Introduction: Warfarin exposure exhibits teratogenic effects most during six to 12 weeks of gestation. Dandy-Walker Malformation is a rare central nervous system (CNS) complication of a fetus exposed to warfarin in the first trimester. It has scarcely been reported on in literature, overshadowed by the more common warfarin embryopathy of bone and cartilage in first trimester or the CNS effects of exposure in later trimesters as a result of fetal haemorrhages.
Case presentation: This case describes a 36-year-old multigravida woman of Cook Islander origin with five previous spontaneous vaginal deliveries who had an unplanned pregnancy, incidentally detected at 11+5 weeks of gestation on pelvic ultrasound. She has a significant cardiac history - rheumatic heart disease with mechanical aortic valve replacement, mitral valve repair and tricuspid valve annuloplasty – which she is on lifelong warfarin therapy. She previously had suffered a right middle cerebral artery infarct in the setting of ceasing anticoagulation for an elective haemorrhoidectomy. The morphology scan detected severe hydrocephalous, and a subsequent tertiary morphology scan at 23+1 weeks of gestation diagnosed the fetus with Dandy-Walker malformation with associated severe hydrocephalus and secondary perforation across the anterior midline. Fetal demise was confirmed on USS at 31+1 weeks of gestation with suspected fetal haemorrhages. The woman was transferred to a tertiary hospital for delivery and anticoagulation management during planned induction of labour under Maternal Fetal Medicine with cardiology input.
Conclusion: This case report provides evidence that warfarin exposure in the first trimester has a direct teratogenic effect on CNS morphogenesis, and can result in Dander-Walker malformation. This case demonstrates that pregnant women with significant cardiac history on therapeutic anticoagulation require meticulous and multidisciplinary approach to therapeutic anticoagulation management at preconception, during pregnancy, intrapartum and post-partum to ensure effects to mother and fetus are recognised and minimised.