Embryo transfer: Practice makes perfect

May 2008
SFV


Clinicians should routinely carry out a
“dummy run” before performing embryo
transfer, according to a leading
in- vitro fertilization (IVF) expert.
“A lot of people don’t do it because it
takes time and is costly to do a trial transfer
… but it’s well worth it,” said Dr. Bill Yee,
clinical professor of obstetrics and gynecology
at the University of California, Los
Angeles, and the University of California,
Irvine, US.
The ease of embryo transfer is a known
predictor for pregnancy, and success rates
are significantly lower among patients who
experience a “difficult” transfer. [Hum Reprod
2002;17:2632-5]
“Difficult transfers occur in about 10
percent of patients,” said Yee. “If you can
convert those 10 percent into easy transfers
then it will improve your success rate.”
Dummy transfers can be used to assess
key features of a patient’s anatomy, such as
the uterine depth and the direction of the cavity.
This process also enables identification of
cervical stenosis, acute utero-cervical angles,
and endocervical ridges and blockages – factors
which can complicate the transfer process.
Obtaining prior knowledge of these factors
can help clinicians to formulate an appropriate
strategy for the actual transfer, said Yee.
Once a potentially difficult transfer is
identified, clinicians can select the catheter
that will be best suited to the procedure and
decide whether to use ultrasonography for
guidance. Cervical dilatation can also be
planned in order to facilitate the actual transfer
process. Identification of abnormalities
during a trial transfer can prompt further
investigation with hysteroscopy or sonohystography
and, in cases of severe blockage, reconstruction
of the endocervical canal might
be indicated.
In Yee’s practice two trial runs are performed
before undertaking embryo transfer.
The first is performed in advance; the second
immediately prior to the actual procedure.
“If you find it to be difficult then it gives
you time to do something to the endocervical
canal,” he explained, adding that less expensive
catheters can be used for the dummy
runs.
The benefits of performing dummy transfers
have been known for some time. Data
from a randomized controlled trial comprising
335 embryo transfers demonstrated that
the pregnancy rate was 22.8 percent among
those who had undergone a trial transfer,
compared to 13.1 percent among those who
had not. [Fertil Steril 1990;54:678-81]
Yet despite these findings, Yee believes
that this technique has not yet become routine
practice. “In the United States we found that
about 60 percent of clinicians will do a trial
transfer,” he said.
Yee also stressed the importance of embryo
transfer within the overall process of
IVF, and urged clinicians to give greater attention
to this stage.
“I think that many programs see this
as equivalent to artificial insemination and
therefore little training is actually applied to
this procedure. I still see places where whoever’s
free will do the transfer. You have worked
so hard to develop these embryos and blastocysts
and the final transfer is critical to IVF
success, yet this procedure is often left to the
least experienced clinician in the practice,”
Yee concluded.