Internal jugular vein thrombosis following in-vitro fertilization in a woman with protein S deficiency and heterozygosity for the prothrombin 3' UTR mutation, despite anticoagulation with heparin.

We report the case of a 31-year-old woman with protein S deficiency and heterozygosity for the prothrombin 3' UTR mutation who developed an internal jugular vein thrombosis despite therapeutic anticoagulation with a low molecular weight heparin, following in-vitro fertilization. This case indicates that the stimulus to thrombosis in such women is intense and can occur despite apparent therapeutic anticoagulation. Close attention should, therefore, be paid to any women with a personal or family history of thrombosis and the potential thrombotic risks associated with assisted conception must be discussed.