Menstrual cycle

Genital cycle: ovarian, endometrial, cervical

Regulation of the cycle – hypothalamus-hypophysis-ovary axis

ovaries

In a young adult:
almond-shaped,
soild, greyish-pink,
approx. 3 cm long, 1.5 cm wide and 1 cm thick

Structure:
Central vascular medulla (loose connective tissue)
Outer cortex (thicker, denser than the medulla)
Tinca albuginea – condensed connective tissue
Covering – a single layer of cuboidal cells – germinal epithelium

Ovarian follicles:
They grow at an average rate of 2mm per day until they reach 20-25mm in diameter, just before ovulation

homones:

  • GnRH (gonadotropin release hormone)
    secreted from the hypothalamus
    GnRH stimulates pituitary to release FSH (follicle stimulating hormone) and LH (luteinizing hormone)
    LH is much more sensitive to changes in GnRH levels
  • FSH (follicle stimulating hormone)
    secreted by the anterior pituitary gland
    essential for follicular growth until the antrum develops
    secretion is highest and most critical during the first week of the follicular stage
    induces estrogen and progesterone secretion at the level of the ovary
    exerts negative feedback on GnRH secretion
    induces the proliferation of granulosa cells and expression of LH receptors on granulosa cells
  • LH (luteinizing hormone):
    secreted by the anterior pituitary gland
    required for both growth of preovulatory follicles and luteinization and ovulation of the dominant follicle
  • Estrogen
    for the development of the antrum and maturation of the Graafian follicle
    predominant at the end of the follicular phase
    Estradiol, the most potent and abundant estrogen
  • Progesterone
    secreted primarily by luteinized follicles
    levels increase just prior to ovulation and peak five to seven days post-ovulation
    During the luteal phase, progestins induce swelling and increased secretion of the endometrium

Follicular Development

  • At the beginning of each menstrual cycle, between 15 and 20 primordial follicles develop into primary follicles.
  • Under the influence of gonadotropins and ovarian hormones, primary follicles grow, only one primary follicle develops into a Graafian follicle and the remaining follicles undergo atresia.
  • The Graafian follicle is ovulated, expelling the oocyte and corona radiate into the peritoneum while the zona granulosa cells remain in the ovary.
  • The zona granulosa and surrounding theca cells develop into the corpus luteum, which in turn becomes atretic after 14 days.
  • After several months, the corpus luteum has fully devolved into the corpus albicans.

PHASES

  • Follicular (proliferative) phase:
    From the first day of menstruation to ovulation
    initiated by a rise in FSH levels at the first day of the cycle
    FSH stimulates the development of 15-20 follicles each month and stimulates follicular secretion of estradiol
    As estradiol levels increase under the influence of FSH, estradiol inhibits the secretion of FSH and FSH levels decrease.
    Estrogen levels peak towards the end of the follicular phase of the menstrual cycle.
    At this critical moment, estrogen exerts positive feedback on LH, generating a dramatic preovulatory LH surge.
  • Ovulation:
    LH surge  the primary oocyte enters the final stage of the first meiotic division and divides into a secondary oocyte and the first Barr body
    The oocyte adheres to the ovary
    muscular contractions of the fallopian tube bring the oocyte into contact with the tubal epithelium to initiate migration through the oviduct.
  • Luteal (secretory) phase:
    luteinization of the components of the follicle which were not ovulated
    LH surge  the granulosa cells, theca cells, and some surrounding connective tissue are all converted into the corpus luteum, which eventually undergoes atresia
    High progesterone levels exert negative feedback on GnRH
    As GnRH pulse frequency decreases, FSH and LH secretion also decreases
    Lacking stimulation by FSH and LH, after 14 days corpus luteum undergoes atresia and begins evolving into the corpus albicans.

Uterine Endometrial Cycle

  • Follicular Phase:
    increasing levels of estrogen
    --> proliferation of the functionalis from stem cells of the basalis,
    --> proliferation of endometrial glands
    --> proliferation of stromal connective tissue.
  • Luteal Phase or secretory phase:
    progesterone induces the endometrial glands to secrete substances – they become tortuous and have large lumens
    endometrium undergoes involution:
    days 25-26 of the menstrual cycle  vasoconstriction of the spiral arteries
    ischemia may cause some early menstrual cramps
  • Menstrual Phase:
    the spiral arteries rupture secondary to ischemia, releasing blood into the uterus, and the apoptosed endometrium is sloughed off
    lasts four days
    the functionalis is completely shed

contraception

Oral Contraceptives: the Pill

Mechanism:
Suppresses ovulation
Thickens cervical mucus
Thins endometrium
Slows tubal motility

ADVANTAGES
Regulates menses
Decreases blood loss/ menstrual cramps
No disruption at time of intercourse
Decrease risk of ovarian/endometrial cancer
Treatment for acne

