Assessment period i Antepartum and postpartum assessments use the same risk factors but different score thresholds. Antenatal (during pregnancy) Postnatal (after birth)
Previous VTE (except a single event related to major surgery) i RCOG scores any previous VTE 4 points, whether unprovoked, on estrogen, in pregnancy, or provoked by something other than major surgery (trauma, immobility, long-haul travel). A single event related to major surgery uses the 3-point row below instead.
Previous VTE provoked by major surgery i A single prior clot provoked by major surgery scores 3 points.
High-risk thrombophilia (antithrombin deficiency, protein C/S deficiency, antiphospholipid syndrome, homozygous Factor V Leiden or prothrombin G20210A) i Any single inherited or acquired high-risk thrombophilia scores 3 points.
Significant medical comorbidity (cancer, SLE, inflammatory bowel disease, nephropathy, sickle cell disease, current IV drug use) i Active inflammatory or systemic disease associated with hypercoagulability scores 3 points.
BMI before pregnancy i Pre-pregnancy or booking BMI. BMI 30-39 scores 1 point; BMI 40+ scores 2 points. Less than 30 (no points) 30-39 (obese) - 1 point 40 or above (morbidly obese) - 2 points
Age over 35 years i Maternal age over 35 scores 1 point.
Family history of unprovoked or estrogen-related VTE (first-degree relative) i An unprovoked or estrogen-related VTE in a parent, sibling or child scores 1 point.
Low-risk thrombophilia (heterozygous Factor V Leiden or prothrombin G20210A) i A single heterozygous thrombophilia without previous VTE scores 1 point.
Parity 3 or more (three or more previous births) i Three or more previous deliveries, not counting the current pregnancy, scores 1 point.
Current smoker i Active tobacco use at the time of assessment scores 1 point.
Gross varicose veins i Symptomatic or extensive varicose veins scores 1 point.
Pre-eclampsia in this pregnancy i Confirmed pre-eclampsia scores 1 point.
Assisted reproduction (ART / IVF) - antepartum only i Conception through assisted reproductive technology scores 1 point antenatally.
Multiple pregnancy (twins, triplets or more) i A multiple pregnancy scores 1 point.
Caesarean section performed in labour (emergency) i Emergency caesarean section scores 2 points.
Elective (planned) caesarean section i Planned caesarean section scores 1 point.
Mid-cavity or rotational operative delivery (forceps or rotational ventouse) i Instrumental deliveries other than simple outlet procedures score 1 point.
Prolonged labour (more than 24 hours) i Labour lasting longer than 24 hours scores 1 point.
Postpartum haemorrhage (more than 1 litre or requiring transfusion) i Significant postpartum blood loss scores 1 point.
Preterm birth (before 37 weeks) in this pregnancy i Birth before 37 completed weeks scores 1 point.
Stillbirth in this pregnancy i Intrauterine fetal death at or after 24 weeks scores 1 point.
Surgical procedure during pregnancy or puerperium (excluding perineal repair) i Any surgery under general or regional anaesthesia scores 3 points.
Hyperemesis gravidarum (requiring IV fluids or admission) i Severe vomiting causing dehydration and/or requiring hospital admission scores 3 points.
Ovarian hyperstimulation syndrome (OHSS) - first trimester only i OHSS is an especially high-risk transient factor and scores 4 points.
Current systemic infection (requiring antibiotics or hospitalisation) i Active systemic infection scores 1 point.
Immobility or significant dehydration (bed rest, long-haul travel, hyperemesis) i Reduced mobility not already counted in other factors scores 1 point.