Prevention and management of venous thromboembolism in pregnancy

Variations in postdelivery infection and thrombosis by hospital teaching status

OBJECTIVE

Using a population-based cohort, we examined hospital-level variation overall and by teaching status in 2 maternal outcomes, postpartum infections, and thrombosis.

STUDY DESIGN

Linked birth certificate and hospital admission records for mother and infant were collected on all deliveries in Pennsylvania and California from 2004 through 2005. A risk adjustment model was created using maternal and fetal comorbidities identified by International Classification of Diseases-9 codes. Hospitals were classified as teaching (TH) or nonteaching hospitals (NTH) based on the presence of obstetrics and gynecology residents. Rates of infections and thrombosis were evaluated overall and by hospital teaching status.

RESULTS

A total of 939,871 patients were evaluated from 402 hospitals (369 NTH and 33 TH). The unadjusted infection and venous thromboembolic events (VTE) rates were higher in TH vs NTH (infection: 2.04% vs 1.07%, P < .001; VTE: 1.04% vs 0.08%, P < .001). There was variation in the rates of these complications across hospitals, with the adjusted observed/expected ratio rates for infection and thrombosis for each hospital, ranging from 0-5.2 and 0-8.6, respectively.

CONCLUSION

There is substantial variation in infection and thrombosis rates among hospitals both overall and by teaching status, suggesting that these 2 outcomes may be useful measures of inpatient obstetric quality.

Does asymptomatic carriage of FV Leiden and FII prothrombin mutations in heterozygous configuration pose an increased risk of thrombembolic complications in the course of pregnancy, labor and puerperium?

OBJECTIVE

To evaluate the course of pregnancy and puerperium in asymptomatic carriers of FV Leiden and FII prothrombin mutation in heterozygous configuration in terms of risk of thrombembolic disease (TED) and late pregnancy complications. To evaluate whether global prophylactic LMWH administration during pregnancy benefits these women.

METHODS

We monitored the incidence of thrombembolic events and severe late pregnancy complications in 473 asymptomatic carriers of FV Leiden and FII prothrombin mutation in heterozygous configuration. In 253 women, preventive LMWH application was introduced already during pregnancy. In 220 women, the application of LMWH was commenced as late as on the delivery day. In both groups application of LMWH continued during the puerperium.

RESULTS

The incidence of TED in the whole group of carriers of thrombophylic mutations accounted for 0.19%. The incidence of severe late pregnancy complications was low - 2.5% compared with general population of pregnant women (6.4%).

CONCLUSIONS

No direct causal relationship was established between asymptomatic carriage of Leiden and prothrombin mutation in heterozygous configuration and the occurrence of severe late pregnancy complications. There was no benefit from general LMWH prophylaxis started as early as pregnancy in these women and thus we consider it unnecessary.

Risk of placenta-mediated pregnancy complications or pregnancy-related VTE in VTE-asymptomatic families of probands with VTE and heterozygosity for factor V Leiden or G20210 prothrombin mutation

BACKGROUND

Few studies have evaluated the risk of pregnancy-related adverse events in asymptomatic relatives of probands for VTE and factor V Leiden or the G20210A variant. The antepartum management of this population ranges from antepartum anticoagulation therapy to clinical surveillance.

OBJECTIVE

To evaluate the risk of placenta-mediated pregnancy complications and pregnancy-related VTE in VTE-asymptomatic families of probands with VTE and who are heterozygous carriers of either factor V Leiden or PT-G20210A mutation.

METHODS

One hundred and fifty-eight relatives, who had 415 pregnancies, were retrospectively evaluated. Odds ratios and 95% confidence intervals were calculated to compare pregnancy outcomes between women with and without thrombophilia.

RESULTS

In the factor V Leiden group, 22 placenta-mediated pregnancy events of 152 pregnancies (14.4%) were reported, compared with 25 adverse events of 172 pregnancies in the G20210A prothrombin group (14.5%) and 13 adverse events of 91 pregnancies in the non-carrier group (14.2%). Carriers of factor V Leiden or G20210A prothrombin were not associated with a higher risk of pregnancy-adverse outcomes compared with non-carriers: OR 1.02 (95% CI, 0.40-2.25) and 1.25 (95% CI, 0.48-3.24), respectively. Four episodes of pregnancy-associated VTE of 415 pregnancies (0.96%) were recorded. Two episodes of VTE in the G20210A group, one in the factor V Leiden group, and one episode in the non-carrier group were noted.

CONCLUSIONS

In VTE-asymptomatic relatives of probands with VTE, the presence of factor V Leiden or the G20210A prothrombin mutation in heterozygosis should not lead to a decision to instigate antepartum prophylaxis.

