Combined oral contraception and the risk of venous thromboembolism

Disorders of Menstruation in Adolescent Girls

Abnormal menstruation in adolescent girls can cause psychological and physical strain from excess, unpredictable, painful, or even absent bleeding. Care providers who understand what is normal and what is concerning can educate and often reassure the young woman and her family. When there is an abnormal or concerning scenario, they can initiate investigations and/or treatment in an expedient fashion to limit psychosocial and/or physical morbidity. This article provides pediatricians, family doctors, nurse practitioners, and adult gynecologists with the knowledge and understanding of the common complaints, differential diagnoses, and treatment strategies.

SOGC clinical practice guideline. No. 252, December 2010. Oral contraceptives and the risk of venous thromboembolism: an update

OBJECTIVE

To provide current and emerging evidence on oral contraceptives and the risk of venous thromboembolism.

EVIDENCE

Articles published in English from 2005 were retrieved through searches of PubMed and Medline, using the following terms: venous thromboembolism, VTE, contraception, oral contraceptives, hormonal contraception. Results were restricted to systematic reviews, randomized control trials/controlled clinical trials, and observational studies. Searches were updated on a regular basis and incorporated in the guideline to May 2010. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology assessment-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies.

VALUES

The quality of evidence was rated using the criteria described by the Canadian Task Force on Preventive Health Care (Table). SUMMARY STATEMENTS: 1. Modern oral contraceptives offer highly effective contraception and a range of non-contraceptive benefits. (I) 2. Venous thromboembolism, although rare, remains one of the serious adverse consequences of hormonal contraception. Best evidence indicates that venous thromboembolism rates in non-users of reproductive age approximate 4-5/10 000 women per year; rates in oral contraceptive users are in the range of 9-10/10 000 women per year. For comparison, venous thromboembolism rates in pregnancy approach 29/10 000 overall and may reach 300-400/10 000 in the immediate postpartum period. (II-1) 3. Research demonstrates that oral contraceptives with ≤ 35 µg of ethinyl estradiol carry a lower risk of venous thromboembolism than oral contraceptives with 50 µg. (II-2) Although preliminary data suggest a possible further reduction in venous thromboembolism with oral contraceptives with < 35 µg ethinyl estradiol, robust data to support this conclusion are presently lacking. 4. Recent contradictory evidence and the ensuing media coverage of the venous thromboembolism risk attributed to the progestin component of certain newer oral contraceptive products have led to fear and confusion about the safety of oral contraceptives in general and drospirenone-containing oral contraceptives in particular. "Pill scares" of this nature have occurred in the past, with panic stopping of the pill, increased rates of unplanned pregnancy, and no subsequent decrease in venous thromboembolism rates. (II-3) 5. Two high quality research studies that addressed the venous thromboembolism risk associated with various oral contraceptives found comparable venous thromboembolism rates with drospirenone-containing oral contraceptives and other approved products. (II-1) 6. Two reports suggesting an increased risk of venous thromboembolism with drospirenone-containing oral contraceptives have significant methodological flaws that render their conclusions suspect. It seems likely that residual confounding could have distorted both the results and the conclusions of these reports. (II-3).

A survey of recommendations by gynecologists in Canada regarding oral contraceptive use in the perioperative period

OBJECTIVE

This survey was conducted to determine the practice patterns of gynecologists in Canada regarding the discontinuation of oral contraceptives before gynecologic surgical procedures.

STUDY DESIGN

In May and June of 1997, surveys were sent to all obstetricians and gynecologists on the mailing list of the Society of Obstetricians and Gynaecologists of Canada.

RESULTS

Of the 1472 surveys that were sent, 702 of the surveys were completed and returned, for a response rate of 48%. More than 90% of the gynecologists who were surveyed would advise their patients to continue using oral contraceptives before relatively minor surgical procedures and <1% of them would use low-dose heparin before these procedures. Rates of oral contraceptive discontinuation increased as the extent of the surgical intervention increased: Prolonged laparoscopy (39.8%), vaginal repairs and hysterectomy (54.7%), and abdominal hysterectomy or adnexectomy (56.1%). Just over one half of the gynecologists (56.1%) indicated that they would advise discontinuation > or =4 weeks before the surgical procedure, which is the minimum time required for the prothrombotic changes that are associated with oral contraceptive use to return to baseline. Less than 10% of the surgeons indicated that they would use low-dose heparin even when the patient was advised to continue taking oral contraceptives before major surgical procedures.

CONCLUSION

The controversy over whether young healthy women should discontinue oral contraceptive use before major surgical procedures that are associated with immobility is reflected by a lack of consensus among gynecologists in Canada.