DEEP VENOUS THROMBOSIS AND PULMONARY EMBOLISM IN PREGNANCY

Pregnancy and thrombophilia

The physiological changes that occur during pregnancy create a hypercoagulable milieu. This hypercoagulable state is thought to be protective, especially at the time of labor, preventing excessive hemorrhage. The presence of hereditary or acquired causes of thrombophilia during pregnancy tilts the balance in favor of unwanted venous thromboembolism and adverse pregnancy outcomes due to vascular uteroplacental insufficiency. These adverse pregnancy outcomes include recurrent pregnancy losses, intrauterine fetal death, intrauterine growth retardation, preeclampsia and placental abruption. Much of the current data with regards to the association of the different thrombophilias and pregnancy-related complications are based on retrospectively designed studies. This lack of randomization, in-homogeneity of patient populations, varying case definitions, selection biases and inadequately matched control populations, have given rise to conflicting data with regard to screening for, and treatment of, pregnant women with suspected thrombophilias. The limited data that we have support the use of anticoagulant drugs for the prevention of pregnancy-related complications in the setting of thrombophilia. Heparin and low-molecular-weight heparins are the anticoagulant drugs of choice as they do not cross the placental barrier and, hence, do not cause fetal anticoagulation or teratogenicity. Warfarin can be used from the 12th week of gestation onwards but is preferably reserved for the postpartum period.

Low molecular weight heparins: a guide to their optimum use in pregnancy

The incidence of pulmonary embolism (PE) and venous thromboembolism (VTE) is higher in pregnant patients than in non-pregnant patients. The incidence of thrombosis in all pregnancies is reported to be between 0.05 and 1%, and an incidence as high as 3% may be present in women after caesarean section. Anticoagulant medication is prescribed during pregnancy in patients presenting with VTE, thrombophilia abnormalities, or a history of PE or VTE. Since unfractionated heparin (UH) does not cross the placental barrier, it has become the gold standard anticoagulant therapy during pregnancy. Oral anticoagulants may also be prescribed during the second trimester but they cross the placental barrier. Low molecular weight heparins (LMWH) are effective, easy to use and have good safety profiles. The practical conditions of use have yet to be validated for pregnancy settings. In the absence of an approved indication, LMWH use during pregnancy is therefore the responsibility of the practitioner. However, several studies on LMWH as prophylaxis for PE or VTE have shown that such products are effective with good safety. Moreover, LMWH use is associated with reduced frequencies of thrombocytopenia and osteoporosis compared with UH use. Very few studies on LMWH use for the treatment of PE or VTE during pregnancy have been published, but the safety of LMWH use in this setting appears to be good. The review of the use of LMWH in pregnancy settings includes recommendations on the practical conditions of use. In the absence of large-scale, randomised, double-blind trials in such settings (which are needed), we propose the use of LMWH as prophylaxis for PE and VTE during pregnancy, but not for the treatment of these conditions. In prophylaxis settings, dalteparin sodium and enoxaparin sodium have been the most widely studied LMWH and we believe that priority should therefore be given to those products. Pending approval of LMWH for use in pregnancy, the use of LMWH off-label is the practitioner's responsibility.

A case report of warfarin resistance due to azathioprine and review of the literature

A 32-year-old woman with a history of deep vein thrombosis (DVT), steroid-dependent ulcerative colitis, and osteoporosis was prescribed azathioprine for a steroid-sparing effect. Stable, therapeutic international normalized ratios (INRs) were obtained with warfarin 35 mg/week during a 6-week postpartum course to treat an initial DVT. Ten days after completing warfarin therapy, azathioprine was begun. A recurrent DVT occurred 9 days later, and an increase in warfarin dosage to 120 mg/week was necessary to achieve an INR of 2.0-3.0. The patient denied changes in warfarin adherence, dietary vitamin K intake, or medical conditions. The addition of azathioprine was the only change in her regimen. Review of the literature found only limited reports of an interaction between warfarin and azathioprine, with increases in warfarin requirements of 3-4 times. Careful monitoring and caution are recommended when administering these two drugs concomitantly.

Presentation of venous thromboembolism during pregnancy

OBJECTIVE

We sought to characterize the presentation, recurrence, and outcome of venous thromboembolism during pregnancy.

STUDY DESIGN

We performed a 12-year, single-center, retrospective review of 38 patients with venous thromboembolism during pregnancy. The independent variables were subjected to univariate analysis (unpaired t test for normally distributed continuous variables and Fisher exact test for discrete variables). P <.05 was considered significant.

