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ELS/ALS Exam Review > Embryology > Flashcards

Embryology Flashcards

1
Q

What are seven pitfalls which must be identified and addressed during the embryo transfer process?

A
  1. Mucus within the cervical canal
  2. Atraumatic navigation of the cervical canal
  3. Location of embryo placement within the uterine cavity
  4. Embryo transfer catheter type
  5. Volume of transfer media
  6. Uterine contractions
  7. Other things
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2
Q

When was the first successful pregnancy after embryo transfer described?

A

1978

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3
Q

Why is cervical mucus a problem during embryo transfer and how can it be mitigated?

A

Studies show the presence of mucus inside the catheter drastically lowers pregnancy rates, and even mucus adherent to the outside of the catheter shows decreased rates when compared to catheters that were mucus free after the embryo transfer. This is because mucus within the cervical canal has the potential to plug the transfer catheter tip resulting in improper dispatching of the embryo into the uterine cavity.
Removal of the excel cervical mucus prior to embryo transfer is ideal.

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4
Q

If an outer sheath is used on a transfer catheter to navigate the cervical canal, it is important that it not pass what anatomical point and why?

A

The internal os of the cervix, as studies show that insertion beyond the internal os into the lower uterine segment decreases pregnancy rates.

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5
Q

How is ultrasound-guided embryo transfer accomplished?

A

By using the patient’s bladder as an acoustic window and directly visualizing the embryo transfer catheter as it enters the uterine cavity.

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6
Q

What three rates were higher in meta-analysis of ultrasound-guided embryo transfers vs. clinical touch transfers?

A
  1. Live birth rates
  2. Ongoing pregnancy rates
  3. Implantation rates
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7
Q

What three problems were found to be more common in clinical touch embryo transfers in comparison to ultrasound-guided ones?

A
  1. Instrumentation of the cervix (and subsequent trauma)
  2. Uterine contractions (also due to aforementioned trauma)
  3. Having a bloody catheter tip
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8
Q

Live birth rates and implantation rates favor the release of the embryo into what part/s vs. what part of the uterus?

A

Lower- to mid-uterine cavity release over uterine fundus release

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9
Q

Why is it important to avoid contact with the uterine funds during embryo transfer?

A

To decrease uterine contractility and to decrease the risk of ectopic pregnancy

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10
Q

Transferring an embryo too close to the internal cervical os can lead to what type of pregnancy?

A

Cervical ectopic

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11
Q

Increased uterine contractions following embryo transfer are associated with what and what is one study which shows this?

A

Decreased implantation rates; one study showed a three fold decrease in pregnancy rates when comparing less than 3 contractions per minute to greater than 5 contractions per minute.

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12
Q

What are three causes of contractions after embryo transfer?

A
  1. Cervical and uterine manipulation during speculum insertion,
  2. the use of a tenaculum instrument during difficult transfers,
  3. Undue contact between the transfer catheter and the endocervical canal and uterine myometrium
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13
Q

How can vigorous contractions after embryo transfer contribute to ectopic pregnancies?

A

As the contractions propel the embryo either upward or downward from its initial transfer location

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14
Q

How can vigorous contractions after embryo transfer contribute to ectopic pregnancies?

A

As the contractions propel the embryo either upward or downward from its initial transfer location

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15
Q

Studies have shown that, upon post-transfer microscopic examination of the embryo catheter (as well as the attached mucus and speculum), what percentage of embryos were extruded or not placed in the uterine cavity?

A

9%

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16
Q

What quality assurance is performed in the lab after embryo transfers?

A

Identification and documentation of blood and mucus on the embryo catheter

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17
Q

What should patients be told to expect after embryo transfers?

A

To expect intermittent uterine cramming and possible bloating

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18
Q

What symptom post-transfer requires patients to come back for further evaluation and what may it indicate?

A

Significant abdominal pain; this could be a symptom of OHSS, infection, and ovarian torsion (amongst other things)

19
Q

What are the three factors taken into consideration for the SART and ASRM transfer order guidelines?

A
  1. Patient age
  2. Cleavage stage vs. blastocyst stage transfer
  3. Embryo quality
20
Q

What four things must culture media be tested for?

A
  1. Osmolarity
  2. pH under working conditions
  3. Lack of endotoxin contamination
  4. Biocompatibility
21
Q

In what two ways do some (rare) clinics prepare their own media de novo?

