The ‘ART’ of thrombosis: a review of arterial and venous thrombosis in assisted reproductive technology

Venous thromboembolism in women: a specific reproductive health risk

BACKGROUND Venous thromboembolism (VTE) is a specific reproductive health risk for women. METHODS Searches were performed in Medline and other databases. The selection criteria were high-quality studies and studies relevant to clinical reproductive medicine. Summaries were presented and discussed by the European Society of Human Reproduction and Embryology Workshop Group. RESULTS VTE is a multifactorial disease with a baseline annual incidence around 50 per 100 000 at 25 years and 120 per 100 000 at age 50. Its major complication is pulmonary embolism, causing death in 1-2% of patients. Higher VTE risk is associated with an inherited thrombophilia in men and women. Changes in the coagulation system and in the risk of clinical VTE in women also occur during pregnancy, with the use of reproductive hormones and as a consequence of ovarian stimulation when hyperstimulation syndrome and conception occur together. In pregnancy, the risk of VTE is increased ~5-fold, while the use of combined hormonal contraception (CHC) doubles the risk and this relative risk is higher with the more recent pills containing desogestrel, gestodene and drospirenone when compared with those with levonorgestrel. Similarly, hormone replacement therapy (HRT) increases the VTE risk 2- to 4-fold. There is a synergistic effect between thrombophilia and the various reproductive risks. Prevention of VTE during pregnancy should be offered to women with specific risk factors. In women who are at high risk, CHC and HRT should be avoided. CONCLUSIONS Clinicians managing pregnancy or treating women for infertility or prescribing CHC and HRT should be aware of the increased risks of VTE and the need to take a careful medical history to identify additional co-existing risks, and should be able to diagnose VTE and know how to approach its prevention.

Incidence of pulmonary and venous thromboembolism in pregnancies after in vitro fertilisation: cross sectional study

OBJECTIVE

To estimate the risk of pulmonary embolism and venous thromboembolism in pregnant women after in vitro fertilisation.

DESIGN

Cross sectional study.

SETTING

Sweden.

PARTICIPANTS

23,498 women who had given birth after in vitro fertilisation between 1990 and 2008 and 116,960 individually matched women with natural pregnancies.

MAIN OUTCOME MEASURES

Risk of pulmonary embolism and venous thromboembolism (identified by linkage to the Swedish national patient register) during the whole pregnancy and by trimester.

RESULTS

Venous thromboembolism occurred in 4.2/1000 women (n=99) after in vitro fertilisation compared with 2.5/1000 (n=291) in women with natural pregnancies (hazard ratio 1.77, 95% confidence interval 1.41 to 2.23). The risk of venous thromboembolism was increased during the whole pregnancy (P<0.001) and differed between the trimesters (P=0.002). The risk was particularly increased during the first trimester, at 1.5/1000 after in vitro fertilisation versus 0.3/1000 (hazard ratio 4.22, 2.46 to 7.26). The proportion of women experiencing pulmonary embolism during the first trimester was 3.0/10,000 after in vitro fertilisation versus 0.4/10,000 (hazard ratio 6.97, 2.21 to 21.96).

CONCLUSIONS

In vitro fertilisation is associated with an increased risk of pulmonary embolism and venous thromboembolism during the first trimester. The risk of pulmonary embolism is low in absolute terms but because the condition is a leading cause of maternal mortality and clinical suspicion is critical for diagnosis, an awareness of this risk is important.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01524393.

A case of ovarian hyperstimulation syndrome following a spontaneous complete hydatidiform molar pregnancy

INTRODUCTION

To present a rare case of ovarian hyperstimulation syndrome (OHSS) following a spontaneous complete hydatidiform molar (CHM) pregnancy.

CASE

A 38-year-old woman underwent vacuum curettage for a CHM pregnancy. Seven days later, she was admitted to our hospital with the symptoms of OHSS. Transvaginal ultrasonography demonstrated enlarged multicystic ovaries, marked ascites and large pleural effusions that required abdominocentesis and thoracocentesis, respectively. She was treated with intravenous fluid, exogenous colloid supplementation, prophylaxis for deep vein thrombosis, and drainage of the ascites and bilateral pleural effusions. She recovered by day 14 of admission.

CONCLUSION

OHSS may develop in older women who undergo treatment for CHM pregnancies. Serious complications may develop rapidly and therefore the prompt diagnosis of OHSS is very important.

