Isolation and characterization of an antifactor V antibody causing activated protein C resistance from a patient with severe thrombotic manifestations.

A 44-year-old woman with a history of severe thrombotic manifestations presented with a markedly reduced activated protein C-sensitivity ratio (APC-SR). DNA sequencing of and around the regions encoding the APC cleavage sites in the factor Va molecule excluded the presence of the factor VLeiden mutation and of other known genetic mutations. No antiphospholipid antibodies were present in the patient's plasma and both prothrombin time and activated partial thromboplastin time were normal.

Effect of delivery modalities on the physiologic inhibition system of coagulation of the neonate.

The perinatal period is associated with an increased incidence of thromboembolic complications, which may occur in both the maternal and fetal circulation in otherwise normal and healthy adults and fetuses, and this may be related to the activation of the coagulation system at the time of parturition. The risk of these complications is generally much higher in neonates, who have decreased activity of the physiologic inhibition system of coagulation (PISC), including protein C, protein S and antithrombin, in comparison with adults. Therefore, any additional obstetric iatrogenic factors could predispose the neonate to an increased risk of thromboembolic complications.