Abstract
Background
Thromboprophylaxis is commonly required following caesarean section. However the effect
of thromboprophylactic dosages of subcutaneous heparin on coagulation is unknown because
conventional laboratory tests are largely unaffected. The aim of this study was to
determine if thromboelastography could detect and quantify the effect of unfractionated
heparin on coagulation profile when given at the time of surgery.
Methods
Nineteen women undergoing elective caesarean section were recruited. Blood samples
collected before and after administration of subcutaneous unfractionated heparin 7500 IU underwent thromboelastography using both plain and heparinase cuvettes. Anti-factor
Xa levels were also measured.
Results
There was a significant difference in R times between plain and heparinase samples (−10.6%, P = 0.0072) indicating that thromboelastography could detect an effect of unfractionated
heparin. Compared to baseline there were significant decreases of R times in plain (−20.4%, P = 0.033) and heparinase (−28.8%, P = 0.0001) samples despite the administration of unfractionated heparin. Anti-factor
Xa levels were virtually undetectable (mean 0.01 U/mL).
Conclusion
Thromboelastography was able to detect and quantify the effect of unfractionated heparin
on blood coagulability, an effect not detected by conventional laboratory tests. Thromboelastography
demonstrated a pro-coagulant effect of surgery that was only partially mitigated by
the use of unfractionated heparin. In this study, at a dose of 7500 IU subcutaneous unfractionated heparin appears to have little anticoagulant effect.
Keywords
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Article info
Publication history
Published online: June 06, 2011
Accepted:
March 22,
2011
Presented in part at the Obstetric Anaesthetists’ Association Annual Meeting, Jersey; May 2009.Identification
Copyright
© 2011 Elsevier Ltd. Published by Elsevier Inc. All rights reserved.
