Deep vein thrombosis: Increased risk in pregnancy

Clinical bottom line (level 4)

  1. Women during pregnancy and the puerperium were at increased risk for venous thromboembolism (NNF = 1700 for months)
Kierkegaard : Arch Obst Gynecol Scand 1983; 62: 239-243
Expires December 2003

The study

Retrospective cohort study with objective outcomes, not adjusted for confounding factors, not validated in an independent set of patients.

Setting: community hospital, Sweden, 1975-80

14869 patients (aged ?, 100% female) pregnancy to 4 weeks post-partum
Cases: patients (100% female, mean age ): proven venous thromboembolic disease
Controls: ?patients : women in same cohort without VTE


Outcomes studied:
  • deep vein thrombosis diagnosed by venography
  • pulmonary embolus diagnosed by CXR, ABG and lung scan

    • The evidence

    Patient expected event rate for deep vein thrombosis: 0.01%
    risk factor for
    deep vein thrombosis     		adjusted OR
    (95% CI)    		 NNH
    (95% CI)
    pregnancy to 4 weeks post-partum
    ( to )     		1350
    (833 to 3330)

    Patient expected event rate for pulmonary embolus: 0.01%
    risk factor for
    pulmonary embolus     		adjusted OR
    (95% CI)    		 NNH
    (95% CI)
    pregnancy to 4 weeks post-partum
    ( to )     		7690
    (-20000 to 3130)

    Comments

    1. Results are an underestimate, since DVT is impossible to exclude clinically

    Citation

    1. Kierkegaard A, : Incidence and diagnosis of DVT associated with pregnancy. Arch Obst Gynecol Scand 1983; 62: 239-243
    Contributor: Chris Ball and Bob Phillips, April 1997
    Reviewer:

    Clinical Question.
    Patient pregnant
    Intervention or Exposure prevalence
    Outcome DVT, PE, VTE, thromboembolism