A
  1. From pre-mixed media salts

2. From individual components

22
Q

What does pHi stand for?

A

Intracellular pH

23
Q

Early cleaving embryos both less than and greater than 8-cells have a pHi range of what, typically?

A

7.1-7.3

24
Q

What is the typical pH of commercial culture media?

A

7.4-7.5

25
Q

Studies of human oviductal fluid suggest that the pH is what?

A

7.3

26
Q

How can the CO2 be changed in the incubators to lower the pH?

A

Raise it

27
Q

What are the three types of media used in embryology labs?

A
  1. Bicarbonate buffers
  2. Non-bicarbonate buffers, like PBS (phosphate-buffered saline)
  3. Zwitterion buffering (HEPES and MOPS)
28
Q

What are four types of protein supplements that can be added to culture media?

A
  1. Serum albumin
  2. Prepared homologous serum, follicular fluid, donor serum, or fetal cord serum
  3. Albumin and macro globulin mixtures
  4. Recombinant human albumin
29
Q

Why should mineral oil not be autoclaved or heated in any fashion beyond the temperatures used for embryo culture?

A

For fear of generating further potentially toxic changes in the oil

30
Q

What is an important note of caution for mineral oil not labeled for use with human embryos?

A

There have been many anecdotal reports of fungal contamination via spore deposition into the culture media traced to specific lots of mineral oil, although mineral oil is inert, it obviously can act as a carrier for some microorganisms. Membrane filtration, although time consuming, can effectively sterilize mineral oil.

31
Q

How was fertilization achieved using traditional IVF?

A

Incubating ~100,000 sperm with each oocyte and leaving them for about 18 hours after the time when the oocytes would have been ovulated (oocytes were retrieved 36 hours after trigger and incubated alone for 4-6 hours prior to this)

32
Q

Why didn’t SUZI work well?

A

Acrosome-intact sperm swam around inside the zone pellucid and mostly failed to bind to the oolema to achieve fertilization

33
Q

Why didn’t Partial Zona Dissection (PZD) work well?

A

Sperm need to bind to, and pass through the zone in the normal fertilization process. Having a hole in the zone did not give reliable results.

34
Q

Where and when was ICSI developed?

A

Belgium, early 1990’s

35
Q

What is ROSNI and what are three reasons why it isn’t practiced any more?

A

Round Spermatid Injection with ICSI, failed due to:

  1. Technical difficulty of identifying round spermatids in fresh testicular biopsies
  2. The lack of a fully developed centriole in the cells
  3. Their inability to activate oocytes after injection
36
Q

What is one added benefit of PVP besides the obvious greater slow control?

A

Reduces sticking of the sperm cell to the glass

37
Q

Why is it necessary to swipe the tail of even immotile sperm during ICSI?

A

Because disruption of the sperm membrane is required for fertilization

38
Q

What is, arguably, the most difficult technical part of ICSI?

A

Successfully breaking the oolemma and getting the needle through the membrane

39
Q

What are four procedures used in conjunction with ICSI?

A
  1. Sperm procurement (from ejaculate, epididymis, testis)
  2. Sperm preparation (including using HOS or caffiene/pentoxyfilline)
  3. Sperm sélection (swimming and morphology)
  4. Oocyte activation (with globozoospermia patients, by chemically activating oocytes with calcium ionophore)
40
Q

What is globozoospermia?

A

Sperm lack normal acrosome structure (it’s a genetic defect that make the sperm heads look like lollipops) and function (can’t activate oocyte even after ICSI without the lab adding calcium ionophore)

41
Q

Why does training on one laser not qualify an embryologist to perform LAH or biopsy on another?

A

Because laser power is fixed but it varies among manufacturers (different software options complicate their use, but the pule duration needed to make a fixed size hole will vary based on the inherent power of the laser)

42
Q

What are two ways in which an embryologist may inadvertently cause damage to the remaining embryo during a biopsy?

A
  1. Using the laser indiscriminately

2. Aspirating cells with too much force

43
Q

What are five ways to artificially collapse an embryo?

A
  1. Laser-induced blastocyst collapse
  2. Collapsing the cavity with an ICSI needle
  3. Induced blastocyst collapse by pipetting
  4. Using osmotic pressure to collapse blastocysts
  5. Collapse during blastocyst biopsy

ELS/ALS Exam Review (7 decks)

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