Understanding your embryology report

Understanding your embryology report

You have just completed your IVF cycle and the clinic has handed over your embryology report to you, in case you haven’t received it please request them for the report as it is your right to know and save for your own personal record. We agree, we all are in the age of technology but trust us when we say that google might not be able to assist you satisfactorily in decoding your embryology report. Try to google “Injected oocyte” and it will display an array of results which are not just limited to IVF. Asking around may confuse you more, so why not ask the very people who made the report. Yes, you guessed it correctly that is us, your embryologist.

The embryology report will have multiple parameters involving the egg, sperm and embryo along with what is transferred and vitrified. Through this article, we will try an explain how a report looks and how to make sense of it, to give you more control over your treatment cycle.

After your IVF cycle, depending on the type of treatment you may receive one of the following reports: 

1. IVF summary – From egg collection to the fate of embryos (Transferred or Vitrified)

2.  Frozen embryo transfer (FET)

3. Oocyte freezing report

IVF summary

An IVF summary is handed over after an ICSI or insemination cycle. It will include detailed information from number of eggs retrieved or received (in case of donor eggs) uptil the number of embryos transferred or frozen. It will also have  documentation about number of embryos remaining in cryostorage after a possible transfer.

We are highlighting some of the important parameters. Remember the layout of reports may vary from clinic to clinic, however the headers will remain the same.

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Basic information

The report will begin with basic information like partner name, Age, Date of egg collection and so on, review the information carefully and inform the clinic in case of any discrepancy.

Gametes – Egg and sperm 

The report will begin with number of eggs retrieved, what proportion of it was mature and number used for ICSI. There will also be detailed analysis of the sperm parameters.

Egg or oocyte 

Knowing the number of eggs retrieved Is important, since you can correlate that with the number of eggs expected. Your clinician during the last scan (before egg collection) will give you an indication regarding the number of eggs expected. Sometimes the expected and retrieved numbers don’t match and knowing this detail will help you in discussing the possibilities. Along, with the number retrieved, the report will also give an indication regarding the number of mature or MII and the fate of the remaining eggs or oocytes. Immature oocytes are referred as GV or MI and they are not used for injection. Only MII oocytes are used for ICSI.

Sperm

This section will always indicate the sperm parameters which were used on the day of procedure. It can fresh or frozen semen and the same will be mentioned. In case of unexpected embryo development this will help to determine the quality of the sperm. Remember, there is always a slight variance in sperm parameters and no two ejaculates are the same. Hence, documentation is always important to analyze and refer at a later stage.

Embryos

This is one of the most important sections in your report, it begins with Number of ooctes fertilized. Remember, only mature eggs are injected and now we are checking for how many oocytes have activated or fertilized after we have injected the sperm inside them. Normal fertilization is characterized by 2PN and 3PN and 1PN are not usable and discarded. In a good prognosis patient, we see a fertilization rate of 70%.

Let’s look at our sample report for more clarity. Here, our of 29 MII that were injected 25 were normally fertilized. This is a fertilization rate of 86%, which is above average.

  • Fertilization rate can be lower or higher that 70%, this rate is dependent on various factors like sperm parameters, Low ovarian reserve, PCOS and so on. In IVF, no two cases are same so don’t worry If your outcome is different.
  • The report will move on to number of embryos transferred. This category will indicate the number of embryo transferred, day of embryo development and the grade. In this case, there was no transfer in the same cycle and it was indicated as N.A.

The account for number of embryos vitrified is extremely important in any IVF summary. This category will indicate number of embryos cryopreserved, day of embryo development and the number of embryos per cryo device. Knowing the number of embryos frozen per cryo device is crucial and helps in planning of the next cycle. In the case of our sample report we can see 15 embryos were cryopreserved in 7 straws or cryodevice. If, you look closely you can even see the number of embryos cryopreserved per straw.

Having this information is empowering, looking at it you can decide with your clinican whether you want to use the straw with one emebryo or two. It enables you to take a more informed decision.

Frozen embryo transfer (FET) 

FET reports are usually an add on report to your IVF summary. For instance, you have undergone an egg retrieval, made embryos and frozen them. Now is the time to use them, your clinic will thaw the embryos (bring them back to 37 degrees Celsius) and place them in your “prepared” uterus. Hence, this report is an indication of what was thawed – transferred and an account of if, any embryos are remaining in cryostorage.

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Start with checking the basic information like Name and age. This report is less complicated and has two main aspects:

Embryo transfer date and embryos

This will indicate the date of transfer, number of embryos transferred. Both very simple to understand. Let’s, look at the sample report.

In the above report, the date of embryo transfer is mentioned 7/11/2020. This is the date of your procedure, the date to perform the pregnancy test will be calculated from this date. Next, to the date the number of embryos and the grades are also mentioned. We have thawed 2 embryos of grades 4BB, 5BB and they were transferred.

It is important to know the number of embryos that were thawed and transferred. As per good practice recommended globally, no more than 2 good grade embryos should be transferred. This is also partly the reason why not more than 2 blastocysts are frozen on 1 cryo device. If more than 2 embryos have been transferred, please speak to your clinician and understand the reasons, implications and risks associated with this decision. Ideally the number of embryos to be transferred should be discussed with your clinician before the procedure.

