What does the menstrual cycle involve?
The interaction of many endocrine glands, as well as a responsive uterus
What interacts in the menstrual cycle?
- The central nervous system; the hypothalamus and pituitary
- The ovaries
What does the interaction between the CNS and the ovaries result in?
Cyclic and ordered sloughing of the uterine endometrial lining
What are the key hormones in the control of the menstrual cycle?
- Gonadotrophin releasing hormone (GnRH)
- Follicle stimulating hormone (FSH)
- Luteinising hormone (LH)
What are the stages of the menstrual cycle?
- Proliferative stage
- Secretory phase
When does the proliferative stage of the menstrual cycle begin?
At the onset of menses
When does the proliferative phase end?
When ovulation takes place
What takes place during the proliferative phase of the menstrual cycle?
What happens in folliculogenesis?
A dominant follicle is selected from a pool of growing follicles that will be destined to ovulate
What does the growth of follicules during the proliferative stage depend on?
What does the growth of a follicle during the follicular phase lead to?
Production of estradiol from the layers of the granulosa cells surrounding it
What is estradiol responsible for in the proliferative phase?
The proliferation of the endometrial lining of the uterus
When does ovulation occur?
At the peak of follicular growth
What does ovulation occur in response to?
What size to follicles grow to prior to ovulation?
Sizes greater than 20mm in average diameter
By what mechanism is LH released following follicular growth?
In a positive feedback mechanism from the anterior pituitary, due to prolonged exposure to estradiol
What levels of estradiol are required for positive feedback to take place?
Above 200pg/mL for approximately 50 hours
What is required for the oocyte to be released from the follicle in ovulation?
Several proteolytic enzymes and prostaglandins are activated, leading to digestion of the follicle wall collagen
What happens once an oocyte has been released in ovulation?
The fallopian tube is responsible for picking it up to await fertilisation
What happens during the secretory phase?
The remaining granulosa cells that are not released within the oocyte during the ovulation process enlarge and acquire lutein
What colour is lutein?
What are the granulosa cells that have acquired lutein called?
What does the corpus luteum do?
Predominantly secretes progesterone
When is peak progesterone production noted?
1 week after ovulation takes place
What does the life span of the corpus luteum, and hence progesterone production, depend on?
Continued LH support from the anterior pituitary
What happen to the corpus luteum if pregnancy takes place?
hCG (human chorionic gonadotrophin) will maintain the corpus luteum
What happens to the corpus luteum if pregnancy fails to happen?
Luteolysis takes place, and the corpus luteum is converted to a white scar, the corpus albicans
Draw a diagram illustrating the blood supply of the endometrium
What happens to the radial arteries as menses occur?
They shrink and compress, so blood supply to the innermost layer of the womb is affected
What happens to the innermost layer of the womb after the radial arteries have been compressed?
It dies and gets sloughed off
How long does mensturation last?
24-32 days, but variable
When is regularity of menstruation best?
Between 20 and 40 years
How does the length of the menstrual cycle change depending on age?
- Longer in menarche
- Shorter in pre-menopause
What is the median blood loss per menstrual cycle?
When does most of the blood loss during menses occur?
In the first 48 hours
What % of women loose >80ml per cycle?
What % of those who loose >80ml/cycle are anaemic due to significant blood loss?
What is menorrhagia?
What are the causes of menorrhagia?
- Abnormal clotting
What are fibroids?
Benign growths found in the uterine cavity
What are fibroids often present with?
What can very large fibroids present as?
In what locations are fibroids found?
- Pedunculated (on a stalk)
What kind of cancer can cause heavy periods?
What is the problem with endometrial cancer?
Low detection rate
Why does endometrial cancer have a low detection rate?
- A lot of male doctors are reluctant to ask questions, or to follow up
- Political correctness
- Problems obtaining chaperones
How can endometrial cancer be detected?
- Ultrasound scan
- Pelvic MRI
What % of cases of heavy periods are caused by dysfunctional uterine bleeding?
What is dysfunctional uterine bleeding?
No recognisable pelvic pathology, pregnancy, or general bleeding disorders. No cause has been found to account for heavy periods
What may a person opt for in the case of dysfunctional uterine bleeding?
What can cause irregular bleeding?
When is bleeding between periods common with hormone contraceptives?
During the first three months
What hormonal contraceptives can lead to irregular bleeding?
- Combined oral contraceptive pill
- Progesterone only pill
Contraceptive patch (transdermal patch)
- Contraceptive implant or injection
- Intrauterine system (IUS)
Contraceptive patch (transdermal patch)
When are menstrual problems with hormone contraceptives possible?
- Missed combined pills/progesterone only pills
- If certain prescription medicines or St John's Wort are taken when using the pill, patch, ring, or implant
- When have vomiting/diarrhoea whilst on COCP
Why does missed combined pills/progesterone-only pills cause menstrual problems?
Disrupts control of periods
Why can vomiting/diarrhoea cause menstrual problems when taking the pill?
Causes a dip in hormone levels in the blood
How can heavy periods be treated?
Endometrial ablation of the endometrium
What happens in endometrial ablation of the endometrium?
Use a Nd-YAG laser to burn the lining of the endometrium to reduce the thickness of the layer
How effective is endometrial ablation of the endometrium?
Relatively good success rate. Sometimes works, sometimes needs repeating
What is amenorrhea?
What are the causes of amenorrhea?
What are the physical impacts of menstrual disorders?
What is the psyschological impact of menstrual disorders?
- Mood swings
What is the social impact of menstrual disorders?
Impact on ability to socialise/swim/perform sports