At Reproductive Medicine Institute (RMI), we strive to offer our referring community and our shared patients the most current information on Assisted Reproductive Technologies (ART). In this letter, we discuss what happens in the laboratory between retrieval and transfer during In Vitro Fertilization (IVF).
What Happens After A Retrieval? – Laboratory Perspective
Carli W. Chapman, BS, TS, ELD
The laboratory scientists at RMI have well over 100 years of combined experience in Assisted Reproductive Technologies (ART). All members of your laboratory team are credentialled to perform tasks and undergo regular competency evaluations. The laboratory scientists participate in ongoing educational activities to remain at the cutting edge of technology. At RMI, your laboratory scientists recognize the importance and critical nature of our job. We treat every gamete (sperm and eggs) and embryos with the respect our special positions afford to us.
The biggest fear most patients have about the laboratory is the mix-up of sperm, eggs or embryos. The laboratory at RMI has been using an independent electronic witnessing system called RI Witness that provides an electronic system of matching eggs, sperm and embryos to eliminate any human error. Also, RMI is the ONLY laboratory in the Chicagoland area that has actively been using an independent electronic witnessing system to ensure your gametes are correct every time.
The day before your retrieval, is the day laboratory begins you IVF process. The plan for your cycle created by you and your physician is reviewed with all laboratory scientists. The laboratory staff carefully review your stimulation results to estimate the number of eggs we expect to retrieve. Culture dishes are prepared for your retrieval for holding the eggs until fertilization takes place and growing your embryos after fertilization. Dishes are placed into the incubator assigned to you and the home to your gametes for the next week.
On the day of your retrieval, an embryologist will introduce themselves to you during your “time out” procedure. This is a process in which your identity is verified, and your procedure is confirmed. While you may only see one laboratory scientist at this time, please be assured there is an entire staff working for you in the background. In laboratory time, the day of your retrieval is day 0.
About 4 to 6 hours after your retrieval, your eggs are exposed to sperm. This exposure may be Conventional Insemination (CI) or Intracytoplasmic sperm injection (ICSI) depending on your personalized plan. CI is a process where thousands of sperm are placed next to your egg(s) and one sperm finds and fertilizes your egg. ICSI is a process in which one sperm is picked up using specialized tools and equipment and placed into the egg for fertilization. After sperm exposure your eggs are put into their incubator until fertilization checks. At RMI all scientists are credentialled to perform insemination procedures and the results are reviewed monthly to ensure that quality is maintained.
Fertilization checks occur 17 to 19 hours after exposure to sperm. This is considered day 1. Fertilized eggs are referred to as zygotes. A normal zygote has two-pronuclei; one supplied by the egg (mom) and one supplied by the sperm (dad). This genetic material will combine to form the full genetic complement of the embryo. Normally fertilized zygotes are separated from zygotes that did not fertilize or that fertilized in an abnormal way. Only normally fertilized embryos remain in culture. After fertilization checks you can expect a call from your IVF coordinator with fertilization results. During this call a wellness check also occurs to make sure you are not suffering unnecessarily from your retrieval procedure.
After fertilization check, your normal zygotes are put back into their assigned incubator space and cultured in a careful balance of carbon dioxide, oxygen and nutrients to promote embryo development. Your embryos will develop through specific stages, first cleavage stage (Days 1 – 3), followed by morula stage (Day 4) and finally to the blastocyst stage (Day 5 -6). Not all embryos will develop to the blastocyst stage. The blastocyst stage embryo is routinely transferred, biopsy and frozen at RMI. This is nearly a week after your retrieval!
Embryos are cultured undisturbed until your transfer and/or biopsy or freezing. It is the philosophy of the laboratory to only handle embryos if an actionable event is taking place – freezing, transfer, biopsy, etc. RMI was an early adapter of this philosophy because our laboratory scientists are well informed and leaders in our field. Most other Chicagoland programs are now adopting this philosophy. We know it is hard to wait for information, but it is better for embryo development.
RMI will do embryo transfers on Days 2 – 5 depending on the plan created by your physician. All embryos are given a grade prior to transfer. At RMI we use the Society for Assisted Reproductive Technology grading system which applies an overall grade of good, fair, and poor to each embryo. Good and fair embryos are selected for transfer, biopsy or freezing. Prior to your transfer, an embryologist will speak with you about the number and status of embryos you have in culture. Since we routinely culture embryos after your transfer, you will receive a call from the laboratory on culture Day 6 (remember your retrieval day is Day 0) after your retrieval, to confirm the number of embryos that were frozen and answer any additional laboratory related questions you may have.
At RMI we use a process for freezing call vitrification – or rapid freezing. Any extra good and fair embryos after your transfer or all good and fair embryos if no transfer is in your immediate treatment plan will be vitrified. We freeze embryos routinely on day 5 and day 6. Vitrification technology requires highly trained scientist but results in a survival rates of greater the 95%. The pregnancy rates from frozen embryos is equal to or greater than the rate from fresh embryos. Do not be afraid of a frozen embryo transfer.
Your laboratory team hopes this brief description helps you understand what happens in the laboratory. We are always available to you via email: firstname.lastname@example.org.