Double versus single blastocyst biopsy and vitrification in preimplantation genetic testing (PGT) cycles: protocol for a systematic review and meta-analysis of clinical and neonatal outcomes
Bibliographic record
Abstract
The number of re-biopsied blastocysts is widely increasing in IVF cycles and concerns regarding retesting, which involves double biopsy and vitrification-warming, have been raised. The re-biopsy intervention seems to significantly reduce the pregnancy potential of a blastocyst but the evidence is still restricted to retrospective observational studies reporting a low number of cycles with re-biopsied embryos. Additionally, the neonatal outcomes after the transfer of re-biopsied and re-vitrified embryos are poorly documented to date. A systematic review will be conducted, using PubMed/Medline, EMBASE, Cochrane Central Register of Controlled Trials, Scopus, Web of Science, and Google Scholar to identify all relevant randomized control trials (RCTs), cohort and case–control studies published until December 2024. The participants will include women undergoing preimplantation genetic testing and single euploid frozen embryo transfer (FET) cycles. The primary outcomes are live birth rate (LBR) and singleton birthweight, whereas secondary outcomes are post-warming embryo survival rate, clinical pregnancy (fetal heart pregnancies at 4.5 weeks), miscarriage rate (loss of pregnancy before the 20th week, and stillbirth), preterm birth (PB) rate, small-for-gestational age (SGA, < − 1.28 SDS (standard deviation score)), large-for-gestational age (LGA, > + 1.28 SDS), low birthweight (LBW; birthweight < 2500 g), preterm birth (gestation < 37 weeks), macrosomia (birthweight > 4000 g), pre-eclampsia, eclampsia, perinatal death, and major congenital malformations. Eligible studies will be selected according to pre-specified inclusion and exclusion criteria. Additionally, manual search will target other unpublished reports and supplementary data. At least two independent reviewers will be responsible for article screening, data extraction and bias assessment of eligible studies. A third reviewer will resolve any disagreements. The Newcastle–Ottawa scale (NOS) will be used to assess the quality of the included studies. Studies that receive a score of 7 or higher on the NOS will be considered to have high methodological quality. The extracted data will be pooled and a meta-analysis will be performed. To carry out the data synthesis, a random effects meta-analysis will be conducted using the RevMan software. Heterogeneity will be evaluated by Cochran’s Q test and the I 2 statistics and the strength of evidence will be rated with reference to GRADE. The review and meta-analysis will be reported according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. The findings of this systematic review will be important to clinicians, embryologists, patients, and assisted reproductive service providers regarding the decision-making on retesting embryos for PGT in FET cycles. PROSPERO CRD42024498955.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.042 | 0.059 |
| Meta-epidemiology (narrow) | 0.006 | 0.004 |
| Meta-epidemiology (broad) | 0.032 | 0.035 |
| Bibliometrics | 0.010 | 0.010 |
| Science and technology studies | 0.003 | 0.004 |
| Scholarly communication | 0.007 | 0.007 |
| Open science | 0.004 | 0.005 |
| Research integrity | 0.006 | 0.005 |
| Insufficient payload (model declined to judge) | 0.044 | 0.004 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".