VTE Risk Score Calculator
Assess VTE risk in pregnancy and postpartum.
For Healthcare Professionals Only
pre Existing Factors
obstetric Factors
transient Factors
Antenatal Risk
0
Low Risk
A score of ≥4 suggests consideration for LMWH prophylaxis from the first trimester.
Postnatal Risk
0
Low Risk
A score of ≥2 suggests consideration for LMWH prophylaxis for at least 10 days.
Venous Thromboembolism (VTE), which includes deep vein thrombosis (DVT) and pulmonary embolism (PE), is a leading cause of maternal morbidity and mortality in developed countries. Pregnancy and the postpartum period (the puerperium) are well-established hypercoagulable states, meaning there is an increased tendency for blood to clot. Therefore, systematic risk assessment is crucial for identifying women who may benefit from thromboprophylaxis (preventative treatment).
This interactive tool is based on the widely adopted risk assessment model from the UK's Royal College of Obstetricians and Gynaecologists (RCOG) Green-top Guideline. It is intended for use by healthcare professionals to stratify VTE risk and guide decisions about thromboprophylaxis.
This tool is for medical professionals only and is not a substitute for clinical judgment. All patient management decisions should be individualized and made in accordance with local guidelines and a full clinical evaluation.
The Physiology of VTE Risk in Pregnancy
During pregnancy, the body undergoes several changes, described by Virchow's triad, that increase the risk of VTE:
- Hypercoagulability: There is an increase in the levels of several clotting factors (like fibrinogen and Factor VIII) and a decrease in natural anticoagulants (like Protein S). This is a protective mechanism to reduce blood loss at delivery.
- Venous Stasis: The enlarging uterus compresses the pelvic veins and inferior vena cava, slowing blood flow in the legs.
- Endothelial Injury: Vessel damage can occur during delivery, whether vaginal or Cesarean.
The risk is present throughout pregnancy but is highest in the first trimester and, most significantly, in the first six weeks postpartum.
The Risk Assessment Model
The RCOG model uses a scoring system based on pre-existing, obstetric, and transient risk factors. Each factor is assigned points, and the total score determines the patient's risk level and the recommendation for starting thromboprophylaxis with Low Molecular Weight Heparin (LMWH). Risk should be assessed at the first antenatal booking and reassessed upon any hospital admission and immediately postpartum.
This tool allows you to check boxes for both the antenatal and postnatal periods to calculate two separate scores.
Pre-existing Risk Factors
These are risk factors present before or at the start of pregnancy. A previous VTE and high-risk thrombophilias (like Factor V Leiden homozygosity or antithrombin deficiency) are the most significant.
Obstetric Risk Factors
These are factors related to the pregnancy and delivery itself, such as pre-eclampsia, multiple pregnancy, and Cesarean section.
Transient Risk Factors
These are temporary situations that can increase risk, such as surgery during pregnancy, hyperemesis gravidarum leading to dehydration, or prolonged immobility.
Interpreting the Score and Management
The total score in each period (antenatal and postnatal) determines the management strategy.
Antenatal Period:
- Score ≥ 4: High Risk. Prophylactic LMWH should be considered from the first trimester and continued throughout pregnancy.
- Score = 3: Intermediate Risk. Prophylactic LMWH should be considered from 28 weeks of gestation.
- Score ≤ 2: Low Risk. Prophylaxis is generally not required unless other transient risk factors develop.
Postnatal Period:
- Score ≥ 2: Prophylactic LMWH should be considered for at least 10 days postpartum.
- Score = 1: Prophylaxis is generally not required, but good hydration and early mobilization are crucial.
For women with a previous VTE or high-risk thrombophilia, specialist consultation is always warranted, and they will often require higher doses or longer durations of treatment regardless of their score on this tool.
