The use of viscoelastic hemostatic tests in pregnancy and puerperium: review of the current evidence ‐ communication from the Women's Health SSC of the ISTH

Abstract

| INTRODUC TI ONRecent years have shown increasing interest in the use of thromboelastography (TEG) (Haemonetics, Braintree, MA) and thromboelastometry (ROTEM; Munich, Germany). These are established point-of-care global viscoelastic hemostatic techniques with several advantages. They use whole blood samples, which are more physiological compared with conventional plasma-based tests, require small volumes, and provide comprehensive and real-time data on coagulation/fibrinolysis. Many successful applications have been reported, including hepatobiliary/cardiovascular surgeries, transfusion therapy, and trauma; however, the routine use of these tests remains surprisingly low in relation to pregnancy and puerperium. 7 Systemic reviews of literature and meta-analyses 1,2 have not shown the routine use of viscoelastic point-of-care tests to improve important clinical outcomes except in cardiac surgery; this was validated by The UK National Institute for Health and Care Excellence (https ://www.nice.org.uk/guida nce/dg13). Although the TEG and ROTEM assays and the technology itself have been analytically validated 3 it is perhaps the clinical validation, applications, and recommendations in relation to pregnancy that still require perfection as future large studies are now available. The effectiveness of TEG and ROTEM as point-of-care tests, in reducing and guiding transfusion therapy is most studied in trauma and postpartum hemorrhage (PPH). 4-6 Other pregnancy-related bleeding or thrombotic disorders are much less studied.Literature shows limited uptake among clinicians regarding the use of TEG/ROTEM during pregnancy, 7-9 which is likely from a perceived lack of evidence. Indeed, there are currently no clinical guidelines on indications of these assays and the strength of available evidence regarding clinical correlates or efficacy remains unknown, with several contradictory opinions reported. A major barrier to improving the application of this technology in obstetrics remains the lack of studies that improve patient outcomes, and an international consensus (at least in key obstetric conditions beyond PPH is lacking).The aim of this project was to systematically review current evidence for the use of TEG/ROTEM in pregnancy and pregnancy-related complications and examine the existing scope of utilization in this context. We would like to clarify that this incorporates not only the use of these tests in assessing PPH and bleeding conditions, but also hypercoagulability and thrombosis risk. For basics about the assay and technology, refer to our previous publications. 10,11 | S E ARCH ME THODS FOR LITER ATURE RE VIE WA systematic 10-year critical literature review was performed by searching OVID versions of MEDLINE and EMBASE for all records between 2007 and 2017. Inclusion criteria were human studies published in English, presented as full manuscripts, with TEG/ROTEM

Systematic review of viscoelastic testing (TEG/ROTEM) in obstetrics and recommendations from the women's SSC of the ISTH

“…31,33 There is also debate regarding the sensitivity of TEG/ROTEM in detecting hypo-or hyperfibrinolysis. 3,4,63,105,106 Some studies using ROTEM CLI 30 and a modified ROTEM with addition of tissue plasma activator (tPA) failed to find any differences in fibrinolysis between pregnant and nonpregnant women. 68,105,107 However, a major flaw with the modified tPA-added model was that the concentration of tPA added was far greater than the maximum possible concentration of fibrinolysis inhibitors which would explain its insensitivity.…”

“…We believe it complements and adds to a recent communication by the International Society on Thrombosis and Haemostasis (ISTH) Women's Health Issues in Thrombosis and Haemostasis. 4 It presents in detail both the advantages and limitations of the technology as well as identifies gaps in areas of research and expands further to recommend future ideal studies to fill those gaps.…”

Assessing maternal clotting function with novel global coagulation assays: A prospective pilot study

“…Current data on GCAs to study the hypercoagulability of pregnancy are often limited by small sample sizes and studies do not evaluate the use of more than one GCA at a time 11 . By providing a more comprehensive assessment of the haemostatic profile, these GCAs may provide additional insight into the pathophysiology of hypercoagulability in the pregnant population and potentially assist VTE risk assessment as well as guide individualized thromboprophylaxis 11‐13 …”

Blood management in post-partum haemorrhage, including point of care coagulation tests

“…ROTEM and TEG can identify hypercoaguable states associated with pregnancy [31,33]. In future, with more evidence, there may be a role for viscoelastometric tests in VTE risk stratification, prevention and treatment [51].…”

“…It is important to be aware of some of the limitations pertaining to the use of ROTEM and TEG in PPH. There can be significant variability in precision of results between different machines and internal and external quality control is imperative to ensure accuracy of results [33,51,52]. These machines cannot assess the effect of hypothermia that can occur during PPH [31].…”