Prevention and management of venous thromboembolism in pregnancy: cutting through the practice variation

Low-molecular-weight heparin and preeclampsia - does the sword cut both ways? Three case reports and review of literature

BACKGROUND

Low-molecular-weight heparins (LMWH) are the most commonly used anticoagulants during pregnancy. It is considered to be the drug of choice due to its safety in not crossing placenta. Considering the beneficial effect in the improvement of microcirculation, prophylactic application of LMWH in patients with preeclampsia became a trend. However, the bleeding risk related with LMWH in preeclampsia patients has seldomly been evaluated. This current study aimed to identify the potential risks regarding LMWH application in patients with preeclampsia.

CASE SUMMARY

Herein we present a case series of three pregnant women diagnosed with preeclampsia on LMWH therapy during pregnancy. All the cases experienced catastrophic hemorrhagic events. After reviewing the twenty-one meta-analyses, the bleeding risk related with LMWH seems ignorable. Only one study analyzed the bleeding risk of LMWH and found a significantly higher risk of developing PPH in women receiving LMWH. Other studies reported minor bleeding risks, none of these were serious enough to stop LMWH treatment. Possibilities of bleeding either from uterus or from intrabdominal organs in preeclampsia patients on LMWH therapy should not be ignored. Intensive management of blood pressure even after delivery and homeostasis suture in surgery are crucial.

CONCLUSION

Consideration should be given to the balance between benefits and risks of LMWH in patients with preeclampsia.

Racial and ethnic disparities in eligibility for postpartum venous thromboembolism prophylaxis in the United States

BACKGROUND

Postpartum venous thromboembolism (VTE) incidence differs by race and ethnicity in the United States. However, it is unclear whether the eligibility criteria for postpartum VTE prophylaxis mirror this disparity.

OBJECTIVE

To characterize the prevalence of risk factors and eligibility for postpartum VTE prophylaxis, among US Birthing people, stratified by race and ethnicity.

METHODS

We analyzed the National Inpatient Sample from October 2015 to December 2019, using diagnosis and procedure codes to identify postpartum individuals and their VTE risk factors. We compared proportion of delivery hospitalizations meeting eligibility for thromboprophylaxis stratified by race or ethnicity, according to American College of Gynecology and Obstetrics, American College of Chest Physicians, Royal College of Obstetricians and Gynecologists (RCOG), and American Society for Hematology guidelines.

RESULTS

Among a national estimate of 14 967 861 delivery hospitalizations in the United States, the proportion of individuals eligible for thromboprophylaxis using the RCOG, American College of Chest Physicians, American College of Gynecology and Obstetrics, and American Society for Hematology guidelines were 32.9%, 8.0%, 0.2%, and 0.2%, respectively. Using the RCOG criteria, non-Hispanic Black individuals had the highest proportion of thromboprophylaxis eligibility (39.7%), whereas it was lowest among Hispanic individuals (30.8%). Racial disparities in thromboprophylaxis eligibility were driven by differences in clinical risk factors (38.8% non-Hispanic Black population vs 30.5% Hispanic population) and cesarean section rates (35.9% vs 32.2%), rather than history of VTE (0.3% vs 0.1%), inherited thrombophilia (0.2% vs 0.2%), or sickle cell disease (0.4% vs <0.1%).

CONCLUSION

Non-Hispanic Black individuals were most likely to qualify for postpartum thromboprophylaxis, attributable to clinical risk factors rather than inherited risk factors. An urgent need exists to better understand ethno-racial disparities in thromboprophylaxis use and to equitably address modifiable risk factors for postpartum VTE.

Acute inferior vena cava thromboembolism in pregnancy

A multigravida in her late 20s was diagnosed with inferior vena cava thrombosis (IVCT) and PE at 26 weeks of pregnancy after a routine prenatal care visit. The patient denied any diseases that could cause IVCT, as well as the presence of any symptoms. Progressive thrombocytopenia was diagnosed in the period until the implantation of the inferior vena cava filter (IVCF). Due to a rupture of foetal membranes and chorioamnionitis, labour was induced at 32 weeks of pregnancy. The IVCF remained in place and anticoagulants were continued through the postpartum period for up to 6 months.

