Understanding the Menstrual Cycle and Common Disorders

• Follicular Phase: Driven by FSH, this phase involves the maturation of an ovarian follicle.
• Ovulation: Typically occurring around day 14 of a 28-day cycle, ovulation is the moment a mature egg (ovum) is released from the ovary.

Clinical Note: Signs of Ovulation Students should recognize that ovulation can be identified by specific physiological changes, including:

• Changes in cervical mucus consistency.
• A shift in basal body temperature.
• Mittelschmerz, which is localized pelvic pain felt during ovulation.

3. The Endometrial Cycle

While the ovaries are preparing an egg, the uterus is preparing a home for a potential embryo. This is known as the endometrial cycle, which is heavily influenced by ovarian hormones like estrogen and progesterone.

• Proliferative Phase: Under the influence of estrogen, the endometrial lining thickens.
• Secretory Phase: Following ovulation, progesterone levels rise, preparing the lining for implantation.
• Ischemic Phase: If fertilization does not occur, the blood supply to the endometrium is constricted.
• Menstruation: The functional layer of the endometrium sheds, while the basal layer remains to regenerate the lining for the next cycle.

Menstrual Disorders and Dysfunctions

When the hormonal or physiological balance of these cycles is disrupted, various menstrual disorders can arise.

Amenorrhea

Amenorrhea refers to the absence of menstruation.

• Primary Amenorrhea: The absence of menarche by age 15.
• Secondary Amenorrhea: The absence of a menstrual cycle for 6 months after menstruation has previously occurred.
• Causes: Hypogonadotropic amenorrhea (hypothalamus dysfunction) can be caused by malnutrition, excessive exercise (common in runners), or thyroid issues (hyper/hypothyroidism).

Dysmenorrhea

Dysmenorrhea is defined as painful or difficult menstruation.

• Primary Dysmenorrhea: Pain not associated with a specific disease, often caused by the action of prostaglandins on the uterus. Symptoms include severe intermittent cramping that may radiate to the lower back and thighs, as well as nausea and fatigue.
• Secondary Dysmenorrhea: Pain caused by an underlying pelvic condition, such as uterine fibroids or endometriosis.

Endometriosis

Endometriosis occurs when endometrial tissue grows outside of the uterus. This can lead to significant pelvic pain, pain during intercourse (dyspareunia), and gastrointestinal symptoms like diarrhea or pain during defecation.

Premenstrual Syndromes

• PMS (Premenstrual Syndrome): A complex condition of the luteal phase involving fluid retention (bloating), emotional changes, breast tenderness, and fatigue.
• PMDD (Premenstrual Dysphoric Disorder): A more severe form of PMS characterized by marked irritability, anxiety, and a sense of being overwhelmed.

Menopause

The final stage of the reproductive years is menopause, defined as the point in time when a person has gone one full year without a menstrual cycle. This marks the end of reproductive ability and is often accompanied by vasomotor symptoms (like hot flashes), tissue atrophy, and genitourinary changes.

Vocabulary Quick-Reference

• Oligo-: Few (e.g., Oligomenorrhea)
• -rragia: Excess or abnormal flow (e.g., Menorrhagia)
• Dys-: Pain or difficult (e.g., Dysmenorrhea)
• A-: Without or lack of (e.g., Amenorrhea)