Treatment of thromboembolism in pregnancy

Suspected DVT in pregnancy should be investigated with duplex ultrasono-graphy and venography if necessary. A raised concentration of d-dimers or other fibrin degradation products may help to confirm the diagnosis. Suspected PE in pregnancy should be investigated with chest radiography, arterial blood gas analysis and electrocardiography, followed by a ventilation/perfusion scan. Increasingly, non-invasive imaging technique such as spiral computerised tomography, magnetic resonance imaging and specialised echocardiography are being used to diagnose PE.

Treatment of thromboembolism is with intravenous heparin initially (although subcutaneous low-molecular weight heparins (LMWHs) are increasingly used) and should not be delayed whilst awaiting investigation. Warfarin is associated with fetal abnormalities and in particular should be avoided in the first trimester and after 36 weeks' gestation. Acute treatment is followed by subcutaneous prophylactic heparin. It had been thought that prophylactic heparin caused stillbirth, prematurity and haemorrhage but more recent reviews controlling for maternal comorbidity have cast doubt on this assertion. Prophylaxis with LMWHs is now recommended because their use is associated with a lower incidence of osteoporosis and thrombocytopenia than unfractionated heparin, they require less monitoring, and they may be given as a once daily dosage. However, LMWHs have a prolonged action and are only partially reversible with protamine, meaning that LMWH prophylaxis may delay administration of regional analgesia (see Chapter 100, Coagulopathy, p. 240) and can be a problem where pregnancy is complicated by ante- or postpartum bleeding.

Massive PE may require dispersion under radiological control or open embolec-tomy. Administration of potent intravenous fibrinolytic drugs may result in massive obstetric haemorrhage.

The use of vena caval filters in pregnancy is felt by many authors to be contraindicated though they have been used.

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