Oral contraceptives and surgery: reduced antithrombin and antifactor Xa levels without postoperative venous thrombosis in low-risk patients

Association of Surgical Risk With Exogenous Hormone Use in Transgender Patients: A Systematic Review

Importance

A growing number of transgender patients are receiving gender-affirming hormone treatments. It is unclear whether the evidence supports the current practice of routinely discontinuing these hormones prior to surgery.

Objective

To determine how medications used in cross-sex hormone treatment (CSHT) affect perioperative risk.

Evidence Review

A series of searches were carried out in PubMed and Excerpta Medica Database to identify articles using each of the terms testosterone, estrogen, estradiol, oral contraceptive, spironolactone, cyproterone acetate, finasteride, dutasteride, leuprolide, goserelin, and histrelin, in combination with the terms surgery, perioperative, thrombosis, thromboembolism, and operative. The search was not restricted to perioperative outcomes in transgender populations because many surgeons routinely discontinue hormone use prior to surgery in this population, which makes it impossible to study how hormones affect outcomes. Additional sources were also identified from the texts of reviewed articles. Articles were excluded if they were animal studies or case reports, did not explicitly discuss surgical outcomes, or were restricted to removal of hormonally sensitive tissues.

Findings

Eighteen articles addressing perioperative outcomes were identified by this systematic review, including 1 on CSHT, 12 on estrogens and progesterones, 1 on testosterone, and 4 on spironolactone and antiandrogens. Data were limited, but use of exogenous testosterone was not found to be associated with an increased risk of venous thromboembolism or other complications during surgery. Moderate evidence suggests that spironolactone is not associated with negative surgical outcomes. The data linking estrogen use and thrombosis is inconsistent in the perioperative period and does not address the types of estrogens most often used for CSHT.

Conclusions and Relevance

Current evidence does not support routine discontinuation of all CSHT prior to surgery, particularly given the lack of information on risks associated with resuming these medications after they have been stopped. Evidence suggests there is no need to discontinue either testosterone or spironolactone, although their association with perioperative outcome quality has not been studied in depth. Most of the evidence that supports discontinuation of estrogen prior to surgery is based on oral estrogen regimens that are not typically used in transgender patients, and even with those formulations, there are conflicting reports on perioperative risk. Further research is needed to determine the safety of continuing hormone treatment and elucidate risks of short-term discontinuation.

Deep-vein thrombosis prophylaxis in foot and ankle surgery: what is the current state of practice?

BACKGROUND

When contemplating thromboprophylaxis for patients undergoing elective foot and ankle surgery the potential for complications secondary to venous thromboembolism (VTE) must be balanced against the cost, risk, and effectiveness of prophylactic treatment. The incidence of pulmonary embolism (PE) following foot and ankle surgery is considerably lower than after hip or knee surgery. The purpose of this study was to assess current trends in practice regarding VTE prophylaxis among expert orthopaedic foot and ankle surgeons.

METHODS

An e-mail-based survey of active AOFAS (American Orthopaedic Foot and Ankle Society) committee members was conducted (n = 100). Surgeons were questioned as to their use, type, and duration of thromboprophylaxis following elective ankle fusion surgery. Scenarios included the following: (1) A 50-year-old woman with no risk factors; (2) a 50-year-old woman with a history of PE; and (3) a 35-year-old woman actively using birth control pills (BCPs).

RESULTS

The response rate for the survey was 80% (80/100). Replies regarding the use of thromboprophylaxis were as follows: (1) in the absence of risk factors, 57% of respondents (45/80) answered, "No prophylaxis required"; (2) for the scenario in which the patient had experienced a previous PE, 97.5% of respondents (78/80) answered, "Yes" to prophylaxis use; (3) for the scenario in which the patient was on BCP, 61.3% of respondents (49/80) stated that they would give some type of thromboprophylaxis. The most commonly recommended methods of prophylaxis were aspirin, 49% (24/49), and low-molecular-weight heparin, 47% (23/49). The recommended length of time for thromboprophylaxis varied widely, from 1 day to more than 6 weeks.

