Prolonged activated partial thromboplastin time in pregnancy: a brief report. 
Limited data are available regarding causes of prolonged activated partial thromboplastin time (aPTT) in otherwise normal pregnancies.  We retrospectively evaluated clinical data of pregnant women in whom an elevated aPTT was noted on routine prenatal testing.  Our intent was to identify various causes of prolonged aPTT and to evaluate whether the pregnancies were adversely affected.  A retrospective review of medical records of 36 pregnant patients with a prolonged aPTT as the sole abnormal coagulation test seen in the outpatient department of a tertiary care hospital over a period of 4 years.  Patients' median age was 26 (range, 19-41) years and median duration of gestation period was 19 (range, 8-38) weeks.  Fifteen patients were primigravida.  Of 36 patients, repeated aPTT values were normal in 24 (67%) patients, whereas 12 (33%) patients had persistently elevated aPTT values.  Factor XI deficiency was found in 5 patients, lupus anticoagulant in 3 patients, elevated anticardiolipin antibody in 2 patients, and low von Willebrand Factor level in 1 patient.  Overall, 23 patients delivered.  No patients experienced excessive bleeding or thromboembolism.  Factor XI deficiency and antiphospholipid antibody were 2 major abnormalities identified in patients with prolonged aPTT.  These coagulopathies were not associated with excessive bleeding or thromboembolism.  Repeat normal aPTT in approximately 2 thirds of patients suggests that proper sample collection and processing are important for coagulation assays to avoid erroneous clotting times.