Long-term outcome of deep venous thrombosis during pregnancy treated with unfractionated heparin or low molecular weight heparin

Optimizing obstetric venous thromboembolism protocol adherence: The experience of a hospital system

The purpose of this review is to explore the role of hospital systems in reliably providing high quality obstetric venous thromboembolism (VTE) prophylaxis focusing on the example of the Kaiser Permanente Southern California hospital system. While providers ultimately administer thromboprophylaxis on a patient-by-patient basis, hospital-level protocols, practices, and resources may be the most important determinants of whether a patient receives appropriate care. In comparison to the complex maternal and fetal emergencies that obstetricians are routinely called on to manage, VTE prophylaxis can often be simplified and integrated into the workflow, making decision-making time efficient and straightforward for the provider. Not having protocols (i.e. the provider being on their own) is associated with desired management occurring in only 40% of cases. Enhanced VTE protocols with complementary strategies to encourage use and identification of oversights addressed in real time can result in appropriate care in >90% of cases.

Pregnancy and venous thromboembolism

PURPOSE OF REVIEW

This review provides a concise and complete overview of diagnostic work-up and treatment of venous thromboembolism in pregnancy, with attention to recent research developments and recent applicable guidelines. This may be useful for all the players of the multidisciplinary interaction needed in this disease management, namely cardiologists and gynecological/obstetric teams.

RECENT FINDINGS

Venous thromboembolism is, in the developed world, a major cause of maternal morbidity and mortality during pregnancy or early after delivery, with a reported incidence ranging from 0.49 to 2.0 events per 1000 deliveries. It is a particularly challenging issue and there is no common consensus on the major themes of this condition. Diagnostic options, prophylaxis and management, in the antenatal, childbirth and postnatal periods, are carefully analyzed in the light of the most recent published data. Besides, old and recent knowledge must be seen through the clinician's skilled and watchful eyes, deciding on a case-to-case and actively contributing in reducing pregnancy-related morbidity.

SUMMARY

Although there is an ongoing debate on various aspects of this condition and there is a paucity of high-quality studies, this review attempts to simplify the complex aspects of joining safety and efficacy in diagnosing and treating a possible two-people life-threatening disease.

Association between thrombophilia and the post-thrombotic syndrome: a systematic review and meta-analysis

BACKGROUND

The postthrombotic syndrome (PTS) is a frequent chronic complication of deep vein thrombosis (DVT), occurring in 20-40% of patients. Identifying risk factors for PTS may be useful to provide patients with prognostic information and target prevention strategies.

OBJECTIVE

To conduct a systematic review to assess whether, among patients with DVT, inherited and acquired thrombophilias are associated with a risk of PTS.

METHODS

We searched the electronic databases PubMed, EMBASE, Scopus, and Web of Science for studies published from 1990 to 2013 that assessed any thrombophilia in adult DVT patients and its association with the development of PTS. We calculated odds ratios and 95% confidence intervals for PTS according to the presence of thrombophilia. Meta-analysis was performed using the random-effects model.

RESULTS

Sixteen studies were included: 13 assessed factor V Leiden (FVL), 10 assessed prothrombin mutation, five assessed protein S and C deficiencies, three assessed antithrombin deficiency, four assessed elevated FVIII levels, and six assessed antiphospholipid antibodies. None of the meta-analyses identified any thrombophilia to be predictive of PTS. Both FVL and prothrombin mutation appeared protective among studies including patients with both first and recurrent DVT and studies in which more than 50% of patients had an unprovoked DVT.

CONCLUSIONS

Our meta-analysis did not demonstrate a significant association between any of the thrombophilias assessed and the risk of PTS in DVT patients. Other biomarkers in the pathophysiological pathway may be more predictive of PTS.

