Abstract
BackgroundSingle blastocyst transfer has the advantage of maximizing the fresh single pregnancy rate. However, in patients with a low number of good quality embryos on day 3, it remains unclear whether immediate embryo transfer or further embryo culture with blastocyst transfer is the most preferable option.MethodsA retrospective cohort study was carried out in which the outcome of 590 fresh in vitro fertilization (IVF) cycles over a 15 months period and their cryo cycles were analyzed. A total of 341 patients cycles had an elective day 5 strategy independent of intermediate embryo evaluation while another 249 patients underwent a day 5 embryo transfer only if at least four embryos were available on day 3. Blastocyst vitrification was performed using a closed high security system.ResultsDemographics, stimulation parameters and embryological data were comparable in the two groups. Patients in the elective day 5 group had a lower fresh transfer rate (90.62% vs. 95.18%, p < 0.05) as compared to patients with a day 3 or day 5 embryo transfer policy. No difference was observed in the fresh live birth rate and multiple pregnancy rate per initiated cycle (32.84% vs. 28.92%; 1.17% vs 0%) The projected cumulative ongoing pregnancy rate compensating for double counting in case subjects have more than one pregnancy is not different (42.58% vs. 39.84%).ConclusionsDespite lower fresh transfer rates, elective single blastocyst transfer yields a similar projected cumulative ongoing pregnancy rate as in a policy with cleavage stage or blastocyst transfer depending on a good quality embryo count on day 3.
Highlights
Single blastocyst transfer has the advantage of maximizing the fresh single pregnancy rate
It has been established that the significantly lower pregnancy rate achieved after single cleavage stage embryo transfer as compared to a double embryo transfer can be compensated by pregnancies resulting from the first thawed cycle [2]
A Petri-dish containing two 25 μl droplets with thawing solution (TS, 1 M sucrose in Hepes buffered HTF medium supplemented with 20% DSS) was kept at 37°C
Summary
Study design A retrospective cohort study was performed. All fresh IVF or ICSI treatment cycles were performed in a 15 months period from March 2008 until June 2009. The blastocyst was first incubated for 2 min in a 50 μl droplet of HEPES-buffered culture medium. The blastocyst was transferred consecutively into four 25-μl droplets with vitrification solution (VS) containing 15% (v/v) DMSO and 15% (v/v) ethylene glycol. A Petri-dish containing two 25 μl droplets with thawing solution (TS, 1 M sucrose in Hepes buffered HTF medium supplemented with 20% DSS) was kept at 37°C. The blastocyst was transferred to the first of two dilution solution droplets of 25 μl (DS; 0.5 M sucrose in Hepes buffered HTF medium supplemented with 20% DSS) and after that incubated for 2 min in a second DS droplet. The blastocyst was washed in 3 droplets (25 μl) of washing solution (Hepes buffered HTF medium supplemented with 20% DSS), each for 3 min.
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