CONCLUSION

. There remains wide variation in the practice of deep-vein thrombosis thromboprophylaxis within the foot and ankle community. Because risks for foot and ankle patients differ from those in the well-studied areas of hip and knee, specific guidelines are needed for foot and ankle surgery.

LEVELS OF EVIDENCE

Level V: Expert Opinion.

Evidence-based risk factors for postoperative deep vein thrombosis

BACKGROUND

Deep vein thrombosis (DVT) is a common postoperative complication that is associated with significant morbidity and mortality. Thromboprophylaxis has been shown to be underused. In the absence of prophylaxis, rates as high as 50% have been reported following orthopaedic surgery, and 25% following general surgery. Many risk factors have been suggested but there is often little evidence to support these claims.

METHODS

A systematic review was performed to determine the evidence base behind each suggested risk factor, and, where sufficient data were available, a random-effects meta-analysis was performed.

RESULTS

There is evidence to support a significant association between increased age, obesity, a past history of thromboembolism, varicose veins, the oral contraceptive pill, malignancy, Factor V Leiden gene mutation, general anaesthesia and orthopaedic surgery, with higher rates of postoperative DVT, although there remain some variables within the study designs that may lead to overestimation of effect. There is no evidence to support the suggested risk factors of hormone replacement therapy, gender, ethnicity or race, chemotherapy, other thrombophilias, cardiovascular factors, smoking and blood type.

CONCLUSIONS

An accurate knowledge of evidence-based risk factors is important in predicting and preventing postoperative DVT, and can be incorporated into a decision support system for appropriate thromboprophylaxis use.

Epidemiology, risk factors and prophylaxis of venous thrombo-embolism in obstetrics and gynaecology

Venous thrombo-embolism remains a major cause of mortality and morbidity following gynaecological surgery and in association with pregnancy and delivery. Specific risk factors can be identified pre-operatively and before or during pregnancy and delivery. Clinicians and units should develop guidelines for risk assessment and the implementation of specific thromboprophylactic measures in patients considered to have significant risk. The main prophylactic techniques are unfractionated and low-molecular-weight heparins and physical methods such as graduated elastic compression stockings. It should be noted that there are particular concerns with regard to the use of pharmacological thromboprophylaxis with both heparin and warfarin in pregnancy. Unfractionated heparin is associated with osteoporotic problems, allergy and heparin-induced thrombocytopenia which can cause significant thrombotic problems. Warfarin is associated with teratogenesis and the risk of bleeding in mother and fetus. Clearly, where antenatal thromboprophylaxis is to be used, the risk of the anticoagulants employed must be weighed against the potential benefits. Such assessment might be best done prior to pregnancy in order that the patient can enter pregnancy with a clear view of the potential hazards and benefits. Low-molecular-weight heparins are being increasingly used in pregnancy but it is unclear to what extent they are safer than unfractionated heparins. However, they do appear to have substantially less risk of heparin-induced thrombocytopenia and possibly less risk of heparin-induced osteoporosis. Increasingly, thrombophilia is recognized as underlying many thrombotic problems, particularly in young women, and when the events occur in association with pregnancy. In view of the complexity in the management of such patients, it is important that they be referred to a unit with specific expertise in the management of thrombophilia.

Oral contraceptive therapy and the surgical management of ENT patients: a review of current clinical practice

The current policy of British Otolaryngologists with regard to the preoperative cessation of the oral contraceptive pill is reported. This is based on a confidential questionnaire sent to all members of the British Association of Otolaryngologists. The overall response rate was 66%, 91% of which were from practising otolaryngologists and forms the basis of this report, the remaining 9% being from respondents not engaged in active surgery. Although there is evidence to show an increased risk of developing thromboembolic complications after major abdominal, gynaecological and hip surgery in those patients taking the oestrogen-containing contraceptive pill, the risk following minor and intermediate surgery (which forms the bulk of the otolaryngologist's workload) is not known. Not surprisingly therefore the results of the survey show a varied policy across the country with 36.5% of respondents choosing to continue the pill and 25% always stopping the pill preoperatively. The remainder elect to stop the pill only in certain circumstances.