Venous thromboembolism in pregnancy

Low molecular weight heparins (LMWHs) appear to be as safe and effective as unfractionated heparin (UFH) for venous thromboembolic disease (VTED) treatment or prophylaxis during pregnancy. Experience with other parenteral anticoagulant drugs is very limited, and no alternative oral anticoagulants are available to date. In addition to cost, challenges of long-term LMWH use during pregnancy that have not been addressed by controlled clinical trials include a) ideal dosing as pregnancy advances, b) the need for LMWH monitoring by anti-Xa activity levels, and c) ideal therapeutic management as the delivery date nears. Because therapeutic-intensity anticoagulation during pregnancy is challenging, many practitioners favor a more "aggressive" approach toward VTED prophylaxis in women perceived to be at very high risk of thrombosis during pregnancy. Best evidence to date suggests that most women with thrombophilias or with a previous "situational" VTED event probably do not require VTED prophylaxis antepartum, but postpartum anticoagulation prophylaxis is recommended for a few weeks. For those with a history of previous idiopathic VTED or VTED associated with "hormonal challenge" (such as with contraceptive use or previous pregnancy), prophylaxis beginning antepartum may be considered and discussed with the patient. Selected cases of "severe" thrombophilia are probably best managed by initiation of pharmacologic VTED prophylaxis antepartum. However, it must be emphasized that data from prospective controlled clinical trials are lacking.

Venous thromboembolism in pregnancy

The purpose of this review is to summarize the epidemiology of venous thromboembolism (VTE) in pregnancy and describe strategies used to prevent and treat it. The main reason for the increased risk of VTE in pregnancy is hypercoagulability. The hypercoagulability of pregnancy, which has likely evolved to protect women from the bleeding challenges of miscarriage and childbirth, is present as early as the first trimester and so is the increased risk of VTE. Other risk factors include a history of thrombosis, inherited and acquired thrombophilia, certain medical conditions, and complications of pregnancy and childbirth. Candidates for anticoagulation are women with a current thrombosis, a history of thrombosis, thrombophilia, and a history of poor pregnancy outcome, or postpartum risk factors for VTE. For fetal reasons, the preferred agents for anticoagulation in pregnancy are heparins. There are no large trials of anticoagulants in pregnancy and recommendations are based on case series and the opinion of experts. Nonetheless, anticoagulants are believed to improve the outcome of pregnancy for women who have or have had VTE.

Pregnancy-associated thrombosis

The main reason for the increased risk of thromboembolism in pregnancy is hypercoagulability, which has likely evolved to protect women from the bleeding challenges of miscarriage and childbirth. Women are at a 4- to 5-fold increased risk of thromboembolism during pregnancy and the postpartum period compared with when they are not pregnant. Eighty percent of the thromboembolic events in pregnancy are venous, with an incidence of 0.49 to 1.72 per 1000 pregnancies. Risk factors include a history of thrombosis, inherited and acquired thrombophilia, maternal age greater than 35, certain medical conditions, and various complications of pregnancy and childbirth. Despite the increased risk of venous thromboembolism (VTE) during pregnancy and the postpartum period, most women do not require anticoagulation. Candidates include women with current VTE, a history of VTE, thrombophilia and a history of poor pregnancy outcome, or risk factors for postpartum VTE. The intensity of the anticoagulation will depend on the indication and the monitoring will depend on the intensity. At the time of delivery, anticoagulation should be manipulated to reduce the risk of bleeding complications while minimizing the risk of thrombosis. There are no large trials of anticoagulants in pregnancy, and recommendations are based on case series, extrapolations from nonpregnant patients and the opinion of experts. Nonetheless, anticoagulants are believed to improve the outcome of pregnancy for women who have, or have had, VTE.

A descriptive evaluation of unfractionated heparin use during pregnancy

BACKGROUND

The mainstay of oral anticoagulant therapy, warfarin sodium, crosses the placenta during pregnancy and may cause fetal complications. Unfractionated heparin (UFH) and low-molecular-weight heparin (LMWH) do not cross the placenta and have demonstrated utility in the prevention and treatment of thrombosis during pregnancy.

OBJECTIVES

The purpose of this study was to review treatment strategy, indication, and maternal and fetal outcomes in anticoagulated pregnancies at Kaiser Permanente Colorado.

