Letter: Warfarin and fetal abnormality

Neurological sequelae of intrauterine warfarin exposure

Warfarin embryopathy is a well-defined manifestation of intrauterine warfarin exposure. The embryopathy phenotype as it relates to the nervous system is broad and poorly recognised. We describe an adult with neurological sequelae of fetal warfarin exposure. We review previous cases with neurological sequelae and discuss the pathogenetic mechanism in light of recent research.

Congenital schizencephaly associated with in utero warfarin exposure

The warfarin embryopathy is a well-defined complex of fetal anomalies generally accepted to result from first trimester exposure. Optic atrophy and dilation of the cerebral cerebral ventricles associated with blindness, microcephaly, and mental retardation have been reported following second and third trimester exposure. In contrast to the consistent clinical features observed in the warfarin embryopathy, the CNS effects seen in fetuses exposed in the later trimesters share little in terms of specific lesion or long-term clinical outcome. A case of schizencephaly in a coumadin-exposed fetus is presented. This report offers supportive evidence that the CNS sequellae of this agent are the result of vascular accident and hemorrhage, not a direct effect on CNS morphogenesis. The molecular basis for the adverse effects of warfarin derivatives on the fetus are reviewed. Warfarin derivatives exert both their embryopathic and their fetopathic effects via pharmacologic action: inhibition of gamma carboxylation of osteocalcin and a similar carboxylation of the vitamin K dependent clotting factors. Therefore, we believe that warfarin exposure in the second or third trimesters of pregnancy is equally dangerous to the fetus as that in the first. Heparin may be a superior alternative to warfarin for the prevention of thromboembolic disease in pregnant women with cardiac valve prostheses.

Congenital Dandy Walker malformation associated with first trimester warfarin: a case report and literature review

While the warfarin embryopathy is well defined, central nervous system abnormalities associated with gestational warfarin exposure require further definition. Based on the timing of warfarin exposure in humans, it has been proposed that second- and third-trimester exposure predisposes to CNS abnormalities while first-trimester exposure more typically is associated with the warfarin embryopathy. A case is presented of a liveborn male with Dandy Walker malformation, agenesis of the corpus callosum, and Peter anomaly of the right eye who was exposed to warfarin between the 8th and 12th weeks of gestation who had none of the stigmata of the warfarin embryopathy. His is the first known case of exposure confined to the first trimester, and the fifth case of Dandy Walker malformation among a total of 15 CNS cases associated with this drug. This case offers evidence that Dandy Walker malformation may represent a distinct complication of in utero first-trimester exposure, and consideration of these particular abnormalities with exposure limited to a period prior to the known appearance of vitamin K-dependent clotting factors suggests that warfarin has a direct teratogenic effect on central nervous system morphogenesis.