazzu
authors.forename: B F
authors.initials: BF
authors.lastname: Gage
authors.forename: R B
authors.initials: RB
authors.lastname: Jeffrey
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000767:Anesthesia, Epidural / Q000009:adverse effects; D000768:Anesthesia, General / Q000009:adverse effects; D005260:Female; D006621:Hip Joint / Q000601:surgery*; D006801:Humans; D007719:Knee Joint / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011183:Postoperative Complications / Q000000981:diagnostic imaging*; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors; D013924:Thrombophlebitis / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000209:etiology; D018615:Ultrasonography, Doppler, Color