Fertilization is the union between sperm and egg. When using artificial reproductive technologies this union is completed outside the womb and is called In Vitro Fertilization, or IVF.
The process involves hormonally controlling the ovulatory process, removing ova (eggs) from the woman’s ovaries and letting sperm fertilize them in a fluid medium. The fertilized egg (zygote) is then transferred to the patient’s uterus with the intent to establish a successful pregnancy.
Intracytoplasmic Sperm Injection
Intracytoplasmic sperm injection or ICSI is a laboratory procedure involving micromanipulation of both the egg and sperm. It is the process of injecting a single sperm into the female partners egg to achieve fertilization. ICSI has been approved for treatment of male infertility by the American Society since 1993.
ICSI was originally performed to bypass male infertility issues. These issues ranged from the presence of antisperm antibody, obstructive issue where sperm are not released in the ejaculate, or issues with sperm morphology (shape). Most recently, ICSI has been used in a more liberal manner, such with an idiopathic female diagnosis or low egg number at retrieval, to maximize fertilization potential and avoid fertilization failures.
The most recent indication for ICSI is for those patients requiring Preimplantation Genetic Diagnosis (PGD). At The Center, PGD is performed by biopsying a small portion (~ 4 cells) of the trophectoderm on day 5 or day 6 of culture. At this stage of culture, the embryo has already exhibited its first sign of differentiation. The Inner Cell Mass (ICM) which becomes fetal material and Trophectoderm Cells (TE) that will eventually make up the placentome. Patients requiring PGD undergo ICSI because during a conventional insemination, 1 to 100 sperm cells may have embedded in the zona (the gelatinous outer covering of the oocyte/embryo proper), possibly introducting exogenous or “extra” DNA, and contaminating the biopsied sample.
At The Center, fertilization rates average around 80%, but can vary due to age, diagnosis and sperm quality.
Preimplantation Genetic Diagnosis (PGD)
Preimplantation Diagnosis, or PGD, is an ART technique that allows the testing of the genetic makeup of an embryo prior to embryo transfer. When performed in conjunction with IVF, it allows physicians to determine the genetic competency of an embryo, in the hope of reducing pregnancy loss.
Specifically, PGD can determine several genetic defects in a particular embryo, including; single gene mutations (such as Cystic Fibrosis or Fragile X), abnormal chromosome numbers (anueploidy) and translocations. There are two types of translocations:
- Balanced Translocations have no missing or extra genetic information, just improperly arranged chromosomes
- Unbalanced Translocations involve extra or missing genetic material
Preimplantation Screening (PGS)
One of the most exciting recent developments in Premimplantation Genetic Diagnosis is the development of Quantitative Polymerase Chain Reaction (qPCR). At The Center, qPCR is combined with IVF to determine the genetic ploidy (correct chromosome #) of each individual embryo. This allows for the replacement of competent embryos at transfer.
The qPCR Process
Initially, each patient working closely with Dr. Robins, will determine the efficacy of performing qPCR. If it is determined that you will benefit from qPCR technology, the process will proceed as follows:
For all qPCR patients, ICSI must be the method of fertilization. This is to defer any exogenous DNA contaminating the biopsy sample, as many sperm may imbed the zona pellucida following conventional insemination. On day 3 of culture (when the embryo is an 8 cell), a small hole will be drilled into the zona of each embryo to allow for prolapsing of the trophectoderm cells on day 5 or 6 of culture as the blastocyst expands and increases in cell number.
Cell biopsies will be performed on day 5 or 6 of culture at the blastocyst stage. At this stage of development, the embryo has produced its first signs of differentiation. Notably, blastocysts will show an inner cell mass (ICM; fetal material) and a Trophectoderm (TE) (Placentome) cell structures and will contain 80 to 100 cells total. At biopsy, ~4-6 cells of TE will be lazered off for genetic testing.
qPCR Analysis and Embryo Transfer
Cells will be placed in a lysing solution here at The Center and shipped Reproductive Medical Associates of New Jersey (RMANJ) for qPCR testing. Biopsies may be evaluated right away by RMANJ or they may be banked until a consensual number of embryos/biopsies are obtained over a series of IVF cycles. Results will be sent to Dr. Robins for interpretation and you will be notified by your Nurse Coordinator as to the number of chromosomally normal embryos were developed. Abnormal embryos will not be transferred at The Center. On rare occasion, a result may come back “Unamplified”. In this case, no genetic material was available for testing, Dr. Robins will discuss this with you to determine the next steps.