Rishina Bansal/Navin Desai
Introduction
As known Assisted reproductive technology (ART) comprises of intra-uterine insemination (IUI), conventional In-vitro fertilization (IVF) and intra-cytoplasmic sperm injection (ICSI). Though currently, when we talk about an IVF cycle, we are largely referring to conventional IVF or ICSI. The decision of applying which process would depend upon what information we have regarding the couple based on couple history, their current examination report like semen analysis and ovarian scan.
In general, every IVF lab should be governed by parameters known as key performance indicators (KPIs) or sometimes referred to as performance indicators (PIs) which are important for the systematic monitoring of the laboratory.
Basis:
As embryologists, we term the OPU day as Day 0 and we culture the embryos thus formed maximum to Day 5 sometimes to Day 6, thus a typical embryology cycle spread across Day0 – Day5/6. However, the preparation for the cycle starts a day prior, that being, Day -1. Thus, from an embryologist’s perspective, our cycle timelines spread across Day -1 to Day 5/6.
Day -1:
On Day -1, it is important we, we gather some basic information regarding the couple. Essentially the age, previous history of conception, any IVF cycles, semen parameters, amh levels or follicles expected, whether the cycle is just oocyte freezing and equally important whether the couple has been tested for viral markers and what is the corresponding report. Each parameter listed above helps us look into possible changes we should or should not make for better success and outcome. If there has been a previous conception, we know higher possibility of forming blastocysts so we can take the cycle up to Day 5 and suggest PGS.
Previous IVF cycles help us understand how the gametes behaved, whether embryos formed, how many embryos, their grades and what was their fate. Looking at the semen parameters gives us multiple suggestions on whether there is underlying male factor or not. Depending on the underlying male factor, we could change the way we process the sperm or apply advanced sperm function tests. Expected number of follicles are important to create enough working material on the day of OPU and then onwards.
Day 0:
All the above information helps us be prepared for the Day0 which is the day we retrieve oocytes and depending on the cycle perform either conventional IVF, ICSI or oocyte freezing. For instance, if it is just oocyte freezing, it not important to prepare for ICSI and further culturing as the cycle stops on Day0. Similarly, higher number of follicles will ensure we prepare more dishes to ensure limited exposure of the gametes.
We know that an IVF/ICSI cycle has 5 stages to be prepared for; 1 in andrology and 4 in embryology. For andrology it is relatively simple, and we need to remove a washing buffer and some culture media in proportion as per the laboratory’s SOP. Both the buffer and the culture media need to be equilibrated in the CO2 incubator with either tight lid or lose lid depending upon the type of media used.
As for embryology there are 4 stages we need to prepare for; namely, OPU, denudation, IVF/ICSI and culturing. When preparing for an OPU, you have to remember to prepare for two sub steps; one removing media and oil for the holding dish and two involves making a dish for incubating the retrieved oocytes. The holing dish will be used to screen oocytes from the follicular fluid and blood removed during OPU. The screened oocytes then are washed and kept in the incubating dish.
In a similar way, depending on the process performed, we have to make the remainder of the dishes. E.g if IVF, then we do not make a denudation or ICSI holding dish and culture dish. The culture dish for IVF is made on the OPU day to be used next day. However, IF we perform ICSI, then we need a denudation dish, media & oil for the injection dish and culture dish to transfer the injected oocytes. It is important to note, all dishes prepared for use have to be made a day prior to use. As per good practices, a minimum of 8 to 12 hours of incubation.
Fertilization, Day 2 to ET/FET:
Now the next important steps remain to check the fertilizations as per injection time on Day 1, separate the fertilized zygotes from the unfertilized oocytes and culture the fertilized zygotes for embryo growth. From here on, timely check of the embryos on Day 2 followed by Day 3 checks need to be performed.
If your laboratory uses sequential media, then you have to change the dish for culturing the embryos beyond Day3, which preparation is done a day prior, in this case on Day 2. Similarly if your laboratory does not culture the embryos to the blastocyst stage then, depending on whether the cycle is an all freeze cycle or fresh transfer cycle, you have to prepare an embryo transfer dish A daye before embryo transfer.
The only difference between a fresh and frozen cycle, is that in a frozen cycle (Thaw ICSI/ or Thaw conventional IVF) you will not have to dispense any media and oil for the holding dish which you will for a fresh cycle. A good practice would be to make a list of all OPU’s, Day 3 – Day 5 changes, embryos transfers and thaw procedures.
Thus as discussed here, planning is a critical step in the smooth running of an IVF lab, which, will help in delivering the desired results as also help you gather some information if anything goes wrong.
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