Zygote Intrafallopian Transfer: ZIFT
What is zygote intrafallopian transfer (ZIFT)?
ZIFT is an assisted reproductive procedure similar to in vitro fertilization and embryo transfer, the difference being that the fertilized embryo is transferred into the fallopian tube instead of the uterus. Because the fertilized egg is transferred directly into the tubes, the procedure is also referred to as tubal embryo transfer (TET). This procedure can be more successful than gamete intrafallopian transfer (GIFT) because your physician has a greater chance of insuring that the egg is fertilized. The woman must have healthy tubes for ZIFT to work.
The main difference between ZIFT and GIFT is that ZIFT transfers a fertilized egg directly into the fallopian tubes while GIFT utilizes a mixture of sperm and eggs.
How is ZIFT performed?
ZIFT is an assisted reproductive procedure that involves the following steps:
A woman’s ovaries are stimulated with medications to increase the probability of producing multiple eggs. Eggs are then collected through an aspiration procedure. Those eggs are fertilized in a laboratory in a procedure identical to IVF, with the exception of the time frame. During the ZIFT procedure, fertilized eggs are transferred within 24 hours, versus 3-5 days as used in a regular IVF cycle. The fertilized eggs are then transferred through a laparoscopic procedure where a catheter is placed deep in the fallopian tube and the fertilized eggs injected. The final step is to watch for early pregnancy symptoms. The fertility specialist will probably use a blood test to determine if pregnancy has occurred. Who should be treated with ZIFT?
ZIFT is an assisted reproductive procedure which may be the selected form of treatment for any infertility problems except the following:
Tubal blockage Significant tubal damage An anatomic problem with the uterus, such as severe intrauterine adhesions Sperm that are not able to penetrate an egg ZIFT is commonly chosen by couples who have failed to conceive after at least one year of trying and who have failed five to six cycles of ovarian stimulation with intrauterine insemination (IUI).
What are the similarities and differences between ZIFT and in vitro fertilization (IVF)?
ZIFT and IVF both tend to be favorable treatments for women who have more severe infertility issues such as damaged fallopian tubes. ZIFT and IVF both involve embryo culture. ZIFT and IVF both provide the physician with the opportunity to select only the best quality embryos for transfer. ZIFT transfers the fertilized embryo into the fallopian tube whereas the IVF and embryo transfer procedures result in the fertilized embryo being placed into the uterus. The ZIFT procedure differs from IVF in that the transfer of embryos into the tube requires an extra surgical procedure called laparoscopy.
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Preimplantation Genetic Diagnosis: PGD
Preimplantation genetic diagnosis (PGD), also called Preimplantation Genetic Testing (PGT), is a procedure used prior to implantation to help identify genetic defects within embryos created through in vitro fertilization to prevent certain diseases or disorders from being passed on to the child. In most cases, the female, male, or both partners have been genetically screened and identified to be carriers of potential problems.
How is the PGD performed?
The preimplantation genetic diagnosis begins with the normal process of in vitro fertilization that includes: ovary stimulation through medication, egg retrieval, and fertilization in a laboratory. Over the next three days the embryo will divide into 8 cells. The preimplantation genetic diagnosis involves the following steps:
1. First, a one or two cells are removed from the embryo. 2. Next, DNA is retrieved from the cell and copied through a process known as polymerase chain reaction (PCR). 3. Finally, by molecular analysis, the DNA sequence code is evaluated to determine if the inheritance of a problematic gene is present. Once the PGD procedure has been performed and embryos free of genetic problems have been identified, implantation will be attempted through embryo transfer, intracytoplasmic sperm injection (ICSI), or zygote intrafallopian transfer (ZIFT).
Who can benefit from PGD?
Preimplantation genetic diagnosis can benefit any couple at risk for passing on a genetic disease or condition. The following is a list of the type of individuals who are possible candidates for PGD:
Women ages 35 and over Carriers of sex-linked genetic disorders Carriers of single gene defects Those with chromosomal disorders Women experiencing recurring pregnancy loss associated with chromosomal concerns PGD has also been used for the purpose of gender selection. However, discarding embryos based only on gender considerations is an ethical concern for many people.
What does PGD look for?
