ART Flashcards
What is infertility?
Infertility defined as the failure to conceive after 1 year of regular unprotected intercourse.
What are the causes of infertility - 1 in7 couples in the UK (4)
1)Mechanical blockage to egg and sperm meeting:
Infection/occlusion of vas deferens or uterine tubes.
Previous ligation for sterilisation.
Endometriosis.
Congenital defects.
2)Failure of gamete production or release:
Anovulation, maternal age, PCOS.
Azoospermia, asthenozoospermia, teratozoospermia.
3)Failure of fertilisation/implantation & miscarriage.
Genetic factors.
Endometrial receptivity, maternal age.
4)Unknown/unexplained.
Methods of Assisted Reproductive Technology (6)
Inducing ovulation with exogenous hormones.
By-passing the uterine tube (IVF).
Direct collection of sperm from the testis/epididymis.
Direct insertion of the sperm into the egg (ICSI).
Donor gametes.
Combination of the above.
Inducing ovulation - exogeneous gonadotrophins (3)
Used to treat women who are anovulatory or who have oligo/amenorrhoea.
The aim is to induce single dominant follicle.
Daily injections…monitor by ultrasound during the cycle. (LH +FSH)
Inducing ovulation by removing negative feedback (5)
Gonadotrophin levels may be normal, but are not cyclical.
Inter-cycle rise in FSH relies on death of the corpus luteum. ie. fall in levels of progesterone and estradiol.
There is no corpus luteum in the absence of ovulation
Cannot reduce progesterone as there has not been a corpus luteum to make any.
There are follicles in the ovary making estrogen so we can remove the negative feedback of this.
2 ways to remove estrogen feedback: (2)
- Block the E2 receptor on the pituitary gonadotroph cells with SERM: Clomid/Clomiphene.
- Stop E2 being made by using an aromatase inhibitor (no conversion from T to E2). Drugs ending in ‘zole’ eg. Letrozole.
IVF cycle outline (9)
1)Hypothalamic-pituitary downreg. (GnRH)
2)Ovarian stimulation with FSH (ultrasound monitoring)
3)hCG trigger
4)Oocyte retrieval
5)Fertilisation in vitro
6)Embryo culture 3 – 5 days
7)Embryo or Blastocyst Transfer
8)Pregnancy confirmation
9)Luteal phase support - Cyclogest (progesterone)
Why are the ovaries hyperstimulated during IVF?
As failure will occur at each stage (9), we require as many eggs as possible and so hyper-stimulate the ovaries to increase follicle numbers.
Multiple follicle selection with exogenous gonadotrophin explained (3)
1)there is no df selection = most/all follicles will survive
2) = >oestrogen production = ovulation (surpasses threshold)
3) prevention of LH surge to prevent ovulation
Explain how to conduct controlled ovarian stimulation (5)
1) Downreg. HPG axis using GnRH antagonist or agonist.
2) Give FSH by subcutaneous injection= Growth of multiple follicles.
3)Monitor follicle growth with ultrasound until most follicles 12–19mm.
4)At this point hCG trigger given (GnRH agonist or Kisspeptin may be used).
5) 36 hours allowed for completion of meiosis I and initiation of meiosis II before egg collection.
How does Oocyte Retrieval (34-38 hours post hCG trigger) occur?
Collect mature eggs from ovary using transvaginal needle aspiration under
ultrasound guidance .
How do you prepare sperm for IUI or IVF? (4)
1) collect semen and put into a solution w/ isotonic solution + centrifuge (x400 -5mins)
2) = will separate to give live sperm (motile fraction)
3) I egg + sperm in each bubble of media in petri dish (IVF)
or
directly inject sperm into uterus (IUI)
What are the control factors for IVF? (6)
nutrients, acidity, humidity, temperature, gas composition of air, and exposure to light.
Describe the incubation of the sperm + egg in IVF (3)
The sperm and the egg are incubated together at a ratio of about 75,000:1.
Duration of this co-incubation traditionally 16 – 18 hours .
Approximately 65% of the eggs will fertilize.
Embryo culture explained (3)
1) The fertilised egg has 2 pronuclei = 1st sign of fertilisation
2)The developing embryo contains 6-8 cells 3 days after fertilisation
3) Blastocyst 5 days old approximately 100 cells
