Contraception Flashcards
What is the role of oestrogen in the menstrual cycle in the early/middle follicular phase, before ovulation?
It has a negative effect on the anterior pituitary and hypothalamus, thus producing negative feedback
What else has a negative effect on the anterior pituitary during the early/middle follicular phase?
Inhibin
What is the role of oestrogen at ovulation?
It has a positive effect on the hypothalamus and anterior pituitary, causing the LH surge
What dose is progesterone at in the early/middle follicular phase (before ovulation)?
Moderate/high doses
What does progesterone do at moderate/high doses in the early/middle follicular phase?
Enhances the negative feedback of natural oestrogen, reducing LH and FSH secretion
What does progesterone do at moderate/high doses during ovulation?
Inhibits positive feedback of oestrogen, so no LH surge, so no ovualtion
What does progesterone do at lower doses during ovulation?
Does not inhibit LH surge, so ovulation still likely, but will thicken cervical mucus
What are the common methods of contraception?
- Natural
- Barrier
- Prevention of ovulation
- Inhibition of sperm transport
- Inhibition of implantation
- Sterilisation
What are the natural methods of contraception?
- Fertility awareness methods
- Lactational amenorrohea method
What happens in fertility awareness methods?
Use of fertility indicators to identify fertile and infertile points of the menstrual cycle
What are the fertility awareness methods of contraception?
- Cervical secretions
- Basal body temperature
- Length of menstrual cycle
What is the lactionional amenorrhoea method of contraception?
Breastfeeding delays the return of ovulation after childbirth
How long is the lactational amenorrhoea method effective for?
Up to 6 months after giving birth
What are the advantages of natural contraception methods?
- No hormones
- No contraindications
What are the disadvantages of natural contraception methods?
- Not as effective
- Unreliable
What is barrier contraception?
A physical barrier that prevents entrance of sperm into cervix
Give 2 examples of barrier contraception
- Male/female condoms
- Female diaphragm/cap
What are the advantages of condoms?
Can help prevent STIs
What are the disadvantages of male condoms?
Sensitivity/allergy to latex
What are the disadvantages of female condoms?
Not as widely available
What are female diaphragms/caps also used with?
Spermicide
What are the advantages of female diaphragms/caps?
Can be inserted anytime, so additional chemical barrier
What are the disadvantages of female diaghragms/caps?
Need to use with spermicide, which can cause local reaction
What methods of contraception prevent ovulation?
- Combined oral contraceptive pill
- Progesterone depot
- Progesterone implant
How can progesterone prevent ovulation?
At moderate/high doses, it inhibits the positive feedback of oestrogen, so no LH surge, so no ovulation
What does the combined oral contraceptive pill (COCP) contain?
Combination of oestrogen and progesterone
When is the COCP taken?
Either for 21 days, followed by 7 day break, or 28 days with 7 days of ‘dummy’ pill
What is the principal action of the COCP?
To prevent ovulation
What is the secondary action of the COCP?
- Reduced endometrial receptivitiy to inhibit implantation
- Thickens cervical mucus to inhibit penetration of sperm
What are the advantages of COCP?
- Can relieve menstrual disorders
- Reduces risk of ovarian cysts and cancer
What are the disadvantages of the COCP?
- User dependant
- Side effects
- Increases risk of certain conditions
What are the side effects of COCP?
- Breakthough bleeding
- Breast tenderness
- Mood disturbance
What does COCP increase the risk of?
- Venous thromboembolism
- Myocardial infarction
What is in a prosterone depot?
Synthetic progesteron
How is a progesterone depot administered?
Via subcutaneous/intramuscular injection, which is slowly released into the systemic circulation
How long does a progesteron depot last?
8-13 weeks
What is the principle action of a progesteron depot?
Prevent ovulation
What are the secondary actions of progesterone depots?
- Thickens cervical mucus to inhibit penetration of sperm
- Reduces endometrial receptivity to inhibit implantation
What are the advantages of a progesterone depot?
- Convenient
- Can relieve menstrual disorders
What are the disadvantages of a progesterone depot?
- Altered and irregular bleeding is common
- Delayed return of fertility for up to 1 year after stopping
- Not quickly reversible
- Small loss of bone mineral density, and possible increase fracture risk
What is a progesterone implant?
A progesterone containing 4cm flexible rod implant that is inserted sub-dermally in upper arm
How long does the progesterone implant work for?
Can work for up to 3 years
What is the principle action of the progesterone implant?
Prevent ovulation
What are the secondary actions of the progesterone implant?
- Reduce endometrial receptivity to inhibit implantation
- Thickens cervical mucus to inhibit penetration of sperm
What are the advantages of the progesterone implant?
- Long duration of action
- Convenient
- Can relieve menstrual disorders
What are the disadvantages of the progesterone implant?
- Small procedure required to fit and remove the implant
- Local adverse effects can occur
- Can cause changes in bleeding pattern
What methods of contraception inhibit sperm transport?
- Progesterone only pill
- Secondary action of other contraceptives
What will progesterone do at lower doses?
Does not inhibit the LH surge, so ovulation still likely, but will thicken cervical mucus
How does the progesterone only pill compare to other contraceptive methods?
It has a lower dose of progesterone
What does the progesterone only pill do?
Thickens the cervical mucus, making it impenetrable to sperm
What are the advantages of the progesterone only pill?
Can be used where the COCP is contraindicated
What are the disadvantages of the progesterone only pill?
- Menstrual problems are common
- Must be taken at the same time each day
What is the error for forgotton progesterone only pill?
Only 3 hours late
What contraceptive methods is inhibition of sperm transport a secondary action of?
- COCP
- Progesterone depot
- Progesterone implant
- Intrauterine system
What methods of contraception inhibit implantation?
Intrauterine device
What is a intrauterine device?
A small device made of plastic with added copper that is placed in the uterus
What is the principal action of an intrauterine device?
Copper is toxic to sperm and ovum, which prevents fertilisation
What are the secondary actions of an intrauterine device?
- Convenient
- Long duration of action
- Emergency contraception
How long does an intrauterine device last?
5-10 years
When can an intrauterine device be used as emergency contraception?
Up to 5 days after unprotected intercourse
What are the disadvantages of an interuterine device?
- Insertion may be unpleasant
- IUD displacement/expulsion may occur
- Periods may be heavier, longer, and more painful
- Risk of uterine perforation is 2/1000 insertions
What is the male sterilisation procedure called?
Vasectomy
What happens in a vasectomy?
Vas deferens are interrupted to prevent sperm entering the ejaculate. Done under local anaesthetic
What much be done after a vasectomy?
Must conform success by post-operative semen analysis to confirm no sperm in the ejaculate
When is a post-vasectomy semen analysis done?
12-16 weeks after surgery
What are the advantages of a vasectomy?
- Pernament
- No hormonal side effects
What are the disadvantages of a vasectomy?
- Failure rate 1/2000
- Should not be done if any doubt about having chidren in the future
What is the female sterilisation procedure?
Tubal ligation/clipping
What happens in tubal ligation/clipping?
Fallopian tubes are cut or blocked to stop the ovum travelling down from the ovary to the uterus. Done under local or general anasthetic
What are the advantages of tubal ligation/clipping?
- Permanent
- No hormonal side effects
What are the disadvantages of tubal ligation/clipping?
- Failure rate 2-5/1000
- Should not be chosen if any doubt about having children in the future