The Egg Race – A Dozen [Ripe] Eggs Please

The Egg Race – A Dozen [Ripe] Eggs Please

Today is day 11 of stimulation and I had an ultrasound scan this morning.  There are seven follicles on the right ovary measuring between 15-22mm in diameter and four follicles on the right measuring between 19-26mm in diameter.  There is also one more on the right ovary which is measuring 13mm in diameter and could possibly have a growth-spurt and reach 15mm by egg collection.

That’s a dozen in total, so I’m singing [in my head] my own version of The Pointer Sisters: “I’m so eggcited, I just can’t hide it…”

The blood work came back showing that the estrogen levels are up too, so we’re ready to go:  double-trigger LH shots (Gonasi 5000 IU and Suprecur 1 mg) this evening – bam! – and collection scheduled for Wednesday, 8.30am.  In my previous three rounds, I triggered with a single shot of Ovitrelle 250 mcg but in this round our consultant wants to try a double LH trigger in the hope that more eggs mature.   Lucky egg collection is not on Friday because: “what’s the eggs worst day?”…..  “fry-day”. (I just realised that I had egg collection on a Friday in The Disaster Round. That explains a lot.)

There’s all this talk about “mature”, “immature” and “post-mature” eggs.  For a sperm to be able fertilise an egg, the egg needs to be mature.  If the egg is immature, the embryologist can’t perform ICSI or IMSI on it (i.e. inject the sperm).  A post-mature egg won’t create a viable embryo or a healthy baby, so you want them to be mature – just ripe, like an avocado.  This is a great article on Dr Sher’s blog, explaining the importance of egg maturity in IVF.

I like knowing what’s going on, so I’ve had to brush up on my A-level biology. Eggs develop in follicles, which are fluid filled structures in the ovaries.  Each follicle contains one teeny egg, loosely attached to the wall of the follicle.

For an egg to mature, it needs to go through meiosis, which is the reproductive division process where first, the chromosomes are copied (DNA replication) and then the cell divides twice, resulting in four cells with different fates (this article explains meoisis well).  One of those cells develops into an egg (ovum) and the other three into polar bodies, which disintegrate.  The egg gets all the resources (cytoplasm, mitochondria) and may get fertilized.

This process begins 36-42 hours prior to ovulation.  The pituitary gland produces luteinizing hormone (LH), which is secreted at very low levels throughout the menstrual cycle.  Once a developing egg follicle reaches a certain size LH secretion surges to really high levels. This LH hormone surge is what triggers ovulation about 24 to 36 hours later.  In IVF, the ovulation process is mimicked by taking the LH trigger 36 hours before egg retrieval (ovulation).

The cells that are formed by meiosis have half as many chromosomes as the cell that formed them. Human body cells contain 23 pairs of chromosomes (haploids), while human gametes (mature eggs and sperms) contain 23 single chromosomes (diploids).  When the mature egg with 23 single chromosomes is fertilized by the sperm, an embryo forms with 46 chromosomes, 23 pairs (a so-called euploid).  This GCSE BBC science article has a great diagram explaining the cell division process.

Embryos with more or less than 46 chromosomes (euploid) are “incompetent” and generally either arrest during development, fail to implant normally, are lost in early miscarriage, or will result in a chromosomal developmental defect (e.g. Down syndrome).

You can’t tell for sure whether an egg is mature prior to egg collection – the nurse / doctor estimates based on size of the eggs (usually 15-20mm indicates that an egg is mature) and hormone levels in your blood.  After egg collection, the embryologist can confirm, through examining the egg in a microscope, whether the egg is mature or not but it can’t see whether it is a euploid or anaeuploid.

I don’t know why I miscarried (read my letter to my angel baby here), but there is a high probability that the embryo wasn’t a euploid and naturally aborted. I know that at my age (38), statistically, only 30% of my eggs are capable of forming competent embryos. This is why H and I have decided to have our embryos screened for chromosomal abnormalities this time (PGS) – provided our embryos get to the full blastocyst stage.  Statistically, the more eggs we have the better chances we have of creating competent embryos.

Double trigger tonight at 8.30pm, egg collection scheduled for Wednesday at 8.30am.  May I please have a dozen ripe eggs for breakfast on Wednesday?



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