Heterozygote carriers of mutations in the F11 gene, encoding Factor XI, have normal coagulation by thrombo-elastography during pregnancy

Abstract Background Evidence to guide clinical decision-making in pregnant women who are usually asymptomatic, but identified as heterozygote carriers of F11 mutations, is lacking. We hypothesized that women identified on prenatal screening as heterozygous for a mutation in the F11 allele would have minimal evidence of an in vitro coagulation abnormality. Methods We prospectively enrolled women identified by prenatal screening as F11 mutation carriers and presumed to be normal pregnant women as controls. We collected blood during antepartum visits or at presentation for delivery and assessed FXI coagulant activity level as well as whole-blood coagulation by thrombo-elastography. Results F11 mutation carriers had lower serum FXI activity levels than controls (51.2 ± 8.5% vs 94.1 ± 19.4%; P Conclusions Despite lower Factor XI activity in the F11 mutation group, we found minimal differences in whole-blood measures of coagulation using thrombo-elastography. These findings support our hypothesis that a single copy of an F11 mutation does not produce significant evidence of an in vitro coagulation abnormality. Thrombo-elastography might be useful in determining the risk of neuraxial anesthesia in pregnant women, but additional work is required to establish the validity of this test.