title: Risk factors for pregnancy associated venous thromboembolism.
abstract: In an attempt to reduce the incidence of pregnancy associated venous thromboembolism (PA-VTE), some researchers have advocated screening of all women for the factor V(Leiden) mutation during early pregnancy. We have conducted a large retrospective study (over 72,000 deliveries) to determine if this would be useful. Sixty-two objectively confirmed venous thrombotic events (51 DVT, 11 PE) were recorded at two maternity units in the UK. The incidence of DVT was 0.71 per 1000 deliveries (95% CI 0.5-0.9) with 0.50 occurring in the antenatal period (95% CI 0.34-0.66) and 0.21 in the puerperium (95% CI 0.11-0.31). The incidence of PE was 0.15 per 1000 deliveries (95% CI 0.06-0.24), 0.07 antenatal (95% CI 0.01-0.13) and 0.08 in the puerperium (95% CI 0.02-0.14). Of these 62, 50 attended for follow-up and thrombophilia screening. 28% of all episodes of PA-VTE had no clinical risk factor for thrombosis or an identifiable thrombophilic abnormality. Deficiency of antithrombin was identified in 12% of individuals (95% CI 3-21) and the factor V(Leiden) mutation in 8% (95% CI 0.5-15.5). Based on estimates of the prevalence of the factor V(Leiden) mutation in the population, we estimate that the thrombotic risk for a woman during pregnancy or the puerperium with the defect is approximately 1 in 400-500. This figure would not lend support to the idea of random screening for the mutation in early pregnancy.
authors.affiliation: Department of Haematology, Royal Infirmary, Glasgow, Scotland, UK.
authors.forename: M D
authors.initials: MD
authors.lastname: McColl
authors.forename: J E
authors.initials: JE
authors.lastname: Ramsay
authors.forename: R C
authors.initials: RC
authors.lastname: Tait
authors.forename: I D
authors.initials: ID
authors.lastname: Walker
authors.forename: F
authors.initials: F
authors.lastname: McCall
authors.forename: J A
authors.initials: JA
authors.lastname: Conkie
authors.forename: M J
authors.initials: MJ
authors.lastname: Carty
authors.forename: I A
authors.initials: IA
authors.lastname: Greer
mesh_terms: D000328:Adult; D004789:Enzyme Activation; D005165:Factor V / Q000032:analysis* / Q000235:genetics; D005260:Female; D005787:Gene Frequency; D005820:Genetic Testing; D006801:Humans; D015994:Incidence; D007744:Obstetric Labor Complications / Q000453:epidemiology; D011225:Pre-Eclampsia / Q000453:epidemiology; D011247:Pregnancy; D011250:Pregnancy Complications, Hematologic / Q000453:epidemiology* / Q000209:etiology; D011486:Protein C / Q000378:metabolism; D011644:Puerperal Disorders / Q000453:epidemiology* / Q000209:etiology; D011655:Pulmonary Embolism / Q000453:epidemiology / Q000209:etiology; D012189:Retrospective Studies; D012307:Risk Factors; D012606:Scotland / Q000453:epidemiology; D013923:Thromboembolism / Q000453:epidemiology* / Q000209:etiology; D019851:Thrombophilia / Q000209:etiology* / Q000235:genetics; D013924:Thrombophlebitis / Q000453:epidemiology / Q000209:etiology
chemical_list: D011486:Protein C; C095381:factor V Leiden; D005165:Factor V