title: Serial impedance plethysmography in pregnant patients with clinically suspected deep-vein thrombosis. Clinical validity of negative findings.
abstract: OBJECTIVE
  To determine the safety of withholding anticoagulant therapy in pregnant patients with clinically suspected deep-vein thrombosis who have negative results by serial impedance plethysmography.
  
  
  METHODS
  Prospective study evaluating prognosis by long-term follow-up to 3 months postpartum in all patients.
  
  
  METHODS
  University-affiliated community hospital and referral center.
  
  
  METHODS
  One hundred fifty-two consecutive pregnant patients referred with clinically suspected deep-vein thrombosis. All patients completed the study.
  
  
  METHODS
  Anticoagulant therapy was withheld in 139 patients negative by serial impedance plethysmography, and the patients were followed long term.
  
  
  RESULTS
  None of 139 patients (0%; 95% CI, 0% to 2.6%) had symptomatic pulmonary embolism or recurrent venous thrombosis.
  
  
  CONCLUSIONS
  The findings establish the safety of withholding anticoagulant therapy in pregnant patients who have negative results after serial impedance plethysmography. Sufficient patients were entered to provide narrow confidence intervals on the outcomes observed in patients with negative findings by impedance plethysmography. These findings are similar to those seen after venography in symptomatic patients. These data extend the role of non-invasive testing in patients with clinically suspected deep-vein thrombosis to the pregnant symptomatic patient.
authors.affiliation: Chedoke-McMaster Hospitals, Hamilton, Ontario, Canada.
authors.forename: R D
authors.initials: RD
authors.lastname: Hull
authors.forename: G E
authors.initials: GE
authors.lastname: Raskob
authors.forename: C J
authors.initials: CJ
authors.lastname: Carter
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007866:Leg / Q000098:blood supply; D010690:Phlebography; D010992:Plethysmography, Impedance / Q000379:methods*; D011247:Pregnancy; D011249:Pregnancy Complications, Cardiovascular; D011446:Prospective Studies; D013924:Thrombophlebitis / Q000175:diagnosis* / Q000000981:diagnostic imaging; D013997:Time Factors