Wednesday, July 25, 2007

Surgery and Birth Control Pills

So you are having surgery and don't want to get pregnant in the postoperative period. What are the issues surrounding surgery that could interfere with your birth control pills (BCPs)? Photo credit

Antibiotics
You most likely will have at least one IV (intravenous) dose of an antibiotic and may be sent home on an antibiotic. Most references (PDR, pharmacy) that I have easy access to continue to say "yes, antibiotics may interfere with the efficacy of your BCP's". This is based on early data (20 yrs ago) which seemed to indicate that when antibiotics were taken along with BCP, more women got pregnant than you would normally expect. Drugs like ampicillin and tetracycline were suspected to interfere with BCPs. However, all the recent studies that have looked at this, have shown that antibiotics do not increase the pregnancy rate at all. These studies point out that the old data was not reliable enough to draw conclusions about pregnancy rates on any of the antibiotics. some antibiotic have been studied and shown not to affect the metabolism of BCPs. Ciporfloxcin is one that does not seem to alter metabolism. Fluconazole (used to treat vaginal yeast infections) does not decrease estrogen levels in pill users, and may actually raise estrogen levels. The safe thing to do is follow the "old rule" and use alternative methods (abstinence, condoms, spermicides) while taking the antibiotics and for an additional 2 weeks.

Postop Nausea and Vomiting
You may end up with postop nausea and vomiting and can't take (or simple forget to take) your birth control pills. If we compare this to when you have the flu, gastritis or a diarrhea condition, the issue becomes whether you are able to absorb the pill. There is little data to address this issue. Fortunately most of these illness (including postop nausea and vomiting) do not last long. It is known that missing up to 10 pills in a row (7 placebo pills and the 1st 3 pills of a pill pack) does not result in ovulation. So it may be unlikely that this would decrease the efficacy of your BCPs. Once again, the safe thing to do is use alternative methods (when feeling up to it)--abstinence, condoms, spermicides for an additional 2 weeks.

Drugs Affecting Birth Control Pills (web article) by Frederick R. Jelovsek MD
Antibiotics and Pregnancy--University of Dubuque Student Health
Check out A Well Timed Period for more information on birth control pills.
5 Reasons for Contraceptive Failure (web article)--About.com, Women's Health

2 comments:

Anonymous said...

Aren't birth control pills contraindicated following many surgeries rbecause of their pro-coagulative effects?

rlbates said...

That has to be balanced with the risk of the patient getting pregnant. If the risk of DVT's (type of surgery, pt age, smoker, use of BCP's, etc) is high enough, then the patient should be placed on something like Lovenox to prevent the blood clots.