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It is not possible to predict with certainty which oocytes (eggs) will fertilize and form preembryos (fertilized eggs) or blastocysts (an advanced stage of development of the preembryo-usually on day 5-6). Therefore, when normal appearing oocytes are fertilized, often more preembryos/blastocysts will form than should safely be placed into the uterus or in the fallopian tube. In anticipation of "extra" preembryos/blastocysts, couples must decide what to do with them.

Preembryos/blastocysts are "graded" prior to selection for transfer to the uterus or tubes.

Grading preembryos is an evaluation of the preembryos, which is initially performed in the ART laboratory on the second day after the egg aspiration and sperm collection. Blastocysts are graded usually on day 5 or 6. The laboratory staff evaluates the embryos under the microscope for morphological (structural) characteristics of quality, which are visible under the microscope. This evaluation is based on standardized laboratory assessment criteria that include cell shape and size. The preembryos/blastocysts are not being evaluated for genetic characteristics.

The preembryos/blastocysts selected for transfer during the initial or "fresh" cycle are the highest in quality, or grade, since this is the cycle with the optimal chance for pregnancy. There are several options available for preembryos/blastocysts in excess of those transferred to the uterus or tubes.

1. Cryopreservation (freezing) of preembryos

2. Disposal of preembryos/blastocysts according to the ART Program's practices and procedures at that time.

3. Use of the preembryos/blastocysts for scientific education or research.

4. Donation of the preembryos/blastocysts to another infertile couple, if a couple is available. (This option requires an additional consent form and advanced planning for coordination with another couple. It assumes that the donating couple is available for testing at the time of donation, i.e., HIV testing. It also assumes that the preembryos/blastocysts are desirable in terms of egg and sperm quality, i.e., age less than 35).

Making the decision to cryopreserve preembryos/blastocysts is frequently confusing for couples and this explanation is an attempt to clarify some of the issues. Couples must make their choices in writing, in advance of the ART cycle, when they sign their consent forms with their physicians. It is probably better for couples to assume that they will have additional preembryos/blastocysts, and if so, what would they want to do with them. Cryopreservation may be performed as early as one day before the embryo transfer, therefore making changes to the original consent form is very difficult. Patients should be cautious not to second-guess their original thoughtful decisions during the stressful time of the ART procedures. A revised decision must be communicated appropriately in writing to your physician, the facility, and the ART lab in order to be carried through properly.

Preembryos/blastocysts can be cryopreserved and transferred in a subsequent cycle should pregnancy not occur in the initial cycle. They may also be used to establish a sibling pregnancy at a later time if pregnancy occurs initially. Once cryopreserved, the viability of the preembryos/blastocysts is generally not thought to decline even after years of storage. However, we encourage couples to use them for transfer or decide on disposal within a reasonable time. One year is the original storage agreement.

Cryopreserved preembryos/blastocysts can be thawed and transferred to the patient during an unstimulated cycle at a considerably lower expense than a "fresh" cycle. Replacement of cryopreserved preembryos/blastocysts is performed at a time chosen by the doctor and ART laboratory as the most advantageous to the preembryos/blastocysts survival. Consent to the transfer must be reaffirmed at that time.

Some or all of the preembryos/blastocysts may not survive cryopreservation and thawing. Nationally, About 60% survive. The number of human births from cryopreserved preembryos/blastocysts to this date has been small and most of these births have been normal.

There does not appear to be an increased risk to the fetus by embryo cryopreservation and thawing, but it cannot be quantified with certainty until more live births result from cryopreserved preembryos/blastocysts.

Our current recommendation is to only cryopreserve preembryos/blastocysts that are "Grade I" or higher quality "Grade II". We believe the lesser grade preembryos/blastocysts are less likely to survive the thaw, or, if they survive the thaw, less likely to result in pregnancies.

These are some of the factors to consider when deciding whether or not to cryopreserve preembryos/blastocysts:

A. There are expenses involved in cryopreserving and storing preembryos/blastocysts.

B. The costs of a cryopreserved replacement cycle are less than a "fresh" cycle.

C. The pregnancy rates of a cryopreserved preembryos/blastocysts replacement cycle are lower than a "fresh" cycle.

D. Not all preembryos/blastocysts survive the cryopreservation and thaw process (possibly non may survive).

E. The preembryos/blastocysts remaining from a "fresh" cycle may not be "Grade I" or high-quality "Grade II".

Faced with decisions about whether to cryopreserve preembryos/blastocysts when there are only a few available for cryopreservation, couples frequently ask us, "Is it economically and statistically 'worth it' to freeze only one or two preembryos/blastocysts?", knowing that perhaps only one (or none) will survive the thaw?

An option is to cryopreserve only if there are three or more "Grade I" or high-quality "Grade II" preembryos/blastocysts available. This may increase the number of preembryos/blastocysts surviving the future thaw. If there are not three to four or more "Grade I" preembryos/blastocysts available to cryopreserve, then the consent form allows for default to the other options (numbers 2 and 3 listed earlier) selected by the couple.

Some couples can afford several "fresh" cycles, and they choose to cryopreserve any excess "Grade I" or high-quality "Grade II" preembryos/blastocysts in each cycle with the expectation there will eventually be enough cryopreserved preembryos/blastocysts "banked" to have several survive the thaw.

Of course we encourage each couple to make the best choice for themselves. If a couple has strong religious or moral beliefs that lead them to cryopreserve all preembryos/blastocysts, regardless of their grades, or which prevent them from choosing the other 3 options described above; that couples may direct us to cryopreserve all preembryos/blastocysts regardless of their grades.

Couples who store cryopreserved preembryos/blastocysts have an obligation to notify their physician and the ART program in writing of any change in their address. Additionally, there is a fee associated with the cryopreservation and storage of preembryos/blastocysts. If a couple pays for cryopreservation but then does not have enough preembryos/blastocysts available for cryopreservation to be performed, the couple will receive a refund in the amount paid for cryopreservation. Unforeseen increases in the cost of cryopreservation may dictate an increase in couples storage costs.

We hope this explanation serves to help you make decisions about whether to cryopreserve preembryos. Please feel free to contact us if you have further questions or concerns.