Acute portal vein thrombosis complicating in vitro fertilization

OBJECTIVE

To describe a case of acute portal vein thrombosis after IVF treatment.

DESIGN

Case report.

SETTING

University teaching hospital.

PATIENT(S)

A 39-year-old woman experienced worsening, right upper quadrant pain several days after oocyte retrieval; ET was withheld. Imaging studies revealed acute portal vein thrombosis with extension into the splenic and superior mesenteric veins.

INTERVENTION(S)

Therapeutic anticoagulation; no ET was performed.

MAIN OUTCOME MEASURE(S)

Improvement in symptoms, accurate diagnosis of condition.

RESULT(S)

Decreased size of portal vein thrombosis and partial vessel recanalization.

CONCLUSION(S)

Thromboembolic events are a rare complication of assisted reproductive technology (ART). In women who present with upper abdominal pain during ART, portal vein thrombosis should be considered in the differential diagnosis.

Low-dose lisinopril in normotensive men with idiopathic oligospermia and infertility: a 5-year randomized, controlled, crossover pilot study

The outcomes of drug treatment for male infertility remain conjectural, with controversial study results. Our pilot study employed a randomized, placebo-controlled, crossover methodology with intention-to-treat analysis. Thirty-three men with idiopathic oligospermia were randomized to start either daily oral lisinopril 2.5 mg (n = 17) or daily oral placebo (n = 16). Lisinopril was found to cause a normalization of seminal parameters in 53.6% of the participants. Although the mean ejaculate volume was unchanged (P ≥ 0.093), the total sperm cell count and the percentage of motile sperm cells increased (P ≤ 0.03 and P < 0.001, respectively), whereas the percentage of sperm cells with abnormal morphology decreased (P ≤ 0.04). The pregnancy rate was 48.5%, and there was no serious adverse drug event. It is concluded, albeit cautiously, that prolonged treatment with 2.5 mg/day of oral lisinopril may be well tolerated in normotensive men with idiopathic oligospermia, may improve sperm quantity and quality, and may enhance fertility in approximately half of those treated.

No evidence that assisted reproduction increases the risk of thrombosis: a Danish national cohort study

BACKGROUND

Case reports have reported venous and arterial thromboses in women undergoing assisted reproduction. No large systematic studies on the risk of thrombosis have been published. The objective of our study was to investigate whether the risk of thrombosis is increased in women undergoing assisted reproduction.

METHODS

A national register-based cohort study was conducted on all women undergoing IVF or ICSI treatment in Denmark from 1994 to 2005. Data were obtained from the National Patient Registry and the IVF Registry. Women with prior malignant or cardiovascular disease were excluded. Thrombosis occurring within the first 6 and 12 months after assisted reproduction was considered potentially related to the treatment. Thromboses during pregnancy as well as the pregnancy-related diagnoses were excluded from the statistical analysis. The incidence rates of venous and arterial thromboses were compared with previously published estimates of the risk of thrombosis among young Danish women.

RESULTS

We analyzed 30 884 Danish women undergoing 75 141 treatments from 1994 to 2005. The mean age of the women at first treatment was 32.3 years. The delivery rate per cycle was 22%. The incidence rate ratio, with 95% confidence interval (CI), of venous thrombosis within 6 months was 0.95 (CI: 0.38-1.95). The incidence rate ratio of arterial thrombosis within 6 months was 0.36 (CI: 0.04-1.30).

CONCLUSIONS

Our study showed no evidence that assisted reproduction increases the risk of thrombosis.

VTE, thrombophilia, antithrombotic therapy, and pregnancy: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

The use of anticoagulant therapy during pregnancy is challenging because of the potential for both fetal and maternal complications. This guideline focuses on the management of VTE and thrombophilia as well as the use of antithrombotic agents during pregnancy.

METHODS

The methods of this guideline follow the Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines in this supplement.

RESULTS

We recommend low-molecular-weight heparin for the prevention and treatment of VTE in pregnant women instead of unfractionated heparin (Grade 1B). For pregnant women with acute VTE, we suggest that anticoagulants be continued for at least 6 weeks postpartum (for a minimum duration of therapy of 3 months) compared with shorter durations of treatment (Grade 2C). For women who fulfill the laboratory criteria for antiphospholipid antibody (APLA) syndrome and meet the clinical APLA criteria based on a history of three or more pregnancy losses, we recommend antepartum administration of prophylactic or intermediate-dose unfractionated heparin or prophylactic low-molecular-weight heparin combined with low-dose aspirin (75-100 mg/d) over no treatment (Grade 1B). For women with inherited thrombophilia and a history of pregnancy complications, we suggest not to use antithrombotic prophylaxis (Grade 2C). For women with two or more miscarriages but without APLA or thrombophilia, we recommend against antithrombotic prophylaxis (Grade 1B).

