Menstrual cycle

Menstrual cycle content exclusively for nursing and medical students

1. MENSTRUAL CYCLE Kshyanaprava Behera Assistant Professor SOA University

2. WHAT IS Menstruation? The process in a woman of discharging blood and other material from the lining of the uterus at intervals of about one lunar month (28 days) from puberty until the menopause, except during pregnancy.

3. Menstrual cycle Menstruation is not the same as the menstrual cycle. The Menstrual cycle describes the cyclic changes in a woman’s body going through menstruation , the follicular phase , ovulation , the luteal phase and back to menstruation again to begin the cycle. Menstruation is therefore one of the 4 phases of the menstrual cycle.

4. Importance Cycle of natural changes that occurs in the uterus and ovary as an essential part of making sexual reproduction possible. Essential for the production of eggs. Preparation of the uterus for pregnancy. Fertile period of a woman’s life between menarche and menopause.

5. Key terminologies Menarche: Age at onset of menstruation , 9 year to 16 year. Primary amenorrhea: Absence of menstruation despite signs of puberty Secondary amenorrhea: Absence of menstruation for 3-6 months in a woman who previously menstruated Dysfunctional uterine bleeding: Irregular bleeding due to anovulation or anovulatory cycle

6. Menorrhagia: Regular menstrual intervals, excessive flow and duration Metrorrhagia : Irregular menstrual intervals, excessive flow and duration Oligomenorrhea : Menstrual interval greater than 35 days Anovulation / anovulatory : Menstrual cycle without ovulation Dysmenorrhea : Menstrual cramping/pain

7. Normal features of menstruation Duration of menstrual flow Quality of the menstruum , Amount of blood loss, The flow pattern and Associated symptoms.

8. Duration Last from 3 to 7 days. The exact duration varies from woman to woman. It however shows little or no variation for the same woman from cycle to cycle. Most women do not experience cycle to cycle changes more than 1 or 2 days. It is unusual for the same woman to have wide swings such as 3 days duration in one cycle and 7 days in another.

9. Menstrual blood is normally bright or light red in color like the bleeding that occurs after a knife cut or similar injury. It could look brown in some few women and still be normal menstruation. It must not have a foul odor . Small clots may be a normal part of menstrual blood.

10. Amount of blood loss The average blood loss during normal menstruation is about 35 ml , with a range of 10 to 80 ml . Usually understood from the number of pads soaked.

11. The flow pattern Normally, as menses begin to flow, the amount of blood loss seems to increase gradually until it attains a maximum and then starts diminishing as the end of the flow draws near. This pattern is described as crescendodecrescendo pattern .

12. Associated symptoms Normal menstruation may be accompanied by other symptoms such as  Breasts fullness,  Mild lower abdominal pain or Irritability.  Fluid retention  Cramping  Mood swings  Weight gain  Breast tenderness  Diarrhea  Constipation

13. Hormone Control of Cycle Hypothalamo -pituitary-ovarian axis • Cycle controlled by hypothalamus, however this can be influenced by higher centres within the brain • i.e. due to stress or anxiety • Hypothalamus releases gonadotrophin releasing hormone in pulsatile manner  anterior pituitary release of LH and FSH

14. Hormone Control Follicular stimulating hormone (FSH) – glycoprotein Stimulates follicular maturation during follicular phase Stimulates steroid hormone secretion – oestrogen (by the granulosa cells of mature ovarian follicle) • Lutenizing Hormone (LH) – glycoprotein • Stimulates steroid hormone secretion – oestrogen • Ovulation – mid-cycle surge of LH • Progesterone production by corpus luteum • Negative feedback mechanism controls cycle

15. Phases of menstrual cycle

16. Ovarian Cycle – Follicular Phase Days 1-8 – FSH and LH relatively high levels o Stimulate development of 10-20 follicles o Results in full maturation of a single dominant follicle – appearing in midfollicular phase o Remainder undergo atresia o High LH and FSH triggered by drop in oestrogen and progesterone levels from last cycle . o Oestrogen levels start to rise as follicular development occurs

