Gestation-specific D-dimer reference ranges: a cross-sectional study.
OBJECTIVE
To establish a gestation-specific reference range for D-dimer in healthy pregnant women with a singleton pregnancy using the Auto-Dimer assay.


METHODS
Cross-sectional study


METHODS
Cork University Maternity Hospital, Ireland.


METHODS
Healthy pregnant women attending for routine antenatal care.


METHODS
Simultaneous-quantile regression was performed to construct a median, 5th percentile, and 95th percentile, model of normal pregnancy D-dimer concentration versus gestational week, ranging from week 6 to 42. Additionally, pair-wise Mann-Whitney U-tests were performed to compare distributions of D-dimer concentrations for each of the four discrete gestational sampling windows with the distribution of D-dimer concentrations 48 hours postpartum.


METHODS
D-dimer concentrations (ng/ml) during normal gestation (approximately week 6 to week 42).


RESULTS
Seven hundred and sixty healthy pregnant women were investigated between gestational age week 5 and 48 hours postpartum. There was a clear steady increase in median D-dimer concentrations over the complete gestational period. Additionally, the 95th centile estimates for all gestational time-points were above the accepted non-pregnancy normal cut-off concentration (224 ng/ml). The results of the Mann-Whitney U-tests suggested that the long-term postnatal return to normal D-dimer concentrations begins in the immediate postpartum period.


CONCLUSIONS
We found that there is a continuous increase in D-dimer concentrations across all gestations. This research is potentially beneficial to future diagnosis of venous thromboembolism (VTE) in pregnancy using the new recommended 95th centile potential cut-offs. Possible further investigation involves an observational study comparing D-dimer concentrations in women with proven DVT with those that don't, generating likelihood ratios.
INFANT centre, Department of Obstetrics and Gynaecology, University College Cork, Cork University Maternity Hospital, Cork, Ireland; Department of Obstetrics and Gynaecology, University College Cork, Cork University Maternity Hospital, Cork, Ireland.
N
N
Murphy
D I
DI
Broadhurst
A S
AS
Khashan
O
O
Gilligan
L C
LC
Kenny
K
K
O'Donoghue
D000328:Adult; D001780:Blood Coagulation Tests; D003430:Cross-Sectional Studies; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis*; D005865:Gestational Age; D006771:Hospitals, Maternity; D006801:Humans; D007494:Ireland / Q000453:epidemiology; D011247:Pregnancy; D011249:Pregnancy Complications, Cardiovascular / Q000453:epidemiology / Q000517:prevention & control*; D011261:Pregnancy Trimester, First / Q000097:blood; D011262:Pregnancy Trimester, Second / Q000097:blood; D011263:Pregnancy Trimester, Third / Q000097:blood; D011295:Prenatal Care; D012016:Reference Values; D054556:Venous Thromboembolism / Q000453:epidemiology / Q000517:prevention & control*; D016387:Women's Health
D005338:Fibrin Fibrinogen Degradation Products; C036309:fibrin fragment D
D-dimer; pregnancy; reference range; venous thromboembolism