CONCLUSIONS

Most recommendations in this guideline are based on observational studies and extrapolation from other populations. There is an urgent need for appropriately designed studies in this population.

[Thrombosis of the jugular vein during pregnancy]

Thrombosis of the jugular vein is a rare complication during pregnancy. In most cases the thrombogenic factor was ovarian hyperstimulation syndrome occurred during the process of assisted reproductive technology or inherited or acquired thrombophilia. Authors report a case of jugular vein thrombosis occurred after in vitro fertilization. On the basis of the literature thromboprophylaxis should be indicated for patients who develop ovarian hyperstimulation syndrome, and also be considered for women with inherited or acquired thrombophilia, while undergoing assisted reproductive techniques.

Recommendations for the prevention of pregnancy-associated venous thromboembolism

Pregnancy is a risk factor for venous thromboembolism (VTE), an important cause of maternal morbidity and mortality. Although there is a 4-5-fold increased risk compared to that of nonpregnant women of the same age, the absolute risk is low at no more than two episodes of VTE per 1000 pregnancies. There is uncertainty about which women require thromboprophylaxis during pregnancy or postpartum because of a lack of data from appropriate clinical trials. For this reason, recommendations for prophylaxis should be made only after explaining the available evidence to the patient and taking into account her perception of the balance of risk and benefit in thromboprophylaxis. The aim of these recommendations is to provide clinicians with practical advice to assist in decisions regarding thromboprophylaxis in women considered to be at risk of VTE during pregnancy and the postpartum. The authors are clinicians from across New Zealand and Australia representing the fields of haematology, obstetric medicine, anaesthesiology, maternal-fetal medicine and obstetrics. Authors were invited to review the relevant literature and then worked collaboratively to devise recommendations and resolve areas of controversy. The recommendations contained herein were reached by consensus and represent the opinion of the panel. The absence of randomised clinical trials in this area limits the strength of evidence that can be used, and it is acknowledged that they represent level C evidence. The panel advocates for appropriate clinical studies to be carried out in this patient population to address the inadequacy of present evidence.

Update on management of ovarian hyperstimulation syndrome

Ovarian hyperstimulation syndrome (OHSS) is a relatively common complication of ovarian stimulation and can be life threatening. The pathophysiology of OHSS is characterized by increased capillary permeability, leading to leakage of fluid from the vascular compartment, with third-space fluid accumulation and intravascular dehydration. The increased intra-abdominal pressure indicated that OHSS may be considered a compartment syndrome. Vascular endothelial growth factor, also known as vascular permeability factor, has emerged as one of the mediators intrinsic to the development of OHSS. Conventional management is focused on supportive care until the spontaneous resolution of the condition. The standard of care for treatment-monitoring of appropriate clinical parameters, fluid balance management, thrombosis prophylaxis, and ascites treatment-should prevent severe morbidity in most cases. This review will cover inpatient and outpatient management. The potential therapeutic approach targeting the vascular endothelial growth factor system will be discussed.

[Thrombosis and assisted reproductive techniques (ART)]

Assisted reproductive techniques (ART) concern procedures designed to increase fertility of couples: artificial insemination, in vitro fertilization (IVF), either classical or after intracytoplasmic sperm injection (ICSI), transfer of frozen embryos, or gamete intrafallopian transfer. Their use has greatly increased these last years. They may be associated with severe ovarian hyperstimulation syndrome and one possible major complication is venous or arterial thrombosis. Thromboses are rare but potentially serious with important sequellae. They are mostly observed in unusual sites such as head and neck vessels and the mechanism is still unknown although hypotheses have been proposed. This review is an update of our knowledge and an attempt to consider guidelines for the prevention and treatment of ART-associated thromboses, which frequently occur when the woman is pregnant. Prevention of severe ovarian hyperstimulation by appropriate stimulation procedures, detection of women at risk of hyperstimulation and of women at high risk of thrombosis should allow reduction of the risk of thrombosis, possibly by administration of a thromboprophylaxis at a timing and dose which can be only determined by extrapolation.