A 28-Year-Old Nulliparous Woman Comes to the Physician Because She

A 28-year-old nulliparous woman comes to the physician because she has been unable to conceive for 3 years. Analysis of her husband's semen has shown normal sperm counts during this time. The patient also reports episodic pelvic and back pain accompanied by painful diarrhea for 5 years. She has about one such episode on average per month that lasts 4-6 days. She has taken ibuprofen for the pain, which has provided some relief. Menses have occurred at regular 29-day intervals since menarche at the age of 14 years and last for 7 days. She is sexually active with her husband and does not use contraception. Vital signs are within normal limits. Pelvic and bimanual examinations are normal; The posterior vaginal fornix is tender to palpation. A hysterosalpingogram 6 months prior showed normal results. This patient's condition most likely involves which of the following?

A) Ectopic endometrial tissue
B) Glycogen-deficient vaginal epithelium
C) Increased endometrial gland/stroma ratio
D) Multiple ovarian cysts with cortical fibrosis
E) Proliferation of endometrial glands within the myometrium