Which of the following are signs of ovulation? Select all that apply.

Menstruation is the cyclical shedding of the uterine endometrium, resulting in vaginal bleeding. It is the final phase of the menstrual cycle when pregnancy does not occur. The bleeding, which consists of blood, tissue, and mucus, typically lasts for 2 to 7 days. The average volume of blood lost is a crucial parameter for evaluating a woman's reproductive health. Menstrual blood loss is defined as heavy, or menorrhagia, if the volume exceeds 80 mL per cycle, which can lead to iron deficiency anemia.

Rationale for correct answers

B. The typical volume of blood lost during a menstrual period is between 30 and 80 mL. A volume of 30-80 mL is considered the normal range and is a key parameter for defining what is considered a healthy menstrual cycle. Values below this range are considered light and may indicate an issue, while values above 80 mL are considered heavy, or menorrhagia.

Rationale for incorrect answers

A. A blood loss volume of 10–20 mL is considered a very light period, also known as hypomenorrhea. While some women may naturally have lighter periods, a consistently low volume can be a sign of underlying hormonal imbalances, a very thin endometrial lining, or other medical conditions. It does not represent the average or typical blood loss for most menstruating individuals.

C. A blood loss volume of 80–120 mL falls into the range of heavy menstrual bleeding or menorrhagia. Menorrhagia is defined as menstrual blood loss exceeding 80 mL per cycle. This can be caused by various factors, including uterine fibroids, hormonal imbalances, and bleeding disorders. It is not considered a typical or normal volume and can lead to symptoms of anemia, such as fatigue.

D. A blood loss volume of 120–150 mL is significantly higher than the normal range and is a clear indicator of menorrhagia. This level of blood loss can be clinically significant, potentially causing iron deficiency anemia and interfering with a woman's daily life. It requires medical evaluation to identify and treat the underlying cause.

Take home points

• The normal range for menstrual blood loss is 30–80 mL per cycle.
• Menorrhagia is defined as blood loss greater than 80 mL per cycle.
• Heavy bleeding can lead to iron deficiency anemia.
• Abnormal bleeding can be caused by hormonal imbalances or structural issues like uterine fibroids.

Ovulation is the release of a mature ovum from a Graafian follicle due to a luteinizing hormone (LH) surge around day 14 of a typical 28-day menstrual cycle. LH rises from baseline to peak levels of 20–100 mIU/mL just before ovulation. Cervical mucus changes to an estrogen-dominant, clear, stretchy consistency. Basal body temperature rises post-ovulation due to progesterone, increasing by 0.4–1.0°F from a normal pre-ovulatory 97.0–98.0°F. Mittelschmerz, a one-sided pelvic pain, may occur during follicular rupture. There is no endometrial shedding at ovulation; that occurs during menstruation.

Rationale for correct answers

A. Mittelschmerz is the mid-cycle pelvic pain occurring during ovulation as the follicle ruptures and releases the oocyte. It typically localizes to one side and is brief, supporting its association with ovulation.

B. Basal body temperature increases post-ovulation due to the thermogenic effect of progesterone. The rise is measurable the day after ovulation and signals corpus luteum activity.

D. Clear, stretchy cervical mucus (spinnbarkeit) occurs under estrogen influence, which peaks before ovulation. This mucus promotes sperm motility and indicates fertility.

Rationale for incorrect answers

C. Thick cervical mucus is a progesterone-dominant change seen post-ovulation. It acts as a barrier to sperm and is not a sign of impending ovulation but rather luteal phase.

E. Endometrial shedding is menstruation, which occurs if fertilization does not happen. It marks the end of the luteal phase, not ovulation.

Take home points

• Clear, stretchy mucus signals estrogen peak and ovulation.
• Basal body temperature rise occurs after ovulation due to progesterone.
• Mittelschmerz is a physical symptom of follicle rupture.
• Endometrial shedding marks menstruation, not ovulation.