Chapter 3 – Management of Deep-Vein Thrombosis and Pulmonary Embolism


Key Implications

Chapter 3 Management of Deep-Vein Thrombosis and Pulmonary Embolism Antepartum, Intrapartum and Postpartum

Chu Chin Lim and Tahir A. Mahmood

Key Facts

Definition Venous thromboembolism (VTE) is a condition in which a blood clot (thrombus) develops, commonly in the deep veins of the lower limbs, and this is called deep vein thrombosis (DVT). The majority of DVT in pregnancy are iliofemoral with a greater risk of both embolisation and recurrence. A thrombus may detach from its site of origin in the vein (embolus) and migrate through the blood stream to reach the lungs (pulmonary thromboembolism [PTE]). Venous thromboembolism has multiple contributory risk factors.


  • Distal or calf vein thrombosis

  • Acute DVT occurs in one of the three major paired veins, below the popliteal vein (posterior tibial, anterior tibial, peroneal) in the calf.

  • Proximal venous thrombosis

  • Acute DVT occurs in the popliteal vein or higher: superficial femoral or common femoral vein, iliac vein and vena cava.

  • Upper extremity venous thrombosis

  • They are generally classified separately from classic DVT. They occur above the right atrium, most frequently in the subclavian, axillary or internal jugular veins.

  • Incidence: 1–2 per 1000 pregnancies

Key Implications


  • Early identification of women at high risk of developing VTE during pregnancy, labour and postpartum

  • Pulmonary embolism has a case fatality rate of approximately 1%, with a recurrent risk of 1.15%in future pregnancies.

  • Identification of women at increased risk of arterial thrombosis

  • Identification of women at increased risk of bleeding while on treatment with anticoagulants

  • Hospitalisation and access to high dependency unit (HDU) care secondary to low oxygen lung perfusion

  • Post-thrombotic syndrome including leg pain, swelling, dermatitis, dependent cyanosis, ulcers and varicosities (risk 30%–60%)

Complications related to long-term use of anticoagulants:

  • Major postpartum haemorrhage (1.98%)

  • Osteoporosis-related fractures (0.04%)

  • Heparin-induced thrombocytopenia (HIT) which is substantially lower with use of low-molecular-weight heparin (LMWH)

  • Allergic skin reaction (1.8%)

Radiological investigations/related complications:

  • Increased life-time risk of breast cancer 13.6% (background risk of 1/200) with computerized tomography pulmonary angiography (CTPA)


  • A ventilation–perfusion (V/Q) scan carries an increased risk as compared to CTPA of childhood cancers to 1 per 280,000 (background risk of 1 per 1,000,000).

  • The radiation dose to the fetus from a chest x-ray performed during pregnancy is negligible.

  • Hypothyroidism if iodinated contrast medium is used with CTPA.

  • Fetal death: from the use of thrombolytic agents.


  • Clinical negligence claims due to delay in diagnosis and suboptimal treatment

  • Patient not appropriately counselled as regards long-term radiation risks to her and to the unborn baby

Patient Information

  • Patients should be informed about all aspects of VTE including seriousness of the disease process, risks related to each investigation and their implications. Counselling should include treatment benefits and risks. Every effort should be made to help women make informed choices about every aspect of their management where appropriate [1, 2].

  • Patients who had a suspected DVT but negative ultrasound and on no treatment should be advised that they should seek urgent advice and further assessment if they develop symptoms consistent with VTE such as increased limb pains or swelling, sudden onset of breathlessness, chest or back pain, coughing or spitting up blood and any episode of collapse.

  • Explain to the woman about the increased risk of VTE while using combined oral contraceptives/ hormone replacement treatment.

Key Pointers

Magnitude of the Problem

There is an approximately 10-fold increased risk during pregnancy compared with non-pregnant and 25-fold increased risk compared with non-pregnant/ non-puerperal during puerperium, and this risk is considerably increased among women with known thrombophilia. Pulmonary embolism has been the leading direct cause of maternal death in the UK (1.56 per100 000 maternities) [3, 4].

Antenatal Screening and Thromboprophylaxis

The rationale for prophylaxis is based on its efficacy, the clinically silent nature of VTE, its prevalence in pregnant or puerperal patients and its potentially disabling or fatal consequences. More than 40% of antenatal VTE occur in the first trimester of pregnancy. The confidential enquiries into maternal deaths report in the United Kingdom found that two-thirds of antenatal fatal pulmonary embolism occurred in the first trimester [5]. Therefore, every effort should be made to instigate antenatal thromboprophylaxis in the first trimester of pregnancy. Antenatal risk assessment should start at the time of first booking visit to the hospital. Women with multiple risk factors (three or more), those with a previous unprovoked VTE or previous recurrent VTE and those with multiple thrombophilia defects should be offered thromboprophylaxis with LMWH antenatally [6].

