Infertility is the inability of a couple to achieve pregnancy after one full year of unprotected sex without any form of birth control. Infertility testing consists of a variety of different tests that help determine why the woman cannot become pregnant. Some tests are as simple as a physical exam or medical history but many tests can be rather invasive. Patients may feel a little discomfort and they may have mild to severe risk of infection. Endometrial biopsy is one of the mild procedures that a physician may suggest for a couple seeking answers to their fertility problems. This test lets the couple know if the woman is ovulating, and if the lining of her uterus is prepared to nourish an egg.
An understanding of progesterone production is required to understand a endometrial biopsy. There are different types of tissue that line the uterus, depending on the day within a woman's 28-day menstrual cycle. Between days 22 and 25, levels of progesterone, a hormone released by the ovaries, are elevated. This increase suggests that ovulation, the release of an egg from the ovary, has occurred. This progesterone-stimulated tissue is necessary to nourish an egg long enough for it to be fertilized by sperm. When this hormone is low, the egg cannot survive due to the low levels of progesterone. Endometrial biopsy tests these progesterone levels and allows a physician to determine if they are too high or too low.
When a physician, usually a gynecologist, suggests an endometrial biopsy, they want to check whether the tissue that lines the uterus has properly responded to the elevated levels of progesterone. A well-nurtured and developed lining that is full of progesterone provides the right environment for a healthy egg to be fertilized by equally healthy sperm. Therefore, care is taken to schedule the patient close to her menstruation, preferably 1-3 days before her period is expected.