title: D-dimers as a screening test for venous thromboembolism in pregnancy: is it of any use?
abstract: In non-pregnant women, D-dimers are used successfully to aid diagnosis 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 pregnancy 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 screening test for suspected PE in pregnancy and to determine if a negative D-dimer level could exclude the diagnosis 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 test for suspected PE in pregnancy 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 diagnosis of PE in pregnancy. However, this study suggests that D-dimer testing in pregnancy has a high negative likelihood ratio and should not be used. Larger prospective observational studies are required to collaborate the findings from this study.
authors.affiliation: Department of Obstetrics and Gynaecology, North Middlesex University Hospital, London, UK.
authors.forename: M
authors.initials: M
authors.lastname: Damodaram
authors.forename: M
authors.initials: M
authors.lastname: Kaladindi
authors.forename: J
authors.initials: J
authors.lastname: Luckit
authors.forename: W
authors.initials: W
authors.lastname: Yoong
mesh_terms: D015331:Cohort Studies; D005188:False Negative Reactions; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis*; D006801:Humans; D011247:Pregnancy; D011250:Pregnancy Complications, Hematologic / Q000097:blood / Q000175:diagnosis*; D011296:Prenatal Diagnosis; D011655:Pulmonary Embolism / Q000097:blood / Q000175:diagnosis*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D005338:Fibrin Fibrinogen Degradation Products; C036309:fibrin fragment D