P-766 A systematic review and standardized clinical validation of re-vitrification and/or re-biopsy of human embryos for preimplantation genetic testing (PGT): the REPEAT study
Authors: Petrone P , Li Piani L , Brutto M , De Vos A , De Rycke M  D R , Verdyck P , Fernandez-Gallardo E , Berckmoes V , Keymolen K , Roelens C , De Munck N , Hes F , Conforti A , Cimadomo D , Verpoest W 
Published: July 2024

Study question

When needed for PGT purposes, is a second biopsy and/or vitrification associated with lower reproductive outcomes?

Summary answer

Double biopsy and double vitrification (DBDV) is associated with lower live birth rate (LBR) per transfer (4 studies, OR 0.59, 95% CI 0.40-0.87, I2=11%, p = 0.008).

What is known already

PGT requires trophectoderm biopsy and vitrification to prevent the transfer of embryos affected from monogenic conditions and/or chromosomal defects. In 2-6% of biopsy procedures, the diagnosis might be inconclusive because of DNA amplification failure or non-concurrent results. In these cases, a round of warming, re-biopsy and re-vitrification is required. In other cases (i.e., the IVF center implements PGT and/or the patients develop an indication to this procedure), cryopreserved untested embryos might be warmed, submitted to a first biopsy and then re-vitrified.

Study design, size, duration

A systematic-search was conducted in PubMed/Scopus up to November-2023 to retrieve all publications focused on double biopsy and/or double vitrification in PGT cycles, including PGT-M, PGT-SR and PGT-A.

We searched original works in peer-reviewed journals published in English. PRISMA guidelines were followed. PICO-model and ROBINS-I scoring for bias were adopted. The primary outcome was LBR per transfer.

The main secondary outcome was clinical pregnancy rate (CPR) and miscarriage rate (MR) (&lt;22 weeks) per clinical pregnancy.

Participants/materials, setting, methods

Statistical analysis was carried out using Review Manager 5.4. Categorical data were combined with a pooled odds-ratio (OR) with 95% confidence interval (CI). The random-effect model was used for meta-analysis. Between-study heterogeneity was addressed using I2. P-values &lt;0.05 were considered significant.

Main results and the role of chance

Overall, we retrieved 3357 studies. Among them, 3322 were excluded because duplicates or not meeting the inclusion criteria. 35 were scrutinized by two authors independently. Discrepancies were solved by a third author. A total of 7 studies were included and considered for meta-analysis.

Single Biopsy and Double Vitrification (SBDV) was associated with higher MR (5 studies, OR 1.65, 95% CI 1.13-2.42, I2 = 0%, p = 0.009) when compared with Single Biopsy and Single Vitrification (SBSV) group. CPR and LBR were instead comparable.

DBDV was associated with lower CPR (5 studies, OR 0.60, 95% CI 0.45-0.80, I2 = 0%, p = 0.0004) and LBR (4 studies, OR 0.59, 95% CI 0.40-0.87, I2=11%, p = 0.008), and with higher MR (5 studies, OR 1.71, 95% CI 1.04-2.79, I2 = 0, p = 0.03) when compared with the SBSV group.

Limitations, reasons for caution

These associations issue from retrospective assessment based on a limited sample size, therefore the level of evidence is low/very-low. Of note, re-biopsied and/or re-vitrified euploid blastocysts are often transferred to poorer prognosis women who already failed with control embryos. Lastly, limited evidence exists on gestational/neonatal outcomes.

Wider implications of the findings

Improved genetic technologies and operators’ training are essential to minimize inconclusive diagnoses and the putative impact of additional embryo manipulations. Although poorer reproductive outcomes derive from re-biopsy and re-vitrification, they might still be worthwhile to avoid transferring affected/aneuploid blastocysts.

Trial registration number

PROSPERO: CRD42024503678