New ovarian cyst despite CHC use by patient with PCOs?

Question: I am curious. My understanding is that combined oral contraceptives (COCs) should provide ovarian cyst suppression and/or slow their progression in the setting of presumed polycystic ovary syndrome (PCOS). I had a patient on a COC for almost a year, when she developed a 25 cm mucinous cyst along with other cysts during that time.

Dr. Anita Nelson responds: Thanks for asking. Oral contraceptives do not treat existing functional cysts, but they do suppress the formation of future physiologic cysts. However, you asked specifically about “cysts” in a patient with PCOS. 

Women with PCOS do not have ovarian cysts. By definition, an ovarian cyst must be at least 3 cm in diameter. The ovaries of women with PCOS contain numerous preantral follicles that measure 2-9 mm in size. They are fluid-filled, so it is not wrong to refer to the follicles as being “cystic.” This terminology confuses everyone and is the source of great concern for patients who imagine their ovaries having cysts that need surgery!

Combined hormonal contraceptives provide negative feedback, which women with PCOS lack, so they suppress the maturation of ovarian functional cysts. Women on oral contraceptives often have ultrasound images that look like polycystic ovaries—multiple small cystic structures that will not mature to form a dominant follicle to ovulate. Contraceptive hormones do not dramatically reduce the formation of other non-functional benign cysts like mucinous cystadenomas.

They do, however, dramatically reduce the risk of ovarian cancer, probably by suppression of an oocyte extrusion through the ovarian cortex. The repair of the ovarian cortex after such an extrusion can go awry.

Read more about PCOs in Dr. Nelson’s chapter on Menstrual Disorders in the latest edition of Contraceptive Technology, 22nd edition. ORDER HERE