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D-dimers as a screening test for venous thromboembolism in pregnancy: is it of any use?

Damodaram, M.

D-dimers as a screening test for venous thromboembolism in pregnancy: is it of any use? - 2009

NMUH Staff Publications 29

<span style="font-size: 10pt;"><span style="line-height: 17.999801635742188px;">In non-pregnant women,&nbsp;</span><span class="highlight" style="line-height: 17.999801635742188px;">D-dimers</span><span style="line-height: 17.999801635742188px;">&nbsp;are used successfully to aid&nbsp;</span><span class="highlight" style="line-height: 17.999801635742188px;">diagnosis</span><span style="line-height: 17.999801635742188px;">&nbsp;of suspected pulmonary embolus (PE), as they have high sensitivity, moderate specificity and high negative predictive value. However, D-dimer levels are physiologically raised in&nbsp;</span><span class="highlight" style="line-height: 17.999801635742188px;">pregnancy</span><span style="line-height: 17.999801635742188px;">&nbsp;and thus overlap the values normally associated with PE. The aim of this retrospective study therefore was to investigate the use of D-dimer levels as a&nbsp;</span><span class="highlight" style="line-height: 17.999801635742188px;">screening</span><span style="line-height: 17.999801635742188px;">&nbsp;</span><span class="highlight" style="line-height: 17.999801635742188px;">test</span><span style="line-height: 17.999801635742188px;">&nbsp;for suspected PE in&nbsp;</span><span class="highlight" style="line-height: 17.999801635742188px;">pregnancy</span><span style="line-height: 17.999801635742188px;">&nbsp;and to determine if a negative D-dimer level could exclude the&nbsp;</span><span class="highlight" style="line-height: 17.999801635742188px;">diagnosis</span><span style="line-height: 17.999801635742188px;">&nbsp;in pregnant women. A total of 37 women suspected of PE had both ventilation perfusion (VQ) scans and D-dimer levels performed. Thirteen were reported as having a low probability of PE following VQ scan, while 24 were thought to have a moderate or high probability of PE. Women who had a low probability of PE following VQ scanning were found to have D-dimer levels ranging from 0.25-2.2 mg/l, while women who had a high probability of PE following scanning had D-dimer levels ranging from 0.31-1.74 mg/l. The sensitivity and specificity of D-dimer as a&nbsp;</span><span class="highlight" style="line-height: 17.999801635742188px;">test</span><span style="line-height: 17.999801635742188px;">&nbsp;for suspected PE in&nbsp;</span><span class="highlight" style="line-height: 17.999801635742188px;">pregnancy</span><span style="line-height: 17.999801635742188px;">&nbsp;was calculated to be 0.73 and 0.15 respectively, while the negative likelihood ratio was 1.8. Current guidelines advocate the use of a negative D-dimer result to exclude the&nbsp;</span><span class="highlight" style="line-height: 17.999801635742188px;">diagnosis</span><span style="line-height: 17.999801635742188px;">&nbsp;of PE in&nbsp;</span><span class="highlight" style="line-height: 17.999801635742188px;">pregnancy</span><span style="line-height: 17.999801635742188px;">. However, this study suggests that D-dimer testing in&nbsp;</span><span class="highlight" style="line-height: 17.999801635742188px;">pregnancy</span><span style="line-height: 17.999801635742188px;">&nbsp;has a high negative likelihood ratio and should not be used. Larger prospective observational studies are required to collaborate the findings from this study.</span></span>

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