Effects of newer oral contraceptives on the inhibition of coagulation and fibrinolysis in relation to dosage and type of steroid

Oral contraceptives influence plasma proteins, causing changes in plasma procoagulants and fibrinolytic effectors. Estrogen is thought to be responsible for these changes, whereas progestogens, in particular those with an androgenic effect, may influence the magnitude of the changes. This concept is consistent with epidemiologic studies, suggesting a correlation between estrogen dose and cardiovascular episodes in oral contraceptive users. A delayed resolution of fibrin might contribute to an increased risk caused by decreased coagulation inhibition or fibrinolytic efficacy. Estrogen (30 micrograms or more) has a dose-dependent effect on clotting factors, including antithrombin III and proteins C and S. The effect of high- and low-dose oral contraceptives containing various progestogens on the fibrinolytic system is less clear. We have found that low-dose oral contraceptives containing levonorgestrel or lynestrenol enhance fibrinolysis, as revealed by an increase in plasminogen (30% to 40%), a decrease in histidine-rich glycoprotein (15% to 26%), an increase in tissue plasminogen activator activity (greater than 150%), and a decrease in tissue plasminogen activator inhibition (30% to 40%), concomitant with a slight decrease in tissue plasminogen activator antigen level (15% to 20%). New oral contraceptives contain less androgenic progestogens. Preliminary results of an ongoing study of women receiving either 20 micrograms of ethinyl estradiol with 150 micrograms of desogestrel or 30 micrograms of ethinyl estradiol plus 75 micrograms of gestodene revealed no change or changes similar to the older low-dose preparations after 6 months of treatment. Of particular importance was the finding that coagulation activation, expressed by the levels of thrombin-antithrombin III-complexes, fibrin formation, and the efficacy of fibrinolysis, expressed by the levels of fibrin degradation products, was identical in the two groups.

Oral contraception and post-operative thromboembolism: an epidemiological review

It has been stated that oestrogen-containing oral contraceptive medication should be discontinued one month prior to surgery, to avoid an increased incidence of post-operative thromboembolism. Others have suggested that the risk of post-operative morbidity is low compared with the risk of pre-operative pregnancy, and that in most cases no such action should be taken. The evidence from clinical investigation is reviewed, with particular reference to study design. It is found that all studies so far conducted are subject to sources of bias or confounding which render their results inconclusive. There is a need for a randomised control trial comparing the effects of discontinuing or continuing oral contraception prior to surgery. Meanwhile, with a post-operative risk inferred but not conclusively demonstrated, if oral contraception is to be withdrawn prior to surgery, great care must be taken to reduce the risk of ensuing pregnancy to as near zero as possible.

The relative contributions of antithrombin III during heparin treatment, and of clinically recognisable risk factors, to early recurrence of venous thromboembolism

The influence of antithrombin III (ATIII) level and ATIII activity, measured during intravenous heparin treatment for venous thromboembolism (VTE), on 'heparin requirement' (the heparin dose required to prolong the activated partial thromboplastin time (APTT) into its designated therapeutic range), and on the likelihood of recurrent VTE during the first month of anticoagulant therapy, were examined in a prospective study of 232 patients with VTE treated according to a standard protocol. 15 patients with recurrent VTE (6.5%) had a lower mean APTT during heparin treatment than patients without recurrence; a finding due partly to their heparin requirement. However, there was no measurable relationship between ATIII level or ATIII activity and either heparin requirement or recurrence of VTE. By contrast, both the presence of disseminated malignancy and the development of heparin induced thrombocytopenia were powerful, clinically recognisable, risk factors for recurrence during or soon after heparin therapy.