Pre-existing risk factors

Score

Previous VTE (except a single event related to major surgery)

4

Previous VTE provoked by major surgery

3

Known high-risk thrombophilia

3

Medical comorbidities cancer, heart failure; active systemic lupus erythematosus, inflammatory polyarthropathy or inflammatory bowel disease; nephrotic syndrome; type I diabetes mellitus with nephropathy; sickle cell disease; current intravenous drug user

3

Family history of unprovoked or oestrogen-related VTE in first-degree relative

1

Known low-risk thrombophilia (no VTE)

1

Age (> 35 years)

1

Obesity (BMI > 30/>40)

1/2

Parity ≥ 3

1

Smoker

1

Gross varicose veins

1

Obstetric risk factors

Pre-eclampsia in current pregnancy

1

ART/IVF (antenatal only)

1

Multiple pregnancy

1

Caesarean section in labour

2

Elective caesarean section

2

Mid-cavity or rotational operative delivery

1

Prolonged labour (>24 hours)

1

PPH (>1 L or transfusion)

1

Preterm birth < 37 + 0 weeks in current pregnancy

1

Stillbirth in current pregnancy

1

Transient risk factors

Any surgical procedure in pregnancy or puerperium except immediate repair of the perineum

3

Hyperemesis

3

Ovarian Hyperstimulation Syndrome (first trimester only)

4

Current systemic infection

1

Immobility, dehydration

1