Internal jugular vein thrombosis caused by resistance to activated protein C as a complication of ovarian hyperstimulation after in-vitro fertilization.

We present a case of a 24 year old woman who became pregnant (twins) after human menopausal gonadotrophin (HMG)-induced ovarian stimulation, in-vitro fertilization (IVF) and subsequent embryo transfer. She developed a right internal jugular vein thrombosis as a complication of severe ovarian hyperstimulation syndrome (OHSS) 28 days after embryo transfer. The thrombosis developed in spite of anticoagulation with low-dose heparin. Later a resistance to activated protein C (APC) or Dahlbäck disease was diagnosed. Due to a new test procedure (accelerin inactivation test), the diagnosis was possible even under anticoagulation treatment. The coincidence of hyperstimulation and internal jugular vein thrombosis with the concurrent diagnosis of resistance to APC has not been published previously. The benefit of general screening for resistance to APC before admission to the IVF programme should be weighed. Targeted selection of a group of high-risk women would therefore be made possible.