Taking Prometrium

I am 46 years old, no period for over 3 months.  My doctor measured my uterine lining at 19 mm, so he put me on 100 mg Prometrium once a day for 7 days.  At day 3 I started bleeding very heavily (2 pads plus 2 tampons per hour).  I am on day 6 now.  I was told that I would not bleed for about a week after taking Prometrium.  My doctor did not do a biopsy, but told me I could have cancer.  Is bleeding right away on Prometrium normal?  My FSH level 10 months ago was 52.

[Machelle Seibel, MD]

Your lining might have been building up and about to shed even if you did not get the Prometrium. However, the Prometrium might help the lining to eventually stop bleeding. Without progesterone, the lining won't shed evenly and only some of the lining will bleed and some will stay. That causes bleeding to continue off and on. The Prometrium helps to make the entire lining shed. Your experience is not abnormal but  hopefully the bleeding will stop within the next week. If not, talk with your doctor again.

It is generally a good idea to check the lining with an endometrial biopsy to be sure if there are any abnormal cells. Some changes called hyperplasia can occur before cancer changes, which usually take about 10 years to occur. If the bleeding continues for another week or happens again, discuss having an endometrial biopsy with your doctor. It is usually an office procedure that causes only mild cramping. The information is usually very helpful in both diagnosis and treatment.
Machelle M. Seibel, MD