Preimplantation genetic diagnosis looks for genetic and chromosomal problems that place the couple at risk for birth defects or spontaneous misscarriage. Research shows that PGD identifies the presence of the following disorders and the list continues to grow as technology improves:
Recessive sex-linked disorders such as hemophilia, fragile X syndrome, and most neuromuscular
Dominant sex-linked disorders
such as Rett syndrome, incontinentia pigmenti, pseudohypererp arathydroidism, and vitamin D-resistant rickets Single gene disorders such as cystic fibrosis, Tay-sachs, Huntington disease, and sickle cell anemia
Chromosomal rearrangements such as translocation, inversion, deletions and Aneuploidy What are the benefits of PGD?
The following are considered benefits or advantages of PGD:
The procedure is performed before implantation thus reducing the need for amniocentesis later in pregnancy. The procedure is performed before implantation thus allowing the couple to decide if they wish to continue with the pregnancy. The procedure enables couples to pursue biological children who might not have done so otherwise. The procedure may help reduce the costs normally associated with birth defects. What are the concerns of PGD?
The following are considered concerns or disadvantages associated with the use of PGD:
Many people believe that because life begins at conception and that the destruction of an embryo is the destruction of a person. In practice, the PGD procedure usually results in a small number of discarded embryos. In some cases, a genetically defective fertilized egg will mature without the presence of disorder or disease. The probability of disorder development should be a topic of discussion with the healthcare provider. While PGD helps reduce the chance of conceiving a child with a genetic factor, it can not completely eliminate this risk. In some cases, further testing done during pregnancy is needed to ascertain if a genetic factor is still possible. Although genetically present, some resulting diseases only generate symptoms when carriers reach middle age.
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Intracytoplasmic Sperm Injection:
Intracytoplasmic sperm injection (ICSI) involves the direct injection of sperm
into eggs obtained from in vitro fertilization (IVF).
How is ICSI performed?
There are basically five simple steps to ICSI which include the following:
1. The mature egg is held with a specialized pipette.
2. A very delicate, sharp, and hollow needle is used to immobilize and
pick up a single sperm.
3. The needle is then carefully inserted through the shell of the egg and
into the cytoplasm of the egg.
4. The sperm is injected into the cytoplasm, and the needle is carefully
5. The eggs are checked the following day for evidence of normal
Once the steps of ICSI are complete and fertilization is successful, the
embrto transfer procedure is used to physically place the embryo in the
woman’s uterus. Then it is a matter of watching for early pregnancy
symptoms. The fertility specialist may use a blood test or ultrasound to
determine if implantation and pregnancy has occurred.
Are there specific situations where ICSI might be recommended?
ICSI may be recommended when there is a reason to suspect that achieving
fertilization may be difficult. ICSI is most often used with couples who are
dealing with male infertility factors. Male infertility factors can include any of
the following: low sperm counts, poor motility or movement of the sperm,
poor sperm quality, sperm that lack the ability to penetrate
an egg or azoospermia.
Azoospermia is a condition where there is no sperm in the male’s
ejaculation. There are two types of azoospermia: obstructive and non-
obstructive. Obstructive azoospermia may be caused by any of the following:
Congenital absence of vas
Scarring from prior infections
Non-obstructive azoospermia occurs when a defective testicle is not
How is sperm retrieved for use in ICSI?
For men who have low sperm count or sperm with low mobility, the sperm
may be collected through normal ejaculation. If the man has had a
vasectomy, the microsurgical vasectomy reversal is the most cost-effective
option for restoring fertility.
Needle aspiration or microsurgical sperm retrieval are good alternatives
when a competent microsurgical vasectomy reversal has failed, or when the
man refuses surgery. Needle aspiration allows physicians to easily and
quickly obtain adequate numbers of sperm for the ICSI procedure. A tiny
needle is used to extract sperm directly from the testis.
Needle aspiration is a simple procedure performed under sedation with
minimal discomfort; however, there is the potential for pain and swelling
afterwards. The sperm obtained from testis is only appropriate for ICSI
procedures when testicular sperm is not able to penetrate an egg by itself.
What health concerns are there when considering ICSI?
There have been studies indicating that developing babies from pregnancies
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achieved through artificial insemination, and particularly ICSI, may face an
increased risk for some birth defects, such as imprinting defects. Imprinting
refers to the phenomenon in which certain genes function differently
depending on whether they involve a particular chromosome passed on by
the father or by the mother. Reproductive researchers are concerned that
manipulation of either gametes or zygotes may affect the imprinting process
or the subsequent release. Other researchers believe that the incidence of
these birth defects occurring is similar to those achieving pregnancy without
ART procedures and therefore should not be a deterrent in using them. The
potential risks or complications from doing ICSI is something that you should
discuss with your reproductive specialist at length about.