PATIENTS/METHODS

We identified 103 pregnancies in 93 mothers prescribed an anticoagulant during a pregnancy occurring between January 1, 1998 and March 31, 2005.

RESULTS

The majority of patients were treated with UFH (89.3%). Indications for anticoagulation included venous thromboembolism (VTE) prophylaxis (53.4%), history of pregnancy loss (29.1%), acute VTE (16.5%), and history of cerebral vascular accident (CVA) (1.0%). There were no maternal deaths. Fetal demise occurred in 8 pregnancies (7.8%) at a median 14 weeks gestation (range 7-22 weeks). No fetal demise occurred in pregnancies treated for acute VTE or history of CVA. There were two occurrences of pulmonary embolism (1.9%) and two hemorrhagic events requiring transfusion (1.9%).

CONCLUSIONS

Maternal and fetal adverse events were infrequent in our population of anticoagulated pregnancies. UFH remains a viable option among more expensive LMWH products.

Prevention and management of venous thromboembolism in pregnancy

Normal pregnancy is accompanied by an increase in clotting factors. The resulting hypercoagulable state has likely evolved to protect women from hemorrhage at the time of miscarriage and childbirth. During pregnancy, women are 4 times more likely to suffer from venous thromboembolism (VTE) compared with when they are not pregnant. Relative to pregnancy, the risk postpartum is even higher. The incidence of VTE is approximately 2 per 1,000 births, and VTE accounts for 1 death per 100,000 births, or approximately 10% of all maternal deaths. The most important risk factors during pregnancy are thrombophilia and a history of thrombosis. A history of thrombosis increases the risk for VTE to 2% to 12%. Thrombophilia increases not only the risk for maternal thrombosis but also the risk of poor pregnancy outcome. Despite the increased risk for thrombosis during pregnancy and the postpartum period, most women do not require anticoagulation. Those who do require anticoagulation include women with current VTE, women on lifelong anticoagulation, and many women with thrombophilia or a history of thrombosis. Recommended options for anticoagulation in pregnancy are limited to heparins, which do not cross the placenta. Low-molecular-weight heparin (LMWH) is preferred over unfractionated heparin because LMWH has a longer half-life and is presumed to have fewer side effects. The longer half-life is a disadvantage around the time of delivery, when unfractionated heparin, with its shorter half-life, is easier to manage. For women who develop or are at high risk for heparin-induced thrombocytopenia or severe cutaneous reactions, fondaparinux is probably the agent of choice. Women who do not require lifelong anticoagulation, but require anticoagulation during pregnancy, will still require anticoagulation for the first 6 weeks postpartum.

Cost-effectiveness of prophylactic low molecular weight heparin in pregnant women with a prior history of venous thromboembolism

PURPOSE

Women with a history of prior venous thromboembolism have an increased risk for recurrence during pregnancy. Although thromboprophylaxis reduces this risk, recent evidence suggests that, in many cases, prophylaxis can be safely withheld because the estimated recurrence risk is very low. The balance of risks and benefits in women with different recurrence risks has not been examined.

METHODS

We developed a Markov state transition decision analytic model to compare prophylactic low molecular weight heparin to expectant management for pregnant women with a single prior venous thromboembolism. A lifetime time horizon and societal perspective were assumed. Input data were obtained by literature review. Outcomes were expressed as U.S. dollars per quality-adjusted life-year (QALY).

RESULTS

For "low-risk" women with a prior venous thromboembolism associated with a transient risk factor and no known thrombophilic condition (recurrence risk 0.5%), expectant management was both more effective and less costly than prophylaxis. For "high-risk" women with prior idiopathic venous thromboembolism or known thrombophilic condition (recurrence risk 5.9%), prophylaxis was associated with a reasonable cost-effectiveness ratio (USD 38,700 per QALY) given a risk of bleeding complications <1.0% (base case 0.5%).

CONCLUSION

For low-risk women with prior venous thromboembolism, expectant management during pregnancy leads to better outcomes than administration of prophylactic low molecular weight heparin. For high-risk women, antepartum thromboprophylaxis is a cost-effective use of resources.