DVT is generally asymptomatic to patients and difficult to detect on physical examination.

Clinical signs, including Homans sign, palpable cords, and edema are notoriously unreliable for detecting DVT; therefore, screening tests such as contrast venography, Doppler ultrasound, or magnetic resonance venography are often used to establish whether DVT exists.

With the development of accurate noninvasive screening methods, routine screening for DVT after arthroplasty has been performed at some centers;29 however, a recent large, prospective, randomized trial comparing hospital discharge ultrasound with "sham" ultrasound showed no advantage to screening.30

Ascending Contrast Venography

    Fig. 3
    Click image to enlarge and to view caption.

  • Ascending contrast venography is the gold standard in detecting DVT.
  • It is usually performed by means of cannulation of a dorsal vein in the foot.
  • Advantages:
    • Acute diagnostic sensitivity
    • Direct visualization of DVT
  • Disadvantages:
    • Local discomfort at the injection site
    • Possible hypersensitivity reaction to the contrast agent
    • Iatrogenic thrombosis secondary to contrast injection
    • Fig. 4
      Click image to enlarge and to view caption.

    • Expensive and technically demanding
      • The cost efficacy of venography as a routine surveillance tool for DVT has yet to be definitively proven.

Color Doppler Ultrasound

  • Color doppler ultrasound is widely used in detecting DVT.
  • It combines high-resolution tissue imaging, display of flow information, and conventional Doppler analysis.
  • It is a noninvasive, relatively inexpensive technique.
  • The sensitivity of color Doppler ultrasound in detecting DVT remains controversial:
    • Extremely operator-dependent
      • Numerous studies have reported that a considerable learning curve exists with ultrasound.31
    • Appears to be more sensitive in the detection of proximal DVT than in calf DVT
      • A meta-analysis showed that the sensitivity of color Doppler ultrasound ranged from 38% to 100% in detecting silent, postoperative proximal DVT and 10% to 88% for calf DVT.31

Magnetic Resonance Venography

  • Magnetic resonance venography can detect DVT based on flow characteristics as demonstrated by intravenous gadolinium contrast.
  • It may be useful in detecting thrombi in the pelvic veins, which are difficult to evaluate using ultrasound and standard ascending venography.
  • One study evaluating DVT after THA showed a 39% incidence of pelvic thromboses detected by magnetic resonance venography that were not observed with either ascending venography or Doppler ultrasound.12
  • High cost and limited availability currently limit the use of magnetic resonance venography.
  • Magnetic resonance venography may emerge as a more common modality for diagnosing DVT in the future.