Early diagnosis of iliofemoral DVT in pregnancy in the emergency department

The case of a 26-year-old woman who was 23 weeks pregnant is described; the patient presented, on a weekend, to the emergency department (ED) with left groin pain. There were few clinical signs of deep venous thrombosis (DVT) but ED ultrasound (US) showed a left external iliac vein thrombus. This is a new technique in the ED. Not only does this case show the importance of using this technique in the ED, but it also shows the importance of correct training in how to examine for thrombus in the external iliac vein in the pregnant patient. The patient was admitted to the hospital and started on low-molecular-weight heparin. A formal radiology department US performed the next week confirmed the diagnosis of DVT.

Feasibility of an easy-to-use risk score in the prevention of venous thromboembolism and placental vascular complications in pregnant women: a prospective cohort of 2736 women

INTRODUCTION

Management of pregnant women at increased risk of venous thromboembolism (VTE) remains complex in the absence of an easy-to-use tool allowing individualised, risk-adapted prophylaxis. Our objective was to assess whether treatment based on risk score is feasible in these women.

MATERIALS AND METHODS

A scoring system for VTE risk in pregnant women was developed, each score being associated with a specific treatment. This system was implemented in a prospective cohort of 2736 consecutive women delivered in our teaching hospital from July 2002 to June 2003. Thromboembolic and obstetrical outcomes during pregnancy and the early post-partum period were recorded.

RESULTS

Treatment based on risk score was implemented in 2685 of the 2736 women included (98.1%). The scoring system identified 2431 women with no risk factor and 305 women (11%) with at least one risk factor. Eight women not at risk (0.3%, [95% CI: 0.1-0.5]) and one at risk (0.4%, [95% CI: 0-1.1]) experienced a VTE. This low event rate precluded estimation of the discriminatory power of the score. However, the benefit of the scoring system was evaluated indirectly by assessing VTE incidence in the 46 women at risk in whom it was not used (15.2%, [95% CI: 4.8-25.6]).

CONCLUSIONS

Our simple scoring system offers an easily implemented procedure for risk-based VTE prophylaxis of pregnant women and the proposed therapeutic strategy appears to be effective and safe in reducing VTE. The discriminatory power of the score is currently being evaluated in a randomized, controlled trial.

Thrombophilia and the Risk for Venous Thromboembolism during Pregnancy, Delivery, and Puerperium

The main inherited thrombophilias (antithrombin deficiency, protein C and S deficiency, FVL, the prothrombin gene variant, and MTHFR C677T homozygotes) have a combined prevalence in Western European populations of 15% to 20%. One or more of these inherited thrombophilias is usually found in approximately 50% of women who have a personal history of VTE. Obstetricians must therefore be aware of the interaction between thrombophilias and the procoagulant state of pregnancy and should have an understanding of additional risk factors that may act synergistically with thrombophilias to induce VTE. Such knowledge combined with the appropriate use of thromboprophylaxis and treatment in women who have objectively confirmed VTE continue to improve maternal and perinatal outcomes.

Cost-effectiveness of Thromboprophylaxis With Intermittent Pneumatic Compression at Cesarean Delivery

OBJECTIVE

To evaluate the cost-effectiveness of thromboprophylaxis at cesarean delivery with intermittent pneumatic compression.

METHODS

A decision tree model using Markov analysis was developed to compare two approaches to perioperative care at the time of cesarean delivery: 1) no use of perioperative thromboprophylaxis and 2) the use of intermittent pneumatic compression for thromboprophylaxis at the time of cesarean delivery. Postcesarean deep venous thrombosis was estimated to occur in 0.7% of patients (75% of whom were asymptomatic), and result in a 9% chance of postthrombotic syndrome. Mechanical prophylaxis was assumed to decrease the risk of deep venous thrombosis by 70% and to cost 120 dollars. Probability of morbidity and mortality of venous thromboembolism as well as anticoagulation and the costs and utilities for different health state were derived from published studies. Sensitivity analysis was performed over a wide range of variable estimates.

RESULTS

Using the assumptions in our base case, routine thromboprophylaxis for cesarean delivery cost 39,545 dollars per quality-adjusted life year. One-way sensitivity analysis revealed that as long as the incidence of postcesarean deep venous thrombosis was at least 0.68%, intermittent pneumatic compression reduced the incidence of deep venous thrombosis by at least 50%, or the cost of intermittent pneumatic compression was less than 180 dollars, the cost-effectiveness of mechanical prophylaxis did not exceed 50,000 dollars per quality-adjusted life year.

CONCLUSION

Mechanical thromboprophylaxis is estimated to be a cost-effective strategy under a wide range of circumstances.

Cardiopulmonary complications of pregnancy

OBJECTIVES

To provide an up-to-date review of the literature on the assessment and management of pulmonary and cardiac conditions that may affect women during pregnancy and the postpartum period.

