Normal Menstrual Cycle

University:
Stanford University
Course:
PEDS 282 | Pregnancy, Birth, and Infancy
Academic year:

2023
Views:

73

Pages:

1
Author:

Pierre B

Normal Menstrual Cycle Fundamental to the menstrual cycle are: Intact hypothalamic-pituitary-ovarian axis Presence of responsive follicles in ovaries A functional uterus Patency of genital tract OVARIAN CYCLE UTERINE CYCLE Follicular phase Day 1-8 = high FSH & LH à development of follicle (10-20 develop, all bar 1 then undergo atresia) Proliferative phase (day 5-14) = oestrogen à proliferation. The glands are tubular & in a regular pattern, little secretion. Day 9-14 = developing follicle produces oestrogen (from granulosa cells), peaks 18 hrs prior to ovulation. As oestrogen rises the FSH & LH fall to prevent multiple follicles maturing Ovulation - Day 14 = rapid enlargement of follicle and rupture à release. Final rise in oestrodiol à FSH & LH surge (+ve feedback). Immediatley before ovulation oestrodiol falls & progesterone increases Secretory phase (day 14-23) = post ovulation the progesterone from the corpus luteum induces secretory changes in the endometrial glands (margins on glands appear serrated) Menstrual phase (day 1-5) = drop in progesterone as corpus luteum regresses à production of prostaglandins & vasospasm of spiral arteries à menstruation CERVICAL MUCUS Luteal Phase – Day 15-28 = corpus luteum à increase in progesterone & 2o rise in oestrodiol. Gonadotrophins remain low until regression of corpus luteum at day 26-28. Regression à progesterone drops à menstruation Early follicular phase = viscid & impermeable If fertilisation = trophopblast à produces gonadotrophins à maintains corpus luteum which maintains progesterone which maintains lining Luteal phase = progesterone from corpus luteum counteracts oestrogen à impermeable mucus Normal cycle 28 days (21-35) Predicatably regular Bleeding for 2-5 days Blood loss <80ml/month (40ml = average) No IMB Bleeds do not interfere with social/sex life/ADL Menorrhagia – regular heavy periods Metrorrhagia – eratic heavy bleeds Precocious puberty – before 8yrs Mitlesmirtz – mid cycle pain assoc with ovulation Late follicular phase = oestrogen à water content increases à easily permeated