Dr. Sai, Senior Embryologist , Malpani Infertility Clinic Pvt. Ltd.
While most infertile patients know quite a lot about their scans and medications, most are very poorly informed about what happens in the IVF lab ! At Malpani Infertility Clinic, we show all our IVF patients their embryos before transferring them. There are lots of questions patients ask me.
Here are some of the common questions, and their answers.
How do you grade embryos ?
This depends upon which Day we grade them.
- On Day 2 and 3 - Grading Multicellular Stage Embryos :
We grade the embryos as A, B, C, D ("A" being the best and "D" being the worst)
There are 3 factors which are considered.
- Embryos should be at 2 to 4 cells at 48 hours after egg retrieval (Day 2 embryos) and preferably about 6 to 10 cells by 72 hours (Day 3 embryos). These cells in the embryo are referred to as "blastomeres"
2-Cell (Day 2 embryo) 4-Cell (Day 2 embryo)
6-Cell (Day 3 Embryo) 10-Cell (Day 3 Embryo)
Cell regularity - degree of regularity of size of blastomeres
- It is generally best if the size of the individual cells (the blastomeres) are similar in size.
- If they are not, it is better if they are close to the same size, as compared to very different in size.
- A Grade A embryo is one which has equal sized cells in it.
4-Cell Embryo with Blastomeres of unequal sizes. This is Grade B embryo
Degree of fragmentation
- Fragmentation, is a process where portions of the embryo's cells have broken off and are now separate from the nucleated portion of the cell.
- A grade A embryo is the one which has no fragmentation or less than 10% fragmentation.
GRADE A :
10-Cell Grade A embryo
- Regular Blastomeres.
- No Fragmentation.
GRADE B :
10-Cell Grade B embryo
- Regular Blastomeres.
- > 10 % Fragmentation.
GRADE C :
8-Cell Grade C embryo
- Irregular Blastomeres.
- > 10 % Fragmentation.
GRADE D :
8-Cell Grade D embryo
- Irregular Blastomeres.
- > 20 % Fragmentation.
Do remember that a Grade C embryo does not mean that the baby will be abnormal ! It just means that the chances of implantation are reduced, as compared with a Grade A embryo. Fragmentation in human embryos is quite common and many beautiful babies have been born even after transferring embryos with fragments !
Grading Blastocyst Stage embryos (Day 5, Day 6 embryos) :
- By Day 5 , the embryo is called a blastocyst . It is now a hollow ball of cells.
A Blastocyst is graded considering 3 factors :
- Size of the Cavity ( blastocele) , Expansion and Hatching status.
- Inner Cell Mass (ICM) Quality.
- Trophectoderm (TE) Quality.
Inner Cell mass is marked as "ICM"
The cavity is Marked as "C"
Torphectoderm is Marked as "T" Early Blastocysts
- Cavity is very small or fills less than half the embryo's volume.
- The grade for Cavity in Early Blastocysts will be 1.
- The Grade for Early Blastocyst generally will be 1AA, 1AB, 1BA ..........
- The Cavity fills more than half the embryo's volume or completely fills the embryo's volume.
- The Grade for Cavity in Intermediate Blastocysts will be 2 or 3.
- The Grade for Intermediate Blastocysts generally will be 2AA, 2AB...... or 3AA, 3AB.........
- The Embryo Expands and the cavity completely fills the Embryo's volume.
- The Grade for Embryo will be 4.
- The Grade for Expanded Blastocysts generally will be 4AA, 4AB, 4BB..........
- When the embryo hatches , it comes out of its shell called the zona.
- The Grade for Embryo will be 5
- The Grade for Hatching Blastocyst generally will be 5AA, 5AB.............
Completely Hatched Blastocysts
- The embryo comes out completely from the zona.
- The grade for this embryo is 6.
- The grade for Hatched Blastocyst generally will be 6AA, 6AB.............
How many embryos do you transfer ?
We usually transfer 3 embryos on Day 3 . We try to individualise this for each patient, taking into account many variables , such as:
- Patient's Age - for less than 30 - 3. More than 35 - 4
- Previous History - 1 embryo is added more for every failed cycle.
Day of Transfer -
- Day 2- 4 embryos ( 4-Cell Grade-A) are transferred.
