O-074 Whole genome amplification (WGA) of blastocoelic fluid (BF) as an additional criterion for the selection of the most viable embryo
Authors: Albanese C , Magli M C , Perruzza D , Terzuoli G , Azzena S , Crippa A , Tabanelli C , Gianaroli L 
Published: June 2022

Abstract

Study question
Is the presence or absence of DNA in the blastocoelic fluid detected by whole genomic amplification (WGA) a valid method to prioritize embryos for transfer?

Summary answer
Blastocysts with DNA in the BF have lower ongoing pregnancy rates compared with blastocysts without DNA, both in PGT-A and in conventional IVF cycles

What is known already
The detection of DNA in BFs from expanded blastocysts has been reported in different studies. After amplification, this DNA can be analyzed to provide information on the blastocyst chromosome condition, but the degree to which it is representative of the corresponding embryo ploidy is still controversial. The reason of this divergence could reside in several factors, including the different status of the studied embryos. A recent study comparing euploid and aneuploid blastocysts reported a significantly higher incidence of failed BF-DNA amplification in euploid blastocysts compared with aneuploid blastocysts suggesting an effect of the embryo ploidy condition on BF content

Study design, size, duration
This prospective study included 142 cycles with PGT-A (Group-1; 24-chromosome analysis was performed on trophectoderm (TE) biopsies) and 121 conventional IVF consecutive cycles (Group-2) treated in the last three years. In both groups, the BF was collected from expanded blastocysts before vitrification, and submitted to WGA. Single blastocyst transfers were performed by selecting blastocysts based on BF-WGA results giving priority to those with failed amplification. In Group-1, only TE-euploid blastocysts were transferred

Participants/materials, setting, methods
Patients in Group-1 had a maternal age higher than in Group-2 (36.8±3 vs 34.1±3.5 years). The same protocol of vitrification was used for all patients, and only expanded blastocysts of high grade were included in the study. Amplification after WGA was evaluated by loading an aliquot of the amplified product onto a 1.5% agarose gel. An ongoing pregnancy was defined as a pregnancy regularly ongoing beyond the 16th week of gestation

Main results and the role of chance
In Group-1, a total of 622 blastocysts underwent trophectoderm (TE) biopsy and 261 were euploid. The BF was retrieved from 237 euploid blastocysts and submitted to WGA. Amplification failure resulted in 98 BFs, whereas 139 BF gave a positive amplification. In all, 57 clinical pregnancies resulted, 53 of which were regularly ongoing. 61 transfers were performed with euploid blastocysts with failed BF-WGA, and 81 with positive BF-WGA. When looking at the transfer outcome, the ongoing pregnancy rate was significantly higher for euploid blastocysts with failed BF-WGA (31/61, 50.8%) when compared to those with positive BF-WGA results (22/81, 27.2%, p&lt;0.01). In Group-2, there were 62 clinical pregnancies, 52 of which were ongoing. In relation to the BF-WGA results, the ongoing pregnancy rate showed the same trend of Group-1, and was 20% (52/121) for blastocysts with failed BF-WGA and 59.1% (42/71, p&lt;0.001) for blastocysts with positive BF-WGA

Limitations, reasons for caution
This is a prospective cohort study. The results should be confirmed by a prospectively randomized study

Wider implications of the findings
The presence of DNA in the BF could be indicative of an abnormal embryos that is trying to reach a viable condition. Therefore, failure to detect DNA after BF amplification could represent an additional criterion to select viable embryos for transfer both in PGT-A and in conventional IVF cycles

Trial registration number
Not applicable