DISADVANTAGES
Mood Changes, depression, anxiety
Daily pill taking may be stressful
No Protection against STI (Sexually Transmitted Infections), including HIV
Nausea, breast tenderness, especially in the first few cycles
Weight gain

Evra: The Patch

Description:
Estrogen and Progestin
1 Patch a week, for 3 weeks
4th week patch free, Menstruation
Usually worn lower abdomen or buttocks

Mechanism:
Prevents pregnancy in the same way that oral contraceptives

Advantages:
Menstrual (Similar to the Pills)
Nothing to do on a daily basis
No disruption at time of intercourse

Disadvantages:
Mood Changes, depression, anxiety
No Protection against STI (Sexually Transmitted Infections), including HIV
Nausea, breast tenderness, especially in the first few cycles
Weight gain
Cannot use if breastfeeding

Nuva Ring: the Ring

Combined estrogen and progestin
Thin flexible transparent ring
Left in place in the vagina for three weeks and removed for a week to allow a menstrual period the fourth week.
Maintains a steady low 
release rate while in place.

Suppresses ovulation
Similar to combined pills

Advantages:
Only TWO TASKS:
Insertion/Removal 1x month
Steady even hormonal levels in blood are achieved
Privacy/No visible patch or pill packages
95% of women say they cannot feel device

Disadvantages:
Some women dislike placing/removing objects into/out of their vagina
Adverse side effects similar to the pill
Possible devise expulsion

Depo Provera “The Shot”

Injected intra-muscularly into the deltoid or gluteus-maximums every 11 to 13 weeks.
Progestin only

  • Suppresses Ovulation
  • Thickens cervical mucus
  • Slows tubal and endometrial mobility
  • Advantages:
    Less menstrual blood loss and anemia
    After one year 50% of users will develop amenorrhea
    80% will develop amenorrhea in 5 years
    Only need to remember 1x every three months
  • Disadvantages:
    Irregular menses during first several months
    Unpredictable spotting and bleeding
    Possible weight gain: Progressive-Significant (5.4 1st year, after 5 years 16.5)
    Patient fear of pregnancy or build up of menses in uterus if not explained well
    Decreased libido
    Fear of needles
    Return to fertility is long average 10 months from last injection

Intrauterine Device “IUD”

  • T-shaped device with two flexible arms that bend down for insertion but open into the uterus.
  • Two straw-colored strings protrude through the cervix into the 
vaginal canal
  • Mechanism: CopperT
    Works by preventing fertilization
    Works primarily as a spermicide,Copper ions inhibit sperm motility so they rarely reach the tube
  • Mechanism: Mirena
    Progestin Only
    Causes cervical mucus to become thicker then by preventing sperm from moving up the reproductive track
    Prevents implantation

Copper-T

Advantages:
Effective long term (10 years) contraception from a single decision.
Requires no action at time of intercourse
Cost effective
Rapid return to fertility
Good option for women who cannot use hormones
95% user satisfaction, the highest of any other contraceptive currently begin used by women.

Disadvantages:
Blood loss during menstruation increased by 35% and increase cramping
Must check strings monthly after menstruation
Requires office procedure for insertion and removal, can be uncomfortable
Increase risk of infection PID
Uterine perforation
May be expelled

Mirena

  • Advantages:
    After 3-4 months it decreases menstrual blood loss more than 70%
    Amenorrhea: 20% by 1 year, 60% by 5 years
    Reduced risk PID, ectopic pregnancy by 60%
    As effective, or more effective than female sterilization
    Long lasting method, up to 5 years
    Immediate return to fertility
  • Disadvantages:
    Possible expulsion
    Acne, Headaches, discomfort after insertion or removal
    Risk of PID increased
    Ovarian cysts, most regress spontaneously

Implanon

Progestin only
Thin, flexible, plastic implant about the size of a matchstick.
Inserted under the skin by the bicep muscle.
Implanted in the arm for
3 years.

  • Mechanism:
    Constantly releases progestin into the bloodstream
    Suppresses ovulation
    Thickens the cervical mucus
  • Advantages:
    Insertion only takes a few minutes
    Protection against pregnancy is immediate if you get the implant during the 1st five days of your period
    Ability to get pregnant is immediate after removal
    Gives continuous long-lasting birth control without sterilization
    No medicine to take every day
  • Disadvantages:
    Irregular bleeding is the most common side effect
    Periods become lighter and may stop altogether or periods may become heavier and last longer
    Some women will have longer heavier periods
    Acne, change in appetite, or sex drive
    Pain at the site of insertion

Non-Prescription Methods

Female Condom
Male Condom
Spermicidal Foam
Spermicidal Film
Natural Family Planning
Abstinence