Venous thromboembolism: comparison of pregnancy-specific risk scoring systems for pharmacoprophylaxis in hospitalised maternity patients

Large prospective clinical trials are needed to validate the scoring threshold for pharmacoprophylaxis.

Key Takeaway

  • In this cohort of hospitalised maternity patients, the use of American College of Obstetricians and Gynecologists (ACOG) prophylaxis guidelines at an increased threshold would potentially prevent all venous thromboembolism (VTE)-related hospitalisation without excessive anticoagulation.
  • The percentage of antepartum and post-partum women who would receive prophylaxis would fall from 12% to 7% and from 24% to 11%, respectively, if pharmacoprophylaxis was to be performed at a threshold score of 3 instead of 2 by ACOG criteria.

Why This Matters

  • Findings advocate pharmacoprophylaxis for both antepartum and post-partum patients using an ACOG risk scoring guideline at a threshold of ≥3 if thromboprophylaxis is to be implemented.

Study Design

  • This retrospective cohort study included 638 patients (mean maternal age, 30 years) hospitalised for maternity care over a 4-month period between July and October 2015.
  • Patients were assigned both an antepartum and post-partum risk score using ACOG and Royal College of Obstetricians & Gynecologists (RCOG) guidelines.
  • Obstetric hospitalisation over 6 years was assessed for any perinatal VTE occurring from the first trimester up to 6 weeks following delivery.
  • The percentage of patients in whom thromboprophylaxis would be recommended using both guidelines was compared for the antepartum and post-partum score.
  • A simplified universal threshold of 3 was also evaluated.
  • Funding: None disclosed.

Key Results

  • The median baseline antepartum score based on RCOG and ACOG criteria was 1 (25th-75th percentile interval, 0-2; range, 0-10) and 0 (25th-75th percentile interval, 0-1; range, 0-11), respectively.
  • In antepartum patients, 20% vs 12% of women would require treatment based on baseline risk characteristics using RCOG vs ACOG scoring thresholds (P<0.001).
  • Among antepartum patients, 7% (42% less) would receive treatment by ACOG criteria if prophylaxis was performed at an increased threshold score of 3.
  • Overall, 15 patients had an antepartum admission preceding their delivery, and 100% would have received pharmacoprophylaxis based on RCOG criteria because of prolonged hospitalisation over 3 days.
  • As per ACOG criteria, 40% (20% by the increased threshold score of 3) of these patients would have received pharmacoprophylaxis.
  • The median baseline post-partum score was 2 (25th-75th percentile interval, 0-4; range, 0-13) based on RCOG criteria and 1 (25th-75th percentile interval, 0-1; range, 0-11) based on ACOG criteria.
  • In post-partum patients, 53% vs 24% would require treatment based on RCOG vs ACOG guidelines (P<0.001).
  • Among post-partum patients, 40% and 11% would receive treatment by RCOG and ACOG criteria, respectively, if prophylaxis was performed at an increased threshold score of 3 (P<0.001 for difference.
  • In 6 years, 6 women had VTE events after an obstetric hospitalisation.


  • The sample size was small and underpowered.
  • This study was of risk scores and not of women who received pharmacoprophylaxis.
  • The comparison was limited to RCOG and ACOG risk scores.

    Gomez D, Orfanelli T, Awomolo A, Doulaveris G, Rosen T, Duzyj C. A comparison of pregnancy-specific risk scoring systems for venous thromboembolic pharmacoprophylaxis in hospitalized maternity patients. J Matern Fetal Neonatal Med. 2020 Oct 11 [Epub ahead of print]. doi: 10.1080/14767058.2020.1832072. PMID: 33043758

MAT-BH-2200296/v2/Apr 2022