Contraception & Infertility Flashcards
What are the natural types of contraception used?
- abstinence
- coitus interruptus (withdrawal method)
- rhythm method: avoid intercourse during fertile period; assuming a regular 28 day cycle with ovulation occurring on day 14/15 with the fertile period occurring on days 7-16 of cycle
How does a vasectomy prevent pregnancy from occurring?
Divide vas deferens bilaterally
Prevents sperm from entering the ejaculate
note: ensure ejaculate is free of sperm by doing semen analysis a few months post-surgery
What are the barrier methods of contraception?
- condoms
- diaphragm: lies diagonally across cervix, holds sperm in acidic environment of vagina to reduce survival time (does not totally occlude passage of sperm)
- cap: fits across cervix
- spermicide (most effective when used in conjunction with other barrier methods)
What are the methods of contraception which prevent ovulation?
- combined oral contraceptive pill = oestrogen (loss of negative feedback —> no LH surge) + progesterone (inhibits follicular development)
- depot progesterone: 3 monthly progesterone injections —> negative feedback inhibits ovulation
- progesterone only pill (minipill): may inhibit ovulation
- progesterone implants (subcutaneous tissue of arm): may inhibit ovulation
- progesterone coils
note: progesterone also causes thickened “hostile” mucus in the cervix (particularly at low dose, e.g. progesterone implant & minipill)
How does female sterilisation prevent pregnancy?
Use clips/rings/ligation to occlude Fallopian tubes
note: 1/300-500 recanalisation chance —> risk of ectopic pregnancy
What forms of contraception inhibit implantation?
- hormonal contraception (progesterone) directly affects the receptivity of the endometrium and prevents the endometrium from being prepared for implantation (absence of corpus luteum)
- post-coital contraception = high dose combined OCP or progesterone-only pill given up to 72 hrs post-intercourse (may disrupt ovulation & luteal function)
- intra-uterine device (IUD) = may also be used as post-coital contraception up to 5 days after ovulation (inert, copper, progesterone impregnated); causes leucocytic activity of endometrium
Define infertility.
Failure to conceive within 1yr (~75% of young couples who have regular, unprotected sex conceive within 1yr)
Affects ~15% of couples
PRIMARY = no previous pregnancy
- ~30% of cases due to problem with male partner
SECONDARY = previous pregnancy (successful or not)
General causes:
- failure to ovulate ~28%
- Fallopian tube problems ~22%
- uterine problems ~11%
- cervical problems ~3%
What are some coital problems causing infertility?
Not having intercourse in a way which allows sperm to fertilise ovum e.g. not having unprotected vaginal sex
What are some factors which cause infertility by anovulation?
note: occasional anovulatory cycles are normal, especially at the extremes of reproductive life
Hypothalamus & GnRH = reduced GnRH due to hyperprolactinaemia, weight loss, exercise, stress
Pituitary, LH, FSH = pituitary tumours causing reduced LH & FSH, Sheehan’s syndrome (ischaemic necrosis of pituitary gland as a result of hypotensive shock due to haemorrhage at birth)
Ovary, oestrogen, progesterone = premature ovarian failure, menopause, radiotherapy/chemotherapy
Differentiate causes by measuring hormone levels:
- high LH & FSH and low oestrogen (lack of negative feedback by oestrogen means LH and FSH remain high) —> menopause/ovarian failure
- low LH & FSH and oestrogen (due to reduced production of LH & FSH) —> hypothalamic/pituitary feedback
Describe polycystic ovarian syndrome.
Disorder characterised by hyperandrogenism (causing hirsutism due to high testosterone) and ovarian dysfunction (polycystic ovaries)
- uncertain pathogenesis (?pituitary origin, ?ovarian origin)
- increased androgen production from thecal cells —> hirsutism, acne, weight gain, irregular cycles
- raised LH:FSH (positive feedback due to anovulation)
- insulin resistance
- multiple small ovarian cysts (form periphery of “pearls” on ovary); ovaries look like pre-pubertal ovaries
- anovulation —> amenorrhoea/oligomenorrhoea
- increased prevalence in SE Asians
- sustained oestrogen stimulation of endometrium —> increased risk of endometrial malignancy
Diagnostic criteria: 2 of out 3 of =
- history of irregular periods (2-6 month intervals)
- male pattern baldness/increased androgen
- ultrasound shows polycystic ovaries
note: follicles may still secrete inhibin —> reduction in FSH:LH
note: androgens may suppress LH surges
What drugs can be used to treat anovulation?
Anti-oestrogens e.g. tamoxifen, aromatase inhibitors, clomophine —> reduce negative feedback to hypothalamus & pituitary —> increased GnRH —> increased FSH —> increased oestrogen —> LH surge —> ovulation
Gonadotrophins e.g. FSH (IVF treatment)
GnRH agonists; pulsatile to mimic normal secretion (give in late puberty to increase height and reduce periods)
How can infertility result from tubal occlusion?
Sterilisation
Scarring from infection (e.g. chlamydia), endometriosis (lining of womb implants in the pelvis)
Diagnosis via laparoscopy & dye insuffation, hysterosapingogram (+ look for Fitz-Hugh-Curtis syndrome)
Treatment: tubal surgery (reanastomosis) - 50% success rate, assisted conception
How does abnormal sperm production result in infertility?
- abnormal production e.g. testicular disease
- obstruction of ducts e.g. infection, vasectomy (reversal success rate ~40%)
- hypothalamic/pituitary dysfunction —> azoospermia (give external FSH & LH)
- cystic fibrosis (congenital bilateral absence of vas deferens)
What are the main factors which cause infertility in women?
- defects of uterus/cervix e.g. fibroids, polyps
- hormone imbalances
- ovarian cysts/PCOS
- PID
- fibrosis (STD/endometriosis)
- tumour
- chronic disease e.g. diabetes
- autoimmune
- clotting disorders
- obesity
- poor nutrition/eating disorders
- medications/toxins
- heavy use of alcohol
Why is there an increased risk of endometrial malignancy in prolonged, untreated PCOS?
Increased testosterone is a risk factor for endometrial cancer
