Modified ACOG Safe Motherhood Initiative Guidelines Proposed for Thromboprophylaxis in Peripartum Women
Key findings
- The first part of this study examined the potential rates of pharmacologic thromboprophylaxis in 638 obstetric patients hospitalized at a single center using different scoring guidelines
- If prophylaxis were given at a risk score of ≥3 by ACOG criteria instead of ≥2, the percentage of antepartum women who'd receive prophylaxis would fall from 12% to 7%, and the percentage of postpartum women would fall from 24% to 11%. This was preferable to the British Royal College of Obstetricians and Gynecologists (RCOG) scoring algorithm
- In a separate analysis, over a six-year period, all cases of hospitalization-associated venous thromboembolism at the institution occurred in women with antepartum or postpartum ACOG scores ≥3
- In the absence of prospective, randomized data, it is reasonable to provide prophylaxis to both antepartum and postpartum patients when the risk score according to the ACOG guidelines is ≥3
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Obstetric patients may have risk factors for venous thromboembolism (VTE) that aren't accounted for in standard scoring systems, such as high parity, preeclampsia, bed rest and a history of ovarian hyperstimulation. Two major professional societies have proposed obstetric-specific scoring guidelines for antepartum and postpartum pharmacologic thromboprophylaxis:
- The Royal College of Obstetricians and Gynaecologists (RCOG) considers 24 risk factors; antepartum prophylaxis is recommended for a score of 3, or universally for hospitalizations over 72 hours; postpartum, at least 10 days of thromboprophylaxis is recommended at a risk score of 2
- The American College of Obstetricians and Gynecologists (ACOG) considers 17 factors but compared with RCOG allows more provider discretion; thromboprophylaxis is recommended during hospitalization only, at a score of 2 (both antepartum and postpartum admissions)
Christina Duzyj Buniak, MD, MPH, maternal-fetal medicine specialist in the Department of Obstetrics and Gynecology at Massachusetts General Hospital, Daniela Gomez, MD, of the University of Arizona College of Medicine-Phoenix, and colleagues have published evidence that changing the ACOG Safe Motherhood Initiative guidelines to provide thromboprophylaxis to peripartum women with a risk score ≥3 would prevent hospitalization-related VTE without excessive anticoagulation. Their findings appear in The Journal of Maternal–Fetal & Neonatal Medicine.
Study Methods
The study had two parts:
- Retrospective analysis of antepartum and postpartum ACOG and RCOG risk scores (not actual administration of thromboprophylaxis) for 638 patients hospitalized for maternity care at a regional perinatal center between July 1 and October 31, 2015
- A review of medical records related to obstetric hospitalizations between 2012 and 2018 to identify cases of VTE occurring from the first trimester through six weeks following delivery. Women admitted with VTE were excluded because hospital-based thromboprophylaxis would not have prevented their outcome
Antepartum Results
The proportion of the 638 patients who qualified for antepartum prophylaxis was:
- 20% at the RCOG threshold (score of 3)
- 12% at the ACOG threshold (score of 2)
- 7% (a 42% reduction) if the ACOG threshold were changed to 3
The differences between the three groups were significant (P<0.001 for each).
Postpartum Results
The proportion of patients who qualified for postpartum prophylaxis was:
- 53% at the RCOG threshold (score of 2)
- 24% at the ACOG threshold (score of 2)
- 40% if the RCOG threshold were 3
- 11% (a 54% reduction) if the ACOG threshold were 3
The differences between the four groups were significant (P<0.001 for each).
Is Modification of the Thresholds Adequately Sensitive?
Over the separate six-year study period, six women developed VTE during an obstetric hospitalization:
- Two women had a first-trimester miscarriage complicated by VTE; they were known to have thrombophilia and their risk scores were 4 by both ACOG and RCOG guidelines, and they were already receiving prophylaxis
- The other four women (one with antepartum VTE, three with postpartum VTE) had ACOG scores of 3 to 7 and RCOG scores of 3 to 8 but did not receive prophylaxis; one of them developed pulmonary embolism after a vaginal delivery, which is concerning because ACOG recommends considering prophylaxis only for women undergoing cesarean delivery
Applying the Findings to Practice
For now it's reasonable to provide thromboprophylaxis to both antepartum and postpartum patients when the risk score according to the ACOG guidelines is ≥3. Limiting postpartum prophylaxis to the immediate delivery hospitalization, as ACOG suggests, would target the highest-risk time period for VTE.
Thromboprophylaxis is not benign, so prospective, randomized data are required to evaluate whether the ACOG guideline benefits all peripartum women at risk of VTE without incurring unnecessary bleeding risk or excessive costs. Prospective data are especially needed for antepartum inpatients, in whom prophylaxis can also reduce access to regional anesthesia if labor ensues.
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