Technique Rules Out DVTs in Pregnant Women, Eliminates Unnecessary Anticoagulation Meds

Serial compression ultrasonographic testing in conjunction with Doppler imaging can reliably rule out blood clots in the legs of women who are pregnant, according to new study findings.
   
This technique currently is recommended to determine the presence of deep vein thrombosis (DVT) in all women, but its efficacy in pregnant women specifically had not been validated previously. Although certain anticoagulation drugs are considered safe for use during pregnancy, their use in women in whom a blood clot has been incorrectly diagnosed can result in unnecessary risks both during and after pregnancy, such as thrombocytopenia, hemorrhage, and excessive bleeding.
   
To evaluate the safety of withholding anticoagulation drugs upon a normal finding on serial compression ultrasound and Doppler imaging of the iliac vein, researchers gathered data on 221 women with symptoms of DVT over an 8-year period. If the initial result was normal, serial testing on 2 occasions over the following 7 days was performed. Women whose findings were normal were monitored for at least 3 months for the development of symptomatic DVT or pulmonary embolism.
   
Of 221 women who presented with symptoms of DVT, initial compression ultrasonography and Doppler imaging of the iliac vein identified 16 (7.2%) cases of DVT. There were no cases of DVT identified on serial testing. One patient with normal findings on serial testing had a diagnosis of pulmonary embolism 7 weeks after the initial assessment. All women in whom DVT was diagnosed were treated with anticoagulation therapy.
   
Including the case of pulmonary embolism, the overall prevalence of DVT was 17 (7.7%) of 221 patients. Of these 17 cases of DVT, 11 involved the iliofemoral veins alone and 2 were isolated iliac DVTs. The sensitivity of serial compression ultrasonography with Doppler imaging was 94.1%, and the negative predictive value was 99.5%.
   
Given these findings, the study authors concluded that this technique can reliably exclude clinically important DVTs. In addition, anticoagulation drugs can be safely withheld in patients with negative findings. Because all cases of DVT were identified during the initial assessment, the authors also questioned whether serial testing over a 7-day period is necessary. Additional studies are needed to determine the clinical value of serial testing.

Pertinent Points:
- Compression ultrasonographic testing with Doppler imaging has high sensitivity (94.1%) and high negative predictive value (99.5%) for identifying deep vein thrombosis in symptomatic women who are pregnant.
- Anticoagulation drugs can safely be withheld in women with normal findings on ultrasonographic testing with Doppler imaging of the iliac vein.
 

References:

1. Chan WS, Spencer FA, Lee AY, et al. Safety of withholding anticoagulation in pregnant women with suspected deep vein thrombosis following negative serial compression ultrasound and iliac vein imaging. CMAJ. January 14, 2013. [Epub ahead of print]