Thrombophilia can be defined as a predisposition to thrombosis.
Abnormalities in haemostasis that are associated with clinical thrombophilia include heritable defects,
such as mutations in the genes encoding the natural anticoagulants antithrombin,
protein C and protein S,
or clotting factors prothrombin and factor V,
and adquired factors defects,
such as antiphospholipids.1,2,3,4 The most common acquired thrombophilia’s are antiphospholipids,
which comprise lupus inhibitors and anticardiolipin antibodies.5,6,7,8 Women with thrombophilic defects have been shown to be at increased risk,
not only of pregnancy associated thromboembolism,
but also of others vascular complications of pregnancy,
including pre-eclampsia and fetal loss.9,10 Routine thrombophilia screening of all women attending antenatal clinics is not recommended.
Because some thrombophilic defects – for example,
type 1 antithrombin deficiency and antiphospholipids – are associated with high risk of recurrent thrombosis or other pregnancy complications,
it is suggested that selected women (those with a personal or confirmed family history of venous thromboembolism or with a history of recurrent fetal loss) are screened for these defects to allow pregnancy management planning.1
Pregnancy is hypercoagulable state.
The field of thrombophilia; the tendency to thrombosis,
has been developed rapidly and has been linked to many aspects of pregnancy.2,4
Deficiencies of protein S C and antithrombin are rare and each of them is found in about 3% of patients with thrombosis.
Recently,
three important inherited thrombophilia’s were discovered which are responsible of the majority of thromboembolic events in patients with otherwise no apparent risk of thrombosis.
Resistance to activated protein C caused by an adenine 506 guanine (A506G) mutation in factor V (factor V Leiden) has been linked with an increased risk of venous thromboembolism.9,10 Heterozygosity for the factor V (FV) Leiden mutation is found in about 5% of the population and the mutation is responsible of 20-30% of venous thromboembolism events.
A recently described guanine 20210 adenine mutation in prothrombin is associated with higher plasma prothrombin concentrations and increased risk for venous thromboembolism and cerebral vein thrombosis.
Homozygosis for the cytosine 677 thymine (C677T) mutation in methylenetetrahydrofolate reductase (MTHFR) results in decreased synthesis of 5-methyltetrahydrofolate,
the primary methyl donor in the conversion of homocysteine to methionine and the resulting increase in plasma homocysteine concentrations is a risk factor for thrombosis.11 The mutation is responsible for reduced MTHFR activity and is the most frequent cause of mild hyperhomocysteinaemia and can be found in 5-15% of the population.
2,3,4
There is growing evidence that women with thrombophilia are at increased risk,
not only of pregnancy-related venous thromboembolism (VTE),
but also other vascular pregnancy complications,
including fetal loss,
pre-eclampsia and intra-uterine growth restriction (RCIU).1 Many studies have now examined the association between thrombophilia and pregnancy complications,
often with differing results.
In addition,
clinical studies have been performed,
using Doppler ultrasonography,
to assess the uterine placental circulation in women with thrombophilia.
Doppler studies of the umbilical artery in cases of intrauterine growth restriction have shown a high systolic to diastolic ratio (S/D) ratio,
suggesting an increase in the resistance of the placental small vessels.
When these placental vessels were examined after delivery,
significant differences were found in comparison with placental vessels of normal pregnancies.
Most of the Doppler studies of the umbilical and uterine arteries in pregnancies with thrombophilia were performed in women with antiphospholipid antibodies.10
The purpose of this study is to analyze the association between inherited thrombophilia and obstetrics abnormalities and adverse fetal outcomes using Ultrasound and Doppler.