Preimplantation Genetic Diagnosis (PGD)

PGD involves taking a single cell, or blastomere, from a developing embryo and testing it for genetic disease or chromosomal abnormality. As a result, for an increasing number of genetic conditions, PGD allows only those embryos diagnosed as being free from the genetic condition to be transferred back to the uterus for implantation and possible pregnancy.

Who Benefits from PGD?

Both fertile and infertile patients can benefit from PGD technology. PGD is an excellent resource for those patients who:

• Are at risk of transmitting genetic diseases to their children. PGD was developed to test the embryo for genetic conditions in which the specific gene involved was known. Single gene disorders, such as Tay Sachs, Huntington’s disease, Cystic Fibrosis, and Muscular Dystrophy are some examples; they are passed down in families from the mother or the father.
  
  
• Are older than 35 years of age. The sperm and the egg each contribute 23 chromosomes to the resultant embryo for a total of 46 chromosomes (23 pairs), including the sex chromosomes. If there is an extra chromosome present or a chromosome is absent, termed aneuploidy, that embryo is considered genetically abnormal. With advanced maternal age (>35 years old) there is an increased risk of a pregnancy having aneuploidy. The most talked about aneuploidy in women with advanced maternal age is Down’s syndrome. This occurs when there are 3 copies of chromosome 21.
  
  
• Have had repeated miscarriages. Using PGD we are able to test for 7 chromosomes, #13, 16, 18, 21, 22, and the sex chromosomes X and Y. An extra copy of certain chromosomes (#13,16,18,22) can result in miscarriage or birth of a baby with very serious birth defects that are usually incompatible with life.
  
  
• Have been found to be "balanced translocation" carriers. This person has a complete set of 23 pairs of chromosomes (46 in total) and appears healthy, however, 2 of the chromosomes have exchanged pieces. This does not cause any apparent problem in the individual until that time they start trying to conceive. It is possible for the resultant embryo of this person to be an "unbalanced translocation" carrier. Miscarriage is very common in this scenario, however birth of a baby with varying degrees of birth defects is possible.

When is PGD performed?

PGD must be done in conjunction with an IVF cycle. After fertilization in the laboratory, the resultant embryo is allowed to grow up to day 3. Specially trained embryologists then perform the biopsy and the cell is analyzed either by Fluorescent In Situ Hybridization (FISH) or Polymerase Chain Reaction (PCR). The embryos diagnosed as normal will then be transferred back to the uterus and/or cryopreserved on day 5 at the blastocyst stage of development.

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Intracytoplasmic Sperm Injection (ICSI)

Intracyctoplasmic sperm injection (ICSI) is a laboratory procedure whereby, using micromanipulation, a single sperm is injected directly into the cytoplasm of a mature egg. This process increases the likelihood of fertilization when there are abnormalities in the number, quality, or function of the sperm or when there are problems with sperm penetration of the egg. ICSI must be done in conjunction with an in-vitro fertilization cycle.

Who benefits from ICSI?

• Couples diagnosed as infertile due to male factor infertility. There are several conditions that can cause male factor infertility. Sperm can be completely absent in the ejaculate, a condition known as azoospermia or men can present with very low concentrations of sperm in the ejaculate, a condition known as oligospermia. Asthenospermia, which is poor sperm motility, occurs when the sperm do not have the forward swimming motion needed to unite with the egg in the female oviduct. Men with male infertility may also have a condition known as teratospermia, which is an increased percentage in abnormally shaped sperm. There may also be problems with the function of the sperm, decreasing their ability to bind and/or to fertilize the egg.
  
  
• Patients who have had failed natural fertilization during a previous IVF cycle. This may occur even though the male partner appears to have normal sperm counts, motility, and morphology.
  
  
• Patients using frozen sperm that may be limited in number and/or quality.
  
  
• Diagnosis of antisperm antibodies bound to spermatozoa or female antisperm antibodies that are thought to be the cause of infertility.
  
  
• Patients who have a low number of eggs and want to maximize their chances of fertilization.

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Assisted Zona Hatching (AZH)

Assisted Zona Hatching (AZH) is a procedure that, in select patients, may help to increase the chances of embryo implantation and pregnancy. The Preimplantation embryo is surrounded by a protective "shell" called the zona pellucida. This shell is necessary for embryo development up to the blastocyst stage (about day 5). Once the blastocyst has been formed, the embryo must break free (hatch) from the zona pellucida in order for implantation and pregnancy to occur.

AZH is a micromanipulation technique performed when the embryo is at Day 3 of development. The embryos are usually between the 6 to 8 cell stage. During the AZH procedure, a hole is created in the zona of the embryo using a small amount of acid. This is done a few hours before the embryo transfer. This gap in the embryo’s zona facilitates the embryos ability to hatch free of the zona pellucida when it expands as a blastocyst in the uterus. One potential explanation for failure of implantation is that the embryo is unable to escape from the zona pellucida.

Who benefits from AZH?

Assisted hatching is most useful for the following types of patients:

• Patients who are older than 38 years of age.
  
  
• Patients with elevated levels of follicle stimulating hormone (FSH).
  
  
• Patients whose embryos have a thicker than normal zona pellucida, as measured by trained embryologists.
  
  
• Patients who have had multiple previous IVF attempts with failed implantation.

What are the benefits of AZH?

Assisted hatching may increase the probability of embryo implantation, thereby increasing the chance of achieving pregnancy through IVF.

What are the risks of AZH?

There is a small risk of damaging the embryos during the assisted hatching procedure. All embryologists performing AZH at Dr. Karande & Associates, S.C. are fully trained in the practice of AZH making the risk minimal.

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