Furthermore, women with a history of recurrent VTE who are on warfarin should be switched over to LMWH as soon as pregnancy is confirmed.

All known identifiable risk factors for VTE have to identified at the booking visit (Table 3.1). These can be classified at high, intermediate or low risk for VTE and managed accordingly. Each woman’s risks need to be continually reviewed throughout pregnancy and during the intrapartum period. A note should also be made of conditions that can increase complications following thromboprophylaxis.

Table 3.1 Suggested algorithm (1) for risk identification and treatment of venous thromboembolism

Antenatal risk assessment for venous thromboembolism: adjusted odds ratio where available
High risk Intermediate risk Low risk

Single previous VTE (AOR: 24)

Thrombophilia or family history


Previous recurrent VTE (>1)

Requires antenatal prophylaxis with LMWH

Single previous VTE with no family history or

Thrombophilia + but no VTE

Medical comorbidities, e.g. heart or lung disease, systemic lupus erythematosus (AOR:8.7), inflammatory conditions, nephrotic syndrome, sickle cell disease, chronic HIV, intravenous drug user

Surgical procedure, e.g. appendicectomy

Consider antenatal prophylaxis with LMWH

Seek expert team advice

Age>35 years

Obesity BMI>30 kg/m2): 2- to 5-fold increase

Parity ≥3 (AOR: 3.4)

Smoker (10–30/day): (AOR 1.4, 3.4)

Gross varicose veins (AOR: 2.7), current systemic infection

Heterozygous factor V Leiden and prothrombin G20210 A without prior Hx of VTE (risk <1%)

Immobility, e.g. paraplegia, symphysis pubis

Dysfunction with immobility, long-distance travel, dehydration/hyperemesis

Preeclampsia (AOR: 2.9, 3.1)


Multiple pregnancy/assisted reproductive treatment

Mobilisation and avoidance of dehydration: three or more risk factors, treat as intermediate

Additional intrapartum risk factors

Preeclampsia (AOR: 2.9, 3.1)

Dehydration/hyperemesis/OHSS (AOR: 2.5)

Multiple pregnancy or assisted reproduction (ART)

(AOR: 4.3)

Caesarean section in labour (AOR: 2.7, 3.6)

Elective caesarean section (AOR:2.1)

Mid-cavity or rotational forceps

Prolonged labour (>24 hours)

PPH (>1 L or blood transfusion) (AOR: 4.1)

Identification of women at increased bleeding risk when on anticoagulation treatment

Haemophilia or other known bleeding disorder (e.g. von Willebrand’s disease or acquired coagulopathy)

Active antenatal or postpartum bleeding

Women considered at increased risk of major haemorrhage

(e.g. placenta praevia)

Thrombocytopenia (platelet count <75 × 109)

Acute stroke in previous 4 weeks (haemorrhagic or ischaemic)

Severe renal disease (glomerular filtration rate <30 mL/minute/1.73 m2)

Severe liver disease (prothrombin time above normal range or known varices)

Uncontrolled hypertension (blood pressure > 200 mm Hg systolic or >120 mm Hg diastolic)

Transient risk factors

Postpartum infection (AOR: 4.1)

Immobility (AOR: 7.7)

Surgical procedure in pregnancy + haemorrhage or ≤6 weeks postpartum (AOR: 6.2, 12)

Obstetric haemorrhage (AOR: 9); transfusion (AOR: 7.6)

Antenatal and postnatal prophylactic dose of LMWH

Weight <50 kg = 20 mg enoxaparin/2500 units of dalteparin/3500 units of tinzaparin daily

Weight 50–90 kg = 40 mg enoxaparin/5000 units of dalteparin/4500 units of tinzaparin daily

Weight 91–130 kg = 60 mg enoxaparin/7500 units of dalteparin/7000 units of tinzaparin daily

Weight 131–170 kg = 80 mg enoxaparin/10 000 units of dalteparin/9000 units of tinzaparin daily

Weight >170 kg = 0.6 mg/kg/day enoxaparin; 75 units/kg/day dalteparin/75 units/kg/day of tinzaparin

AOR, adjusted odds ratio; LMWH, low-molecular-weight heparin; OHSS, ovarian hyperstimulation syndrome; PPH, postpartum haemorrhage; VTE, venous thromboembolism.

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May 9, 2021 | Posted by in OBSTETRICS | Comments Off on Chapter 3 – Management of Deep-Vein Thrombosis and Pulmonary Embolism
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