17. Ovarian Cycle – Follicular Phase (2) Days 9-14 – o Follicle increases in size o Localized accumulation of fluid among granulosa cells, fluid-filled central cavity called antrum o Transforming primary follicle to Graafian follicle o Oocyte occupies excentric position – surrounded by cumulus oophorus – 2-3 layers of granulosa cells o Rise in oestrogen by granulosa cells, associated with follicular maturation o Inhibin produced by granulosa cells – restricting number of follicles maturing

18. Ovarian Cycle - Ovulation Day 14 – rapid enlargement of follicle and rupture of the follicle with extrusion of the oocyte and adherent cumulus oophorus • Some women get pain before rupture – called Mittelschmerz • Rise in oestrogen , mid-cycle surge of LH and to a lesser extent FSH then ovulation occure • Immediately before ovulation there is a drop in oestrogen and an increase in progesterone . • Ovulation follows within 18 hours of midcycle surge of LH • If not enough of a LH surge – then no ovulation occurs – anovulatory

19. Ovarian Cycle - Luteal Phase Days 15-28 – remainder of the follicle retained in the ovary – penetrated by capillaries and fibroblasts from the theca • Grunlosa cells undergo luteinization called corpus luteum formation – the major source of sex hormones – oestrogen and progesterone secreted during postovulary phase • This leads to marked increase in progesterone and oestrogen

20. Ovarian Cycle If conception and implantation occur: • Corpus luteum doesn’t regress – maintained by gonadotrophins secreted by trophoblasts . If conception doesn’t occur successfull : • Corpus luteum regresses and menstruation occurs • Drops in steroid sex hormones leads to a rise in gonadotrophin levels (FH and LSH) that initiate next cycle

21. Uterine Cycle • Influenced by the cyclical production of steroid hormones • Causes changes to the uterus • Involving the endometrium and cervical mucus

22. Uterine Cycle – Endometrium Overview • Two layered • Superficial layer that sheds during the menstrual cycle • Basal layer that doesn’t take part, but regenerates the superficial layer • The basal layer has straight arterioles where as the superficial layers has spiral ones – important in the process of shedding

23. Uterine Cycle – Proliferative Phase • Occurs during follicular phase of ovarian cycle • Endometrium exposed to oestrogen , regeneration from the last menstrual cycle occur • Glands in endometrium are straight in this phase, parallel to one another and contain little secretion

24. Uterine Cycle – Secretory Phase • After ovulation – progesterone production causes secretory changes in endometrial glands • Appearance of secretory vacuoles in glandular epithelium below nuclei • Secretions in lumen of glands which become tortuous and develop serrated margins

25. Uterine Cycle – Menstrual Phase • Luteal phase lasts 14 days – then there is a regression of corpus luteum → decline in oestrogen and progesterone • This leads to a intense spasmodic contraction of spiral section of endometrial arterioles → ischaemic necrosis → shedding of superficial layer → bleeding . • These spasms are associated with prostoglandin , which are also associated with increased uterine contractions during menstrual flow.

26. Cervical Mucus • Important to stop ascending infection • Changes during the menstrual cycle • Early follicular phase – viscid and impermeable • Late follicular phase – increasing oestrogen levels mucus becomes watery and easily penetrated, allowing spermatozoa to get through. Change is known as Spinnbarkheit • Post-ovulation – progesterone from corpus luteum counteracts oestrogens effects mucus becomes impermeable and the cervical os contracts

27. Other Changes • Body temperature – Rise of 0.5°C after ovulation till onset of menstruation. Due to progesterone levels. If conception occurs – this temperature is maintained throughout pregnancy • Breast changes – breast swelling during luteal phase due to increasing progesterone levels • Psychological changes – change in mood and an increase in emotional lability . Might be due to falling progesterone levels.

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