The field of ART (Advanced Reproductive Technology) is filled with confusing acronyms. Here's an overview in a nutshell.
| |
Eggs
Retrieved? |
Fertilized Where? |
Fertilized How? |
Embryos
Incubated? |
Embryos
Implanted? |
PGD
Possible? |
| IUI |
No |
Mother |
Naturally |
(No embryos) |
(No embryos) |
No |
| GIFT |
Yes |
Mother |
Naturally |
(No embryos) |
(No embryos) |
No |
| IVF |
Yes |
Lab |
Egg and sperm
mixed together |
3-5 days |
Uterus |
Yes |
| ICSI |
Yes |
Lab |
Single sperm
injected into egg |
3-5 days |
Uterus |
Yes |
| ZIFT |
Yes |
Lab |
Same as IVF |
1 day |
Fallopian Tube |
No |
| TET |
Yes |
Lab |
Same as IVF |
2 days |
Fallopian Tube |
No |
Is egg retrieval required?
All procedures, except IUI, include egg retrieval. Egg retrieval means that the mother takes fertility drugs to induce her ovaries to produce many eggs (called ovarian hyper-stimulation). Under anesthesea, the eggs are removed from the ovaries using a long needle inserted through the wall of the vagina. After retrieval, the eggs may be evaluated and possibly fertilized in the lab.
Where does fertilization take place?
In two procedures, IUI and GIFT, ferilization occurs in the mother's body. Egg and sperm meet in the fallopian tube, just as they would after intercourse.
In IUI, sperm are simply squirted into the mother's uterus. The sperm cells must find their way into the fallopian tube, hoping to find and fertilize the egg. The IUI is carefully timed to coincide with ovulation, which happens naturally, or is induced by fertility drugs.
In GIFT, eggs are retrieved from the mother, and sperm is obtained from the father. The two are placed together in the mother's fallopian tube using laparoscopic surgery, where fertilization is allowed to occur naturally.
In all other procedures, fertilization happens in the lab.
How does fertilization take place?
When fertilization happens in the lab, one of two methods is used.
Regular IVF fertilization -- A drop of sperm is placed with the egg. A sperm cell penetrates and fertilized the egg on its own.
ICSI -- A single sperm is selected, and injected right into the egg.
An ICSI cycle is exactly the same as IVF, except for this part about how the sperm gets into the egg. Yet, rather than just calling use this this technique an "IVF cycle with sperm injection" the entire cycle is now referred to as an "ICSI cycle" rather than an "IVF cycle".
How long are embryos incubated?
In IVF or ICSI, embryos are incubated 3 to 5 days. A 5-day embryo is called a blastocyst, so when these embryos are replaced in the mother, it's called a "blastocyst transfer" rather than an "embryo transfer".
ZIFT and TET are exactly the same procedure -- placing embryos into the mother's fallopian tube -- except for the length of embryo incubation.
Where are embryos implanted (or transferred to)?
In IVF or ICSI, embryos are placed in the mother's uterus. In ZIFT or TET, embryos are placed in the mother's fallopian tube.
Is PGD possible?
In order to take advantage of PGD, IVF or ICSI must be used, because PGD is performed on a 3-day old embryo,