"Ask Dr. Cook" is a series of questions and answers regarding endometriosis. The current subject and answer can be found on Current Ask Dr. Cook web page. The questions may represent a summary of questions I have been asked by several different patients. I hope you find this information helpful. If you have a question you would like answered, please Submit A Question.

Does Endometriosis Increase the Risk of Miscarriage?

Question:
Is there a higher miscarriage rate in women with endometriosis who conceive? At what stage of your pregnancy can you regard yourself as safe from miscarriage. Are there any tests that can or should be performed during the high risk phase?

Answer:
We do not have a definite answer to the question "does endometriosis cause an increase in the miscarriage rate". Some physicians in the infertility field do feel there is an increase in the risk of miscarriage with endometriosis. Some feel there is no increase in the miscarriage rate. The reason we do not have a definite answer to this question, is that there are problems with the studies examining this issue. The most recent edition of the widely read textbook Clinical Gynecologic Endocrinology and Infertility states "In appropriately controlled studies the [miscarriage] rate was in the normal range in women with endometriosis who were not treated, and it is likely that previous studies were flawed by their choice of control [miscarriage] rates". In English what this means is that many of the earlier studies used historical controls. That is, the study looked at the miscarriage rates in patients prior to treatment of endometriosis compared to the miscarriage rates in the same patients after treatment of endometriosis. In these studies patients had lower miscarriage rates after treatment. One of the best studies was published back in 1986. In this study, half of the patients with endometriosis were treated surgically and the other half was not treated (either surgically or medically). Both the treated and untreated groups showed a significant decrease in the miscarriage rate. The miscarriage rate in the treated group was also significantly lower than the untreated group. Unfortunately, no study has been published which prospectively looks at two identical groups of women, with the exception of endo verses no endo, and followed their miscarriage rate.

The vast majority of miscarriages occur within the first three months of pregnancy. It is rare to have problems later than 10-12 weeks, but it possible. You are not entirely safe from "miscarriage" until the baby is in your hands after delivery.

I use the following approach with my patients during the first trimester, which can be considered the high risk phase. After a positive pregnancy test, I usually obtain what is called a quantitative beta hCG. This is a blood test that tells you the exact level of pregnancy hormone present. If the pregnancy is developing normally, the level should nearly double every other day. I usually perform a transvaginal sonogram (ultrasound) once the level beta hCG gets up in the range of about 3,000 . At this point a gestational sac should be visible inside the uterus in a normal pregnancy (some older sonogram machines may require a level of 6,000 to see a gestational sac). Two weeks later, usually about eight weeks from the last period, a repeat sonogram should demonstrate a fetus and heartbeat in a normal pregnancy. If everything looks OK at this point your chances are very good that that your pregnancy will continue and its time to pop open your non-alcoholic champagne. At a later time your OB will perform the routine tests for neural tube defects, diabetes, etc.

If the beta hCG level is not rising appropriately or if no gestational sac is seen as described above, then an ectopic (tubal) pregnancy must be considered and managed appropriately.

Updatede October 29, 2005