Assisted Reproduction Techniques. Группа авторов
Чтение книги онлайн.
Читать онлайн книгу Assisted Reproduction Techniques - Группа авторов страница 45
![Assisted Reproduction Techniques - Группа авторов Assisted Reproduction Techniques - Группа авторов](/cover_pre960779.jpg)
All patients proceeding to IVF treatment should be individually assessed for their risk of thrombotic complications (Table 8.1) [8].
Thrombotic disorders
Inherited thrombophilia
Fifteen to 25% of Caucasian populations have thrombophilic risk factors. Heritable thrombophilias include deficiencies of the endogenous anticoagulants, antithrombin, protein C and protein S, and genetic mutations in procoagulant factors such as factor V Leiden and prothrombin G20210A, and the thermolabile (C677T) variant of the methylene tetrahydro‐folate reductase (MTHFR) gene. The prevalence of these thrombophilias is variable, with significant ethnic variation. For example, 2–7% of Western European populations are heterozygous for factor V Leiden and prothrombin G20210A compared with less than 1% of Chinese.
Table 8.1 Risk factors for venous thromboembolism (VTE) [8].
History markers | |
---|---|
Previous venous or arterial thromboembolism | |
Obesity (body mass index ≥30 kg/m2) | |
Gross varicose veins | |
Previous/current intravenous drug abuse | |
Age over 35 years | |
Parity >=3 | |
Smoker | |
Ovarian hyperstimulation syndrome | |
Dehydration | |
Immobility | |
Prolonged bed rest | |
Prolonged travel | |
Medical conditions (such as infections, malignancies, cardiac conditions, active systemic lupus erythematosus, inflammatory bowel disease, sickle cell disease, type 1 diabetes with nephropathy, nephrotic syndrome etc.) | |
Inherited thrombophilia | Odds ratio for VTE (95% confidence interval) |
Factor V Leiden heterozygous | 9.2 (5.44–12.70) |
Factor V Leiden homozygous | 34.40 (9.86–120.05) |
Antithrombin deficiency | 4.69 (1.30–16.96) |
Protein C deficiency | 4.76 (2.15–10.57) |
Prothrombin G20210A heterozygous | 6.80 (2.46–19.77) |
Prothrombin G20210A homozygous | 26.36 (1.24–559.29) |
Family history of VTE in one or more first degree relatives | 2.7 (1.8–3.8) |
Acquired thrombophilia | |
Lupus anticoagulant | |
Anticardiolipin antibodies |
Acquired thrombophilia
Antiphospholipid syndrome is the most common acquired thrombophilia associated with an increased risk of recurrent miscarriage and pregnancy morbidity. Antiphospholipid syndrome is present if at least one of the clinical criteria and one of the laboratory criteria shown in Box 8.1 are present [9].
Management options
There is currently little evidence to support universal screening for thrombophilia in pregnancy or prior to IVF for the prevention of VTE [10]. However, screening for thrombophilia should be considered in women with a history of recurrent miscarriage, or personal or family history of VTE. The association between thrombophilia and OHSS is conflicting. According to one study thrombophilia is thought to be associated with a high risk of developing OHSS [11], and this has been proposed as an additional reason for screening for thrombophilia in women with a family or personal history of thrombosis prior to undergoing ovarian stimulation and in women who have developed OHSS. However, another study failed to show an increased prevalence of thrombophilia in women with severe OHSS undergoing ovulation induction. Therefore, the clinical and cost effectiveness for screening in this context could not be demonstrated [12].
Screening for thrombophilias should include the following:
plasma antithrombin
proteins S and C
antiphospholipid antibodies
factor V Leiden mutation
MTHFR C677T
The management of the woman with a single previous VTE has been controversial, but data from studies of pregnancy may guide therapy in the context of IVF. In a woman with a previous VTE that was not related to pregnancy or oral contraceptive use, and in whom no thrombophilia or other additional risk factor is present, thromboprophylaxis probably need not be prescribed [13]. However, in women with a previous VTE and underlying thrombophilia, or where the VTE