If a full menstrual flow occurs while the woman is taking her pills, this usually means she has ovulated despite the BCPs.

This doesn’t mean she will become pregnant, since the BCP has a number of ways of preventing pregnancy in addition to inhibiting ovulation, but it may increase slightly the statistical chance of pregnancy.

If she continues to take the same BCP according to her usual routine, the BCP may, over the next month or two, achieve reasonable control over the menstrual cycle, particularly if she is diligent in taking her pills daily, at the same time each day.

Alternatively, many gynecologists will switch her to a different BCP, one more likely to be successful in suppressing her own ovarian function. (that is, stronger progestin with longer half-life.) The switch can be made at any time.

Pregnancy may also cause bleeding during the pill cycle that resembles a menstrual period. This is unlikely (but not impossible) since the BCPs are highly effective in preventing pregnancy, even if taken imperfectly.

Other causes for episodic abnormal bleeding include uterine fibroid tumors, uterine polyps, trauma and malignancy. A physical exam will reveal some of these but others will require more sophisticated gynecologic evaluation. Remember, uterine malignancy under age 35 is very rare and vaginal malignancy is extraordinarily rare. Cervical malignancy in the presence of a normal Pap smear is also very uncommon.

In a military setting, if abnormal bleeding persists, gynecologic consultation will be necessary, but this can be safely accomplished within weeks to months so long as the:

• patient is not bleeding heavily and continuously
• examination is normal
• Pap smear is within 1 year
• patient is less than 35 years old