Embryo physiology, morphology and ET

Question 1

In vivo what temperature do embryos grow at?

Answer 1

37 degrees

Question 2

In vivo what pH do embryos grow at?

Answer 2

7.2-7.4

Question 3

In vivo what oxygen concentration do embryos grow at?

Answer 3

low

Question 4

In vivo what is the metabolic profile of the oviduct fluid which embryos develop in?

Answer 4

high pyruvate and lactate
low glucose

Question 5

In vivo what is the metabolic profile of the uterine fluid which embryos develop in?

Answer 5

high glucose
low pyruvate and lactate

Question 6

How is a good embryo measured?

Answer 6

through growth rate and morphology

Question 7

Morphology is an easy and quick assessment of predicting which embryos have the highest chance of resulting in pregnancy. However the method has its limitations, what are to consider in respect to morphology as a tool for determining a good embryo?

Answer 7

morphology and genetics are not well correlated

Morphological features have proven no biological significance

embryologists are not trying to make embryos better but just trying to not stress them out

Question 8

On a day 1 fertilisation check at 17 hpi, what are you looking for?

Answer 8

2 pronuclei (dents in the oocyte)

2 polar bodies

Question 9

On a day 1 fertilisation check at 23 hpi, what are you looking for?

Answer 9

0 pronuclei (only if two were seen at 17 hpi)

2 polar bodies

Question 10

On a day 2 fert check at 44 hpi, what do you expect to see?

Answer 10

4 cell

Question 11

When cleavage is occurring what factors are taken into consideration when grading?

Answer 11

cell number
- 2 cell, 4 cell or 8 cell
- what should it be for the time period you are checking?

Even or uneven cell numbers?
- we expect even numbers
- but cells do not cleave at the same time (a 3 cell with one large cell and two small may be just about to cleave and become a 4 cell vs 3 even cells which is not good as not showing signs of cleaving)

Fragmentation
- present or not present?
- high fragmentation is not good

Multinucleation
- seen through ‘dents’ in embryo
- more than one sperm has fertilized the egg

Question 12

On a day 3 fert check, 68 hpi, what do you expect to see?

Answer 12

8 cell

Question 13

In regard to in vivo development, what important changes are occurring between day 3 (8 cell) to day 4 (morula) that should be known when considering in vitro embryo culturing?

Answer 13

going from fallopian tube to uterus (important transition phase)

1. environmental changes
   - goes from high pyruvate to high glucose (changes metabolism to be equipped for glycolysis and higher energy is now needed)
2. embryo metabolism changes
   - fallopian tube: high pyruvate (embryo uses TCA metabolic pathway
   - uterus: high glucose (embryo uses glycolysis)
3. Embryo genetics change
   - before 8 cell: cell division controlled by maternal genome
   - at 8 cell stage: embryonic genome activation (EGA) under control of own genome for first time

Question 14

on a day 4 embryo check, 92 hpi, what do you expect to see?

Answer 14

Morula
- compaction of cells (as a result of EGA)
- single entity instead of discrete cells

Question 15

On a Day 5 embryo check, 116 HPI, what do you expect to see?

Answer 15

Blastocyst
- formation of 2 distinct cell types
— trophectoderm (edging cells - precursors for placenta)
— inner cell mass (ICM)

• blastocoel forms
  — fluid filled cavity ( seen by blurring)
• zona pellucida thinning and hatching

Question 16

If the clinic performs cultures to Day 7 on Day 6 what do you expect to see?

Answer 16

hatching blastocyst
- known as a zona breach when hatching

Question 17

What is the most common graded embryo used for embryo transfer (ET)?

Answer 17

Day 5 blastocyst stage

Question 18

During an ET where is the catheter placed?

Answer 18

about 1 cm from the fundus

Question 19

What are essential consideration for an embryologist during an ET procedure?

Answer 19

1. witnessing
   - must have independent witness checks to confirm patient matches embryo
2. speed
   - ambient conditions can easily stress embryo
   - need to show competency (1 minute to complete procedure from incubator to threading)
3. results
   - implantation rates need to be within 5% of clinic peers

Question 20

Why does the embryo and endometrium need to have synchronized development?

Answer 20

to ensure the embryo is introduced to the endometrium during the narrow window of receptivity so it can implant

Question 21

After an ET there is a two week wait for the beta hCG blood test. What factors are prioritized by the patient during this time?

Answer 21

progesterone
- luteal support and supports endometrial lining

pregnancy diet
- avoiding particular foods and taking vitamins

normal routine
- avoid vigorous exercise, hot baths and saunas

Question 21

Following the ET and 2 weeks wait, the patient receives a positive beta hCG test (YAY)! Why so they not take a regular urine pregnancy test?

Answer 21

With the antagonist cycle (most common) hCG can be used as a trigger and this would not have cleared her system yet. This could give a false positive read

Question 22

What occurs 7 week after ET if a patient has a positive beta hCG test 2 weeks after the ET?

Answer 22

An ultrasound to confirm if they are clinically pregnant
- heart beat?
- presence of sac?

Question 23

Once the patient is confirmed clinically pregnant what occurs next?

Answer 23

patient will leave the care of the IVF clinic to an OB
or
if their fertility dr is an OB their care will be transferred to the dr’s OB practice