DESIGN

A review of the current literature was performed.

RESULTS

Pregnancy may be complicated by a variety of pregnancy-specific and other cardiopulmonary complications. Management requires knowledge of the cardiopulmonary physiologic changes occurring in pregnancy, the pregnancy-specific conditions that may occur, and the effect of a fetus on maternal care.

CONCLUSIONS

Admission of the pregnant or postpartum woman to the intensive care unit is uncommon but may require specialized knowledge for successful management.

D-dimer levels during delivery and the postpartum

BACKGROUND

D-dimer (DD) measurement has proved to be very useful to exclude venous thromboembolism (VTE) in outpatients. However, during pregnancy, the progressive increase as well as the interindividual variations of DD means that in this instance they are of poor value to rule out VTE. Only a few studies have reported measurements of DD levels in the postpartum.

OBJECTIVES

To measure DD sequentially in the puerperium in order to determine when DD levels return to values obtained in non-pregnant women and can again be used in the exclusion of VTE.

PATIENTS AND METHODS

After uncomplicated pregnancies, 150 women delivering at term either vaginally (n = 100) or by cesarean section (n = 50) were included. DD levels were measured immediately following delivery and next at days 1, 3, 10, 30 and 45.

RESULTS

There was a marked elevation of DD at delivery, especially when instrumental. All DD measurements were above 500 ng mL(-1) at delivery, at day 1 and at day 3 postpartum. A sharp decrease in DD was observed between day 1 and day 3, followed by a slight increase at day 10. At day 30 and day 45, respectively, 79% and 93% of women in the vaginal delivery group and 70% and 83% in the cesarean group had levels below 500 ng mL(-1). Bleeding, breastfeeding and heparin prophylaxis did not modify DD levels significantly.

CONCLUSION

Using the Vidas DD new assay, our study provides reference intervals for DD in the postpartum period. Using a cut-off at 500 ng mL(-1), DD measurement for ruling out VTE was found to be useful again 4 weeks after delivery.

Genetic thrombophilia

The genetic thrombophilias are an important cause of venous thrombotic events. Much has been learned about the natural history of these disorders, their genetics, and, to a lesser degree, their treatment. This article provides an overview of the genetics of thrombophilia. Specific information on the factor V Leiden mutation;the prothrombin G20210A mutation; and protein C, proteinS, and antithrombin deficiency is reviewed. Current testing and treatment options for the genetic thrombophilias also are discussed.

Pulmonary complications of pregnancy

Pregnancy induces significant physiologic stresses on the pulmonary and cardiovascular systems that may precipitate respiratory compromise. In addition, certain disease states that are unique to the pregnant woman, such as amniotic fluid emboli syndrome, may be associated with respiratory failure. The physiologic changes that affect the pregnant woman are reviewed. Pregnancy-related conditions are discussed as well as how common diseases, such as the acute respiratory distress syndrome, asthma, pneumonia, and AIDS,have to be approached when balancing the needs of the fetus with maternal well-being.

Sex and gender issues and venous thromboembolism

At least 250,000 episodes of VTE leading to hospitalization or death are estimated to occur in the United States each year. A number of clinical and demographic risk factors for VTE are recognized,with the latter including both age and race. Overall,the incidence of VTE does not appear to vary significantly by sex, as evidenced by a lack of consistency in the magnitude and even direction of effect of sex in a variety of epidemiologic studies of varying design. Several studies have shown a higher incidence among women than men during childbearing age. The issue of a gender effect on the natural history of VTE has not been well studied. The main influence of gender on VTE is the relationship between female gender and several well-recognized clinical risk factors for VTE:oral contraceptive use, hormone replacement therapy, estrogen receptor modulator therapy, and pregnancy. Hormonal therapies are associated with a twofold to threefold increase in VTE incidence. Risk is higher with some formulations than others, during initial use, and among women who are obese, smoke, or have one of several forms of heritable thrombophilia. The pregnant state is associated with a threefold to fivefold increase in VTE risk, and thromboembolism is a major cause of peripartum death. Heritable thrombophilias are also important co-determinants of VTE risk in pregnancy. The mechanisms through which pregnancy and hormonal therapies increase VTE risk have not been definitively established, but hormonal effects on levels of coagulation and anticoagulation factors likely play a role. Venous compression and venous injury also contribute to increased risk during pregnancy and the puerperium. Approaches to diagnosis of VTE in the pregnant woman are largely the same as in the nonpregnant patient, but special treatment considerations do apply. Warfarin is embryopathic, particularly between the 6th and 12th weeks of pregnancy, and should be avoided in favor or heparin or low-molecular weight heparin when treatment of the pregnant woman is necessary. Guidelines have been published to assist the clinician in decision making about prophylaxis of pregnant women at increased risk or pregnancy-related or post-partum VTE.