Deep vein thrombosis: impedance plethysmography returned to normal within a year.

Clinical bottom line (level 4)

  1. In patients with a deep vein thrombosis, impedance plethysmography returned to normal in 95% of cases within one year (most within nine months).
Huisman et al: Archives of Internal Medicine 1988; 148: 681-683
Expires May 2003

The study

Prospective cohort study with unblinded, unobjective outcomes, not adjusted for confounding factors, not validated in an independent set of patients.

Setting: acute hospital, Holland

161 patients (aged range 18 to 95 years; mean 60, 65% male) venogram-proven proximal deep vein thrombosis
All patients were anticoagulated for three months.

95% followed for 12 months
Outcomes studied:
  • normal IPG at 3 months
  • normal IPG at 6 months
  • normal IPG at 9 months
  • normal IPG at 12 months

    • Patients had repeat impedance plethysmography (IPG) every three months.

    The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)
    normal IPG at 3 months 12 months 101/151 67%
    (59% to 74%)
    normal IPG at 6 months 12 months 126/148 85%
    (79% to 91%)
    normal IPG at 9 months 12 months 133/145 92%
    (87% to 96%)
    normal IPG at 12 months 12 months 139/146 95%
    (92% to 99%)

    • 7% of patients had a recurrent DVT.
    • Four patients still had abnormal IPG when a recurrence occurred. Two had uninterpretable venograms.

    Comments

    1. Are the results similar for ultrasound scanning?

    Citation

    1. Huisman MV, Buller HR, ten Cate JW: Impedance plethysmography in the diagnosis of recurrent deep-vein thrombosis. Archives of Internal Medicine 1988; 148: 681-683
    Contributor: Chris Ball and Clare Wotton, May 2000
    Reviewer:

    Clinical Question.
    Patient DVT
    Intervention or Exposure prevalence of normal IPG
    Outcome at three month intervals