 The Menstrual Cycle NURS 541 – Women’s Healthcare: Diagnosis and Management

Start with the basics….  Menstrual cycle  Normal, physiologic process  Typical menstrual cycle is 28 days long  Unique to each woman  Range days considered normal  Regular cycles = predictably occurs at same time interval  Irregular cycles = different cycle lengths, unpredictable  Typical length of menses  4-6 days (2-8 days considered normal)  Amount of menstrual flow  Average 50ml (20-80ml considered normal)

Start with the basics…  Menarche  Age at first menses – between age  Age of menarche influenced by:  Pubertal changes, genetics, lean body mass %  Menopause  Age at which menses cease – average age  Menstrual cycles will occur in normally cycling individuals from menarche to menopause

Multiple cycles at play…  Hormonal cycles  Ovarian cycles  Endometrial cycles

Hormonal cycles  Stems from the hypothalamus/pituitary/ovarian axis (HPOA)  Hypothalamus  GnRH  Anterior pituitary  GH, TSH, ACTH, MSH, PRL, FSH, LH  FSH and LH primarily responsible for menstrual cycle  Ovaries  Estrogen, progesterone

Normal Menstrual Cycle

Hormonal cycles  Positive and negative feedback loops  High GnRH stimulates production of FSH and LH (gonadotropins)  Follicle-stimulating hormone (FSH)  Targets ovary  FSH  growth of follicles  production of estrogen/progesterone  NEGATIVE feedback loop: high estrogen or progesterone = low FSH  Luteinizing hormone (LH)  Targets dominant follicle and corpus luteum  Estrogen triggers POSITIVE feedback loop with LH (and FSH) mid- cycle, creating LH surge and ovulation  Progesterone from the corpus luteum  decreases GnRH

Ovarian cycle  Ovarian cycle  Follicular phase  Development of follicles day 1 through day 14  Day 5-7 one dominant follicle develops  Ovulatory phase  Release of the dominant follicle around day 14  Triggered by LH surge, occurs hrs after surge  Estrogen also peaks around that time  Luteal phase  Dominant follicle becomes corpus luteum  Secreting estrogen and progesterone for up to 8 days post ovulation  Once estrogen/progesterone decreases, FSH/LH increase and menstrual cycle begins again

Ovarian Cycle

Endometrial cycle  Endometrial cycle  Proliferative phase  From day 4-5 to day 14, stops with ovulation  Growth of endometrium in preparation for ovum, influenced by estrogen  Secretory phase  Starts following ovulation  Thickening of endometrium with increased secretions, like a thick “cushion” for the fertilized ovum  Endometrium becomes unstable near of end of secretory phase, due to low estrogen/progesterone levels  Menstrual phase  Prostaglandins trigger contractions, sloughing off degraded endometrium  Lasts 4-6 days

Menstrual History  Age of menarche  Menstrual cycle length  Duration of menses  Menstrual cycle flow  Associated symptoms

Common scenario  Mischa tells you that she is having regular periods, “once a month”. The last one ended on the 22 nd of the month and was 24 days long. It is very heavy on the 2 nd day but otherwise “okay”.  Last menstrual period (LMP)  First day of last menses  Length of menstrual cycle  Days from first day of one cycle to first day of next cycle  Make sure you clarify information put on the intake forms!!

Gathering menstrual history  How long is your menstrual cycle?  How many days do you bleed?  How many pads/tampons do you use in an hour on your heavy days?  Are your cycles regular? Irregular?  Heavy? Light?  Long? Short?

What is “Abnormal”?  Abnormal duration of cycle  Frequent – polymenorrhea - <24 day cycles  Normal – day cycles  Infrequent – oligomenorrhea - >38 day cycles  Abnormal regularity of cycle  Absent menses – amenorrhea – no cycles  Normal - +/ day variation between cycles  Irregular – metrorrhagia - variation > 20 days

What is “Abnormal”?  Abnormal duration of flow  Prolonged – hypermenorrhea - > 8 days  Normal – days  Shortened – hypomenorrhea - < 4.5 days  Abnormal amount of blood loss (flow)  Heavy – menorrhagia - > 80 mL  Normal – 5-80 mL  Light – hypomenorrhea - < 5 mL

Estimating blood flow Wyatt KM, Dimmock PW, Walker TJ, et al. Determination of total menstrual blood loss. Fertil Steril. 2001;76(1):125–131 (27)

Exercise  Break off into 5 groups  Group 1  Hormones – LH, FSH, estrogen, progesterone  Group 2  Endometrium – proliferative phase, secretory phase, menstrual phase  Group 3  Ovaries – follicular phase, ovarian phase, luteal phase  Group 4  Menstrual history  Group 5  Describing abnormal menses  10 minutes to plan  3 minutes to present a quick and dirty way to remember (to share with your colleagues)