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Functional and
Dysfunctional Uterine
Bleeding
Chapter 24
Kristin Van Heertum, MD
❍ Define the normal menstrual cycle.
The normal menstrual cycle is 28 days with a flow lasting 2 to 7 days. The variation in cycle length is set at 24 to
35 days.
❍ In a normal menstrual cycle, when does ovulation typically occur?
Ovulation in a 28-day cycle occurs on day 14. The luteal (secretory) phase of the cycle is constant at 14 days. The
estrogenic (follicular/proliferative) phase of the cycle can be variable.
❍ A woman normally has 32-day cycles. In this woman, when does ovulation occur?
In this clinical situation, ovulation should occur on day 18. The luteal phase of the cycle should remain constant at
14 days.
❍ Name the hormones, and their source, that are involved in maintaining a normal menstrual cycle.
From the ovary: Estrogen, progesterone, and inhibin A.
From the pituitary: Follicle-stimulating hormone (FSH) and luteinizing hormone (LH). Prolactin and
thyroid-stimulating hormone (TSH) are also vital in maintaining a normal menstrual cycle.
From the hypothalamus: Gonadotropin-releasing hormone (GnRH).
❍ What are the three layers of the endometrium?
(1) The pars basalis, (2) the zona spongiosa, and (3) the superficial zona compacta. The zona spongiosa and zona
compacta make up the stratum functionalis, which is shed during menses.
❍ What vascular event triggers shedding of the endometrium?
Spasm of the spiral arteries resulting in ischemia of the tissue and sloughing.
❍ Describe the effect of estrogen on the endometrium.
Estrogen causes proliferation of the endometrium. The endometrial glands lengthen and the glandular epithelium
becomes pseudostratified. Mitotic activity is present in both the glands and the stroma.