Clinical Judgment is Key
This scoring system is a guideline to promote systematic assessment. It is not a substitute for clinical judgment. The decision to initiate thromboprophylaxis must always balance the patient's risk of VTE against the potential risks of anticoagulation, such as bleeding, particularly around the time of delivery and neuraxial anesthesia. The patient's individual circumstances and preferences must always be part of the shared decision-making process.
Enter values to see the results.
Venous Thromboembolism (VTE), which includes deep vein thrombosis (DVT) and pulmonary embolism (PE), is a leading cause of maternal morbidity and mortality in developed countries. Pregnancy and the postpartum period (the puerperium) are well-established hypercoagulable states, meaning there is an increased tendency for blood to clot. Therefore, systematic risk assessment is crucial for identifying women who may benefit from thromboprophylaxis (preventative treatment).
This interactive tool is based on the widely adopted risk assessment model from the UK's Royal College of Obstetricians and Gynaecologists (RCOG) Green-top Guideline. It is intended for use by healthcare professionals to stratify VTE risk and guide decisions about thromboprophylaxis.
This tool is for medical professionals only and is not a substitute for clinical judgment. All patient management decisions should be individualized and made in accordance with local guidelines and a full clinical evaluation.
The Physiology of VTE Risk in Pregnancy
During pregnancy, the body undergoes several changes, described by Virchow's triad, that increase the risk of VTE:
- Hypercoagulability: There is an increase in the levels of several clotting factors (like fibrinogen and Factor VIII) and a decrease in natural anticoagulants (like Protein S). This is a protective mechanism to reduce blood loss at delivery.
- Venous Stasis: The enlarging uterus compresses the pelvic veins and inferior vena cava, slowing blood flow in the legs.
- Endothelial Injury: Vessel damage can occur during delivery, whether vaginal or Cesarean.
The risk is present throughout pregnancy but is highest in the first trimester and, most significantly, in the first six weeks postpartum.
The Risk Assessment Model
The RCOG model uses a scoring system based on pre-existing, obstetric, and transient risk factors. Each factor is assigned points, and the total score determines the patient's risk level and the recommendation for starting thromboprophylaxis with Low Molecular Weight Heparin (LMWH). Risk should be assessed at the first antenatal booking and reassessed upon any hospital admission and immediately postpartum.
This tool allows you to check boxes for both the antenatal and postnatal periods to calculate two separate scores.
Pre-existing Risk Factors
These are risk factors present before or at the start of pregnancy. A previous VTE and high-risk thrombophilias (like Factor V Leiden homozygosity or antithrombin deficiency) are the most significant.
Obstetric Risk Factors
These are factors related to the pregnancy and delivery itself, such as pre-eclampsia, multiple pregnancy, and Cesarean section.
Transient Risk Factors
These are temporary situations that can increase risk, such as surgery during pregnancy, hyperemesis gravidarum leading to dehydration, or prolonged immobility.
Interpreting the Score and Management
The total score in each period (antenatal and postnatal) determines the management strategy.
Antenatal Period:
- Score ≥ 4: High Risk. Prophylactic LMWH should be considered from the first trimester and continued throughout pregnancy.
- Score = 3: Intermediate Risk. Prophylactic LMWH should be considered from 28 weeks of gestation.
- Score ≤ 2: Low Risk. Prophylaxis is generally not required unless other transient risk factors develop.
Postnatal Period:
- Score ≥ 2: Prophylactic LMWH should be considered for at least 10 days postpartum.
- Score = 1: Prophylaxis is generally not required, but good hydration and early mobilization are crucial.
For women with a previous VTE or high-risk thrombophilia, specialist consultation is always warranted, and they will often require higher doses or longer durations of treatment regardless of their score on this tool.
Clinical Judgment is Key
This scoring system is a guideline to promote systematic assessment. It is not a substitute for clinical judgment. The decision to initiate thromboprophylaxis must always balance the patient's risk of VTE against the potential risks of anticoagulation, such as bleeding, particularly around the time of delivery and neuraxial anesthesia. The patient's individual circumstances and preferences must always be part of the shared decision-making process.