RESULTS

There was no significant difference for the following variables according to time of presentation (antepartum vs post partum): gestational age at delivery (37.4 +/- 6.6 wk vs 38.1 +/- 2.4 wk; P =.7), birth weight (3257 +/- 458 g vs 3093 +/- 719 g; P =.3), and mode of delivery (2 vs 4 cesarean deliveries; P =.15). There were 2 maternal deaths. All 3 women with antepartum recurrent venous thromboembolism (despite heparin prophylaxis) had findings of protein C deficiency, protein S deficiency, and lupus anticoagulant-anticardiolipin antibody, respectively.

CONCLUSION

The gestational age at presentation appears more equally distributed throughout gestation than previously reported. Notwithstanding limited numbers, the recurrence of venous thromboembolism despite use of prophylactic heparin therapy suggests the need to reexamine the current recommendations for heparin dosing.

Medical problems during pregnancy

Dramatic physiologic changes are part of normal human pregnancy. The physiologic alterations of pregnancy have the potential to affect chronic diseases, to unmask subclinical conditions, or to alter the presentation and course of newly acquired illnesses. An update in selected topics of obstetric medicine follows, focusing on clinical entities in which there have been significant advances in diagnosis or management. Additionally, reviews of selected medical disorders, such as HIV infection and asthma, that are rising in incidence in women of reproductive age are included.

Current concepts of anticoagulant therapy in pregnancy

The optimal use of anticoagulants during pregnancy will continue to be controversial until appropriate randomized controlled and prospective trials with adequate sample sizes are completed. The relative low frequency of thromboembolic events, the concerns about maternal and fetal safety of both treatment and withholding treatment, and the reservations about prospectively enrolling pregnant women in treatment trials has sadly dissuaded the appropriate study of this life-threatening condition. North American trials that enroll pregnant women to evaluate the efficacy of LMWH are of preeminent importance owing to their superior bioavailability, ease in dosing, longer half-life, and side effect profile. Similarly, trials evaluating the optimal management of women of childbearing age with valvular disease are critical to reduce the considerable maternal and fetal morbidity and mortality associated with these pregnancies. Such definitive studies will need to be multicenter in design and it is hoped that the National Institutes of Health initiative to enroll pregnant women in clinical trials will at last be realized in the near future.

Deep vein thrombosis in pregnancy and the puerperium: a comprehensive review

Although uncommon during pregnancy and the postpartum period, deep vein thrombosis (DVT) and its sequela, pulmonary thromboembolism, remain leading sources of maternal mortality and morbidity. The majority of literature concerning DVT in pregnancy and the postpartum period exists in the medical journals, with only a small amount in nursing journals. This article provides the nursing community a comprehensive review of literature concerning the incidence of both DVT and pulmonary embolism in pregnancy and the postpartum period, identification of risk factors, the effectiveness of available screening and diagnostic tools, and finally, options for treatment and prophylaxis.

Thrombolytic and endovascular treatment of peripartum iliac vein thrombosis: a case report

This case report details the multidisciplinary treatment of peripartum left iliac vein thrombosis using percutaneous catheter-directed urokinase thrombolysis and balloon thromboplasty. Enhanced chances for long-term patency and the normalization of venous function make these minimally invasive procedures accepted options for the treatment of iliofemoral deep venous thrombosis in selected peripartum patients.

Thromboembolic prophylaxis with low molecular weight heparin during pregnancy

OBJECTIVE

The objective of this study was to show that low molecular weight heparin (LMWH) can be used in preventing veno-pulmonary thromboembolic diseases in pregnancy.

METHODS

Twenty-four women carrying 27 pregnancies with known risk of veno-pulmonary thromboembolic diseases in pregnancy were prophylactically treated with LMWH (dalteparin) during part of their pregnancy. Our therapeutic target was a plasma concentration of 0.20-0.50 anti-Xa U/ml measured 2-6 h after subcutaneous administration of LMWH into the abdominal wall. To obtain this anti-Xa activity the patients were given total doses of 2500-10,000 anti-Xa U daily. Monitoring of anti-Xa activity in patients receiving < or = 5000 U/day was not necessary.

RESULTS

Twelve out of the 24 women received LMWH at the time of delivery. Our biochemical assay could not show the presence of anti-Xa activity in the blood samples from the babies although it was possible to show anti-Xa activity in their mothers. In three out of 24 women, blood samples showed activation of coagulation. These patients were changed to the vitamin K antagonist phenindione.

CONCLUSIONS

None of the treated women showed any clinical or paraclinical signs of thromboembolic diseases during pregnancy or 6 weeks postpartum. All the babies were born healthy. None of the women had any side effects due to the treatment.