The lining of the uterus, called the endometrium, thickens and becomes more vascular during the ovulatory cycle because it is stimulated by progesterone and estrogen. This is necessary for the implantation and nourishment of an embryo.
Once the eggs are ovulated from the follicle, the remaining follicular structure on the ovary is known as the corpus luteum. The corpus luteum produces progesterone to stimulate endometrial development during the luteal phase of the cycle. Inadequate progesterone production can lead to poor endometrial development and a condition termed a luteal phase defect.
An endometrial biopsy involves removing a small amount of endometrial tissue, approximately 12 days after ovulation, and examining it under a microscope. The stage of endometrial cell development is matched up with the cycle day in order to learn if a luteal phase defect is present. An out-of-phase biopsy will not demonstrate typical endometrial cell development. This test is conducted in our Dallas clinic.