Remaining embryos in cryo-storage

This is very critical information as it gives an indication of the number of embryos which are remaining in cryo-storage. If, we look at the sample report it is indicated that there is one straw with two blastocyst stage embryos remaining.

It is always a good idea to do that math, for instance if your IVF summary mentions ten embryos were vitrified and you have transferred two in your FET cycle. Your FET report should mention that eight are still in cryostorage. If, the information is not matching it is always a good idea to speak to the clinic and get It clarified.

Oocyte/Egg freezing report

Last but not the least is the oocyte freezing report. This report will not be as detailed as the IVF summary report, it will focus only on the oocyte and have no mention of the semen parameters. Oocyte vitrification is usually done in cases of fertility preservation or in rare scenarios when the husband is not available or able to produce sperm on the day of the procedure.

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The main aspects of this report are:

Basic credentials like the name, age and date of freezing

Detailed information regarding oocytes

Number of oocytes retrieved, plays an important role for you to know what was expected as against what is retrieved. This is important as only a proportion of retrieved oocytes will be mature (MII) and only MII oocytes will be vitrified. If, we look at the sample report seven oocytes were retrieved, 4 were mature (MII) and the remaining three were GV which were discarded. The report also indicates that 4MII were vitrified on two straws

Freezing/vitrification details

After assessment of mature oocytes (MII), the next step is understanding how they were vitrified – How many per cryodevice. Remember, the total number of oocytes vitrified should always add up to the number of mature oocytes(MII). As per good practice, no more than four oocytes should be vitrified per cryodevice. In this case 2MII were frozen per cryodevice making it a total of 4 MII on two cryodevice.  This combination may change depending on the number of MII available to vitrify.

Oocyte freezing is usually long term freezing and Hence, in our opinion it is imperative to have a report for this procedure for your record and safe keeping.

Frequently Asked Questions :

  1. My report apart from MI, MII and GV has a column which reads as “other”, What is that?

There are two more categories of oocytes, which are not injected or used. These are Atretic and Empty zona (EZ). Atretic oocytes are degenerated and do not have a defined cellular wall, these cannot be used as they are not viable. Empty zona is a rare occurrence wherein there is no cytoplasm within the zona. Hence, the name empty zona. These oocytes cannot be used as they do not have any genetic material.

2. Why are MI or GV oocytes not injected or used?

For an egg to be considered normal, it needs to have 23 chromosomes which are present in the Metaphase stage(MII) of the oocyte development. When a sperm is injected it has an additional 23 chromosomes making the balance of the zygotes as 46 or 23 pair of chromosome. The chromosome number in Metaphase 1(MI) or Germinal vesicle(GV) stage are not 23 chromosomes. Hence, if you inject a sperm in MI or GV the chromosome balance becomes unstable and even though that oocyte gets activated (fertilise) it is still considered as abnormal.

3. My clinic did not provide me an embryology report, what should i do?

Having a written report of your treatment is your right, you need to have it for your records. Also, it is important to have a report because if you visit another clinic, having your cycle history is a good record for them to evaluate your case.

4. Why does an oocyte fertilise abnormally 1PN or 3PN?

Normal or abnormal fertilisation depends on the internal make up and mechanism of your gametes (Sperm and Egg). An oocyte may have three PN for two reasons 1. Two sperms entered the Oocyte, maybe during the time of injection or insemination 2. Three PN is usually attributed to some abnormality in the oocyte. When an oocyte fertilises with 1 PN it is usually due to some problem in the sperm. There are several studies which have made this claim, but more evidence is needed to be 100% sure. It is important to note that anything other than 2PN should not be used.

5. Why are only MII oocytes frozen during my oocyte freezing cycle.

Its because of the same reason explained in Q2. Only MII oocytes should be injected so why freeze MI are GV as they would anyways be discarded on thawing.

6. My doctor told me I have two embryos vitrified on one straw, but I want to transfer only one. what should i do?

Embryos once frozen on the straw cannot be separated. Therefore, it is very important to discuss your views with your doctor during your treatment cycle. If, it was discussed the doctor would have directed the embryologist to freeze the embryos separately. However, going forward there are two options 1. Discuss the grades with your embryologist and decide to transfer two embryos OR, 2. After thawing, transfer one embryo and refreeze the other for a later cycle. (Refreezing is a possibility, but it is important to understand the risks associated with it)

7. The number of oocytes retrieved and the number “used” don’t add up. What should I do?

Not all oocytes that are retrieved, will be used for injection as not all oocytes may be MII. But, it is important for you to the math, there should be accountability of all the oocytes whether mature or immature, usable or not usable. They are your genetic material and you should know their fate. For Example: Number of oocytes retrieved : 10, Number injected(MII) : 6 (This is an incomplete report). Number of oocytes retrieved : 10, Number injected(MII) : 6, GV: 1, MI: 2, Atretic : 1 (This is a complete report as there is an accountability of each oocyte). Same should be case for embryos, the fate of each embryo should be mentioned in the report.

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