The ART of Thromboprophylaxis in the Prevention of Gestational Venous Thromboembolism

Assisted reproductive techniques (ART) allow infertile couples to conceive. Use of hormones to obtain a controlled ovarian stimulation and an adequate growth of the endometrium preparatory for embryo implantation are not riskless. Among others, thrombotic events can occur during the ovulation induction or pregnancy following ART. As the number of women approaching ART to conceive is steadily increasing, the issue of thrombotic risk in this setting is relevant. Data on the weight of each risk factor and on potential benefit of thromboprophylaxis are largely lacking. In this review, we discuss risk of venous thromboembolism during pregnancy following ART, with a focus on general (i.e.: age, body mass index, thrombophilia, bed rest, transfusions) and ART-specific (i.e., polycystic ovarian syndrome, ovarian hyperstimulation syndrome) risk factors. We also attempt to provide some suggestions to guide clinical practice, based on available data and studies performed outside ART.

Predictors of pregnancy-associated venous thromboembolism: A case-control study

Background

Venous thromboembolism (VTE), manifesting as pulmonary embolism (PE) or deep vein thrombosis (DVT), is the most common cause of morbidity and death during pregnancy and the postpartum period. We conducted this study to describe the predictors of pregnancy-associated VTE (DVT and PE).

Methods

A case-control study was conducted at a tertiary care center in Riyadh. A total of 380 patients were included in this study, 180 of whom were diagnosed with pregnancy-associated thrombosis and 200 of them showed no VTE. Demographic data and data on risk factors of VTE were collected by reviewing the medical charts and the risk assessment tool of the Royal College of Obstetricians and Gynecologists, respectively. The main outcome measures were VTE, manifesting as PE or DVT.

Results

The following factors were identified as the predictors of VTE through multivariate analysis: family history [Odds ratio (OR) = 50.47, 95% Confidence Interval (CI): 6.78–375.64, P < 0.0001)], thrombophilia (OR = 21.99, 95% CI: 2.83–170.63, P = 0.003), and presence of gross varicose veins (OR = 17.15, 95% CI: 3.93–74.87, P < 0.0001).

Conclusions

The findings of this study showed that family history, thrombophilia, and the presence of gross varicose veins were risk factors for VTE, exceeding other transient risk factors. Hence, prophylaxis is highly recommended for those women who present with any of these factors.

Prophylactic Dose of Dalteparin in Pregnant Women With History of Venous Thromboembolisms and/or Thrombophilia: Real-World Data

Women with a history of venous thromboembolisms (VTEs) and/or thrombophilia are at increased risk of VTE during pregnancy. We analysed our cohort of such women who were treated with a prophylactic doses of dalteparin. 152 pregnant women with 179 pregnancies were classified into 3 groups: (1) previous VTE without thrombophilia (122 pregnancies); (2) previous VTE with thrombophilia (26 pregnancies) and (3) thrombophilia only (31 pregnancies). They were treated with prophylactic dalteparin in the prepartum and postpartum periods or only in the postpartum period. Occurrences of symptomatic VTE and bleeding episodes were followed, as well as dalteparin discontinuation and anti-Xa activity. Symptomatic deep vein thrombosis occurred in 4 women (2.2%) with 2 episodes in group 1 (in the postpartum period) and 2 episodes in group 2 (one in the prepartum and another in the postpartum period). Seven episodes (3.9%) of minor bleeding occurred. Dalteparin was not stopped in any women. Anti-Xa levels were within the prophylactic range. Our real-world data show a low incidence of thrombosis and minor bleeding in pregnant women treated with prophylactic dalteparin. The incidence of recurrent VTE was lower than that reported in women with similar risk, but without prophylactic anticoagulation.