- Day 3- 3 embryos ( 8-Cell Grade-A)are transferred.
- Day 5- 2 Embryos are transferred.
- Embryo quality - These numbers apply to Grade A embryos only
Why is my embryo quality bad?
Ans: Embryo quality depends on 3 factors, Sperm; Egg ; and Lab conditions. If other patient's embryos are of good quality, then we can't blame Lab conditions for poor quality embryos . It is usually poor egg quality which is responsible for poor embryos. Poor sperm do not affect embryo quality ICSI is done
Why do some embryos grow slowly ? What are the chances of a pregnancy with slow growing embryos?
Ans: In each batch of embryos, some will be healthy and others will be unhealthy. It's impossible to predict this in advance. Embryos which grow slowly can still become a baby, but the chances are less, as compared to rapidly dividing embryos.
Why is my fertilization rate poor?
- If the fertilization rate is poor after IVF, this usually suggests sperm dysfunction. The best way of correcting this is to do an ICSI in the next treatment cycle
- If the fertilization is poor after ICSI, this usually suggests poor egg quality . Sperm quality should not affect fertilization rate after ICSI.
If the embryo Quality is bad, what are the chances of pregnancy?
Ans: Even poor quality embryos can become a healthy baby. However, the probability for implantation is lesser , as compared to good quality embryo.
Why not transfer all 6 embryos ?
Ans: This is because the chances of a high order multiple pregnancy are very high. More is not always better ! Transferring more than 3 embryos just increases the risk of a multiple pregnancy, without improving the chances of success. This is especially true if the patient is young; and the embryos are Grade A.
Does Day 5/6 Embryo Transfer (Blastocyst) help increase the chances of pregnancy?
Ans: No. Blastocyst transfer doesn't increase Pregnancy rate. However, it does allow us to select the best quality embryos, because we allow the embryos to compete amongst themselves, and then choose the best. Thus, it enables us to transfer fewer embryos as compared to a Day 2/3 transfer, thereby reducing the chances of a multiple pregnancy.
Will sequential embryo transfer help increase chances of pregnancy ?
Ans: Yes. Sequential Embryo transfer does help increase pregnancy rate. But it also increases the chances of multiple pregnancy. This is why very few clinics offer this.
How do you ensure that the eggs and sperms of different patients don't get mixed up?
Ans: Each and every biological cell is labeled with the patient's name. For example,
1) The Container for Semen collection is labeled with both Husband and wife's name before it is given to the patients.
2) The dishes in which the eggs and embryos are kept are labeled with the patient's name.
3) The Incubator chambers are labeled with the patient's name. The labels are discarded once the patient's embryo transfer is over.
4) The Nurse witnesses the procedure while the embryologist loads the embryos and hands over the catheter to doctor for transfer.
How long can we store the embryos once we freeze them ?
Ans: There is no time limit for storage of frozen embryos. The embryos can be stored for years, once they are frozen. However proper maintenance of cryocans in which the embryos are stored should be ensured, to make sure they are filled with liquid nitrogen regularly. Also, there is a storage fee which needs to be paid annually
How can some embryos have 3 cells ?
Ans: When we describe cell division, we say that one cell divides into two; two divide into four; and four divide into eight. However, do remember that these cells can divide at different times. Thus, if the first cell divides at 4 pm; and the next at 8 pm, and we check the embryos at 6 pm, then this embryo will have 3 cells.
Why don't all the normal embryos implant ?
Ans: Even though an embryo may look completely normal, this does not mean that it is genetically normal. Human reproduction is not very efficient, and over 60% of all embryos even in young fertile couples have been proven to be genetically abnormal.
Can you ensure the embryos is genetically normal ? Do we need to do genetic testing before embryo transfer?
Ans: Genetic testing or PGD is not useful as a routine prior to embryo transfer. It is done only if there is a risk of any genetic disease.
What happens to the embryos which do not implant ?
Ans: These embryos stop dividing after the embryo transfer because they are not viable. When the cells die, they are reabsorbed like all other dead cells. This is a microscopic process, and there is no pain or bleeding when this happens. The death of these embryos does not affect the other embryos, which will continue to implant normally.