|
| |
Factors
Influencing IVF Success Rates
During the past few years, evidence has accumulated
that the presence of a unilateral or bilateral hydrosalpinx ( obstructed
and dilated tubes ) reduces the success rate after IVF and embryo transfer.
The mechanism for this is not clearly understood although there is evidence
for embryotoxicity in the tubal fluid and lack of expression of markers
of implantation in these patients. There also is evidence that removal
( usually by a laparoscopy on an outpatient basis ) of the affected tube/s
improves significantly the pregnancy rate. If you think that you have
such affected tubes, please discuss this with your doctor.
Endometriosis is
one of the reasons leading to infertility.
Endometriosis can result in pelvic inflammation, scarring, and tubal
obstruction. However, our IVF success
rates in women with any stage of the disease are reassuring, both
in terms of fertilization and pregnancy rates. In our program, patients
with endometriosis, tubal disease, or unexplained infertility, have similar
success rates.
Embryo cryopreservation
has revolutionized IVF and positively influenced success rates. The
number of embryos transferred in a "fresh cycle" is limited
to reduce the incidence of multiple pregnancies; therefore, patients can
use their frozen embryos for future pregnancy attempts. This provides
added chances of achieving a pregnancy without having to undergo an additional
stimulated IVF cycle, which offers cost and time advantages. At the Jones
Institute, embryo cryopreservation has been available since 1986; our
success rates are among the highest in the world.
Patients are strongly cautioned regarding making comparisons
of success rates between IVF clinics based on the clinic - specific data
reports released by the Society for Assisted Reproductive Technology (
SART ) and the Centers for Disease Control ( CDC ). Although SART issues
a statement that these data should not be used for comparison, the fact
is that they are used by patients and clinics alike for that purpose.
There are many variables that influence IVF success rates and many variables
exist among individual clinics that make comparisons almost impossible
based on the released data. Some of these problems of the clinic - specific
data reports include:
- The SART data are not divided into repeat and new
IVF patients. For example: patients under the age of 35 in a particular
clinic may have repeated failed IVF attempts before and would have a
poor prognosis even though they have a favorable age.
- The population mix of individual clinics is totally
unaccounted for in the SART - released data. For example, a clinic that
pushes IVF treatment ( which may be justifiable in many circumstances
) as the primary modality of therapy for patients with non - tubal infertility,
may have higher success rates than a clinic that offers IVF to its patients
only after many failed conventional treatments ( IUI's, for example
). The different population of patients being treated may largely account
for the higher success rate, in this example.
- The criteria for patient acceptance and for cancellation
prior to egg retrieval vary among clinics and, as such, influence pregnancy
rates tremendously. For example, a clinic that does not accept patients
beyond a certain age ( i.e., 40 ) and patients with poor ovarian response
( high basal FSH levels and abnormal clomiphene citrate challenge test
) will have higher success rates than a clinic that does not exclude
these patients. Again, the higher success rates will be largely attributed
to the patient population.
- . The policy for fresh embryo transfer and embryo cryopreservation
is very different among clinics and greatly influences the pregnancy
rates. For example, clinics that culture all the embryos and transfer
only the morphologically best embryos may have better fresh pregnancy
rates than clinics that culture only the desired number of embryos for
transfer, and freeze all the rest at the pronuclear stage. There are
many advantages in freezing excess embryos that include giving patients
another chance for embryo transfer without repeating stimulation and
egg retrieval, and reducing the incidence of multiple fetuses.
These are only some of the examples that can be listed
that clearly invalidate comparisons between IVF clinics based on the released
SART clinic - specific data reports.
|
Phone
800-515-6637 or 757-446-7100