••• Chapter 55^ Assisted Reproductive Technology^555
(6) Embryo development is carefully observed for the next 2 to 5 days. Using criteria such as the rate of cleavage,
cell symmetry, fragmentation rate, etc, the embryologist attempts to choose the embryos with the highest
probability of implantation.
(7) The selected embryos are transferred into the uterus under ultrasound guidance
(8) The remainder of the embryos may be frozen for the patient’s future use.❍ How do you prevent the patient from having a spontaneous LH surge?
One of two possible additional medications is typically giving in addition to gonadotropins
(1) A gonadotropin-releasing hormone (GnRH) agonist. The GnRH agonist is started in the midluteal phase
of the preceding cycle and will cause ovarian suppression by downregulation and desensitization of pituitary
gonadotropin receptors. Once the ovaries are suppressed, the gonadotropins are administered concomitantly
with the GnRH agonist until the day of hCG injection. The most widely used GnRH agonist is leuprolide
acetate. The GnRH agonist “turns off ” the pituitary.
(2) A GnRH antagonist. The antagonist competes with native GnRH molecules for pituitary binding sites, thus
causing an immediate suppressive action and requires a shorter administration period. The GnRH antagonist
“blocks” the pituitary from seeing GnRH.
❍ How is multifollicular recruitment monitored?
Recruitment is monitored with daily estradiol measurements and ultrasound.
❍ Why is hCG administered instead of LH to simulate the “LH surge”?
hCG is given at a dosage of 5,000 to 10,000 IU to aid in final maturation of the oocytes. hCG binds to the LH
receptors, having the same effect but with a longer half-life.
❍ What is ICSI? What is “conventional insemination”?
A single sperm is injected into a mature oocyte. Typically, this is done if the partner has a very low sperm count,
low motility, or poor morphology. With conventional insemination, a microdroplet of media is placed in a Petri
dish containing both the oocytes and a sample of washed sperm diluted to about 1 to 1.5 million/cc.
❍ How can you tell if the eggs fertilized?
Oocytes are examined approximately 17 hours after ICSI or insemination. A normal fertilized oocyte will contain
two polar bodies and two pronuclei, which will be visible under the light microscope. The presence of one polar
body indicates nonfertilization (no male pronucleus), while three polar bodies suggests polyspermy (two male
pronuclei).
❍ How many embryos are transferred back to the uterus?
In general, the younger the patient and the better the prognosis, the fewer the embryos that are transferred. This
is because the older the patient, lower the likelihood that the embryo will implant and develop into a normal
pregnancy.
The American Society of Reproductive Medicine guidelines recommend in general, for cleavage-stage embryos:
Under age 35—one to two.
Age 35 to 37—two to three.
Age 38 to 40—three to four.
Over age 40—five.