PB0464 - D-dimer ratio to re-establish trimester-specific reference ranges of D-Dimer in pregnant women: a pooled study.

Background: The trimester-specific reference ranges of D-dimer established in previous studies differ greatly and were limited to use, due to poor standardization and harmonization of D-dimer assays. D-dimer ratio (DDR), the ratio of the D-dimer value to the upper limit of the normal range (ULN) for the current D-dimer assay, shows directly a proportional level of D-dimer elevation, and is independent of type of unit used.

Aims: The aim of this pooled-study was to re-establish a uniform trimester-specific reference range of D-dimer using DDR.

Methods: A searched strategy was performed to screen the studies on the reference range of D-Dimer during pregnancy published before July 4, 2023, in the databases of PubMed, Embase, Cochrane Library and Scopus. According to the inclusion and exclusion criteria, the literature was screened, and data were extracted. The DDR was calculated for the upper limit of the normal reference range of D-dimer in the first, second and third trimester for each study, and then the weighted mean of DDR was calculated.

Results: A total of 24 studies involved 28041 normal pregnant women aged between 16 to 50 years old were included in analysis (Table 1). More than 10 types of instruments and reagents were used in these studies. A pooled analysis including 17017 ,4836, and 11868 subjects in the first, second and third trimester, showed that the weighted mean of DDR was 2.12, 4.22, and 6.20, respectively.

Conclusion(s): The use of DDR to re-establish the trimester-specific reference range of D-dimer that may be applicable to all laboratories helps to improve the consistency of detection and reporting of D-Dimer in pregnant women.