Abnormal Uterine Bleeding and Menstruation

Physiology and Definitions of Normal Menstruation

Normal Menstruation

Definition : Normal menstruation is defined by regular, cyclic shedding of the endometrium secondary to successful ovulation.

  • Cycle Length : Normal ranges from 21 to 35 days.

  • Duration of Menses : Normal duration of menstrual bleeding ranges from 2 to 7 days.

Key Players in a Menstrual Cycle

  • Hypothalamus → Releases Gonadotropin-Releasing Hormone (GnRH)

    • Typical Disruptors : Stress, significant weight loss, tumors, central nervous system medications, puberty, perimenopause.

  • Posterior Pituitary → Releases Follicle-Stimulating Hormone (FSH) and Luteinizing Hormone (LH)

    • Typical Disruptors : Elevated prolactin levels, pituitary tumors, thyroid dysfunction.

  • Ovaries → Produce Estrogen and Progesterone

    • Typical Disruptors : Ovarian failure, hyperandrogenism, ovarian masses.

  • Endometrium → Dynamics of the endometrium can be affected by anatomical anomalies or pelvic outlet obstructions.

  • Outcome : Any disruption in hormone levels can lead to menstrual cycle irregularities.

Ovarian Cycle Phases and Hormonal Levels:

  • Days 1-7 - Follicular Phase

  • Day 14 - Ovulation

  • Days 15-28 - Luteal Phase

  • Hormone Levels

    • FSH : Rises during the follicular phase, peaks mid-cycle.

    • LH : Rises significantly to trigger ovulation.
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