L8: Clinical overview of IVF Flashcards
1
Q
What percentage of IVF cycles fail for unknown reasons?
A
- ~40%
2
Q
4 male factors for infertility:
A
- Oligospermia
- Asthenospermia
- Teratospermia
- Azoospermia (obstructive or non-obstructive)
3
Q
Sources of sperm for IVF procedures:
A
- Ejaculate (can require electroejaculation in some nervous system conditions)
- PESA: Percutaneous epididymal sperm aspiration
- TESE: Testicular sperm extraction (surgical)
- Urine (in case of retrograde ejaculation; will require alkaline solution to be drunk, protecting sperm from acidic conditions)
4
Q
3 methods for sperm selection in IVF clinics:
A
- Density gradient (isolates highest quality sperm under centrifugation) aka sperm capacitation
- Microfluidics e.g. Zymot chip
- CASA -> computational quality assessment
- PICSI: Test of physiological binding capacity using hyaluronic acid
5
Q
What is the purpose of controlled ovarian hyperstimulation?
A
- Increases window through which FSH levels are high enough to stimulate progression to graafian follicles
- Improves chances of successful ovulation
6
Q
Consequences of over and understimulation of ovaries:
A
- Too low: anovulatory phenotype, no egg to collect
- Too high: Patient develops OHSS
7
Q
What is OHSS?
A
- Ovarian hyperstimulation syndrome
- Iatrogenic condition due to excess FSH stimulation
- Women will have excess follicles developing simultaneously, resulting in amplification of pregnancy symptoms
- e.g.: Fatigue, mood swings, nausea, cramps, can be fatal
8
Q
Mechanism behind OHSS:
A
- Large number of developing follicles -> FSH threshold reached very early
- Results in premature release of LH by pituitary gland (trying to ovulate)
- LH induces pregnancy side effects
9
Q
How can OHSS be managed/controlled:
A
- Prevent LH secretion upstream of pituitary (hypothalamus)
- GnRH antagonist: Blocks GnRH receptor with immediate suppression of LH
- GnRH agonist: Downregulates receptor, with initial LH flair followed by suppression
10
Q
What are the 4 stages in controlled ovarian hyperstimulation protocol?
A
- Choice of protocol
- Choice of dose (based on BMI, age, ovarian reserve based on baseline FSH level)
- Follicular monitoring (scans, serum oestrogen/progesterone)
- Triggering of ovulation -> induces nuclear maturation of egg into a haploid zygote, with half of genetic material ejected in polar body
11
Q
What are the criteria for egg collection? (x2)
A
- 3+ follicles over 17mm diameter
- 10,000 iu hCG
- -> Will then carry out trans-vaginal oocyte recovery after 36hrs (often under sedation)
12
Q
Broad outline of ART procedure:
A
- Ovarian stimulation and monitoring (2 weeks)
- Egg collection
- Insemination/ICSI
- Fertilisation check
- Embryo culture
- Embryo transfer
- Luteal support
- Pregnancy test
13
Q
Explain why day 3 embryos used to be implanted vs updated protocol:
A
- Historically used day 3 embryos, as technology to culture to blastocyst stage was lacking -> had to transfer more eggs at an earlier stage, increasing risk of multiple pregnancies and thus risking complications.
- Day 5 now used; they have better success as embryonic genomic division occurs in this window (d3 - 5) and will be aberrant in 50% of blastocysts (switches on metabolism due to depletion of maternal nutrient provision) -> acts to select out incompetent embryos
14
Q
Why will luteal support often be provided after embryo transfer?
A
- Exogenous progesterone supplements lost progesterone production capacity
- During collection procedure, some of corpus luteum will be excised due to suction, and the corpus luteum is essential for progesterone procedure up until the 12 week point where the placenta takes over
15
Q
Features of embryo transfer procedure and success rates:
A
- Abdominal USS guided
- Success often depends on operator experience due to sensitivity of technique
- Variety of catheters may be used depending on individual anatomy with no proven difference in efficacy
- Transferred 1 - 2cm from fundus
