Impact of preimplantation genetic testing for aneuploidies (PGT-A) on first trimester biochemical markers – PAPP-A (placenta-associated plasma protein) and free β-hCG (human chorionic gonadotropin)

Pruebas de screening prenatal para la detección temprana de cromosomopatías

“…La β-hCG es una de las primeras moléculas que secreta el embrión y se puede detectar a partir de los 10 días luego de la implantación, no obstante, el nivel más alto de concentración alcanza desde la semana 10 a la 11. A partir de la semana 12, los niveles de beta β-hCG se equilibran y alcanzan concentraciones de 1 MoM en embarazos euploides (21,22). La PAAP-A es una proteasa que se secreta en la placenta específicamente en las células del sincitiotrofoblasto, luego se transporta a la circulación sanguínea materna y la concentración incrementa a medida que transcurre el tiempo de embarazo (13).…”

Trophectoderm Biopsy Differentially Influences the Level of Serum β-Human Chorionic Gonadotropin With Different Embryonic Trophectoderm Scores in Early Pregnancy From 7847 Single-Blastocyst Transfer Cycles

“…And a lower cutoff value for serum b-hCG in predicting a live birth with PGT appeared only available for blastocysts with poor TE quality (i.e., grade B and C) rather than all embryos. Some investigators previously attempted to explore the impact of TE biopsy on serum b-hCG levels, but reached discordant conclusions; with one of the possible reasons being that subgroup analyses by categorizing the grades of TE were not performed (15,17,18). On the basis of a large sample size, we undertook subgroup analyses by blastocyst TE grade and drew a more nuanced and reliable conclusion.…”

“…In 1991, researchers found decreased hCG secretion in biopsied embryos when more than 10 TE cells were removed (16); and a recent study showed that TE biopsy reduced the level of maternal peripheral blood serum b-hCG in early pregnancy (17). In contradistinction, subsequent retrospective studies drew the conclusion that PGT appeared not to affect the levels of serum b-hCG (15,18). TE scores, based on Gardner's morphological scoring system (19), can reflect junctional tightness of TE cells.…”

“…It is natural to conjecture that blastocysts with high TE scores (representing a larger number of total TE cells and of higher quality), would be less affected by biopsy, and it has been reported that the reproductive potential of blastocysts with poor TE quality were more likely to be affected by biopsy (20). Previous investigators have not considered differences in TE quality when evaluating its impact on serum b-hCG (15,17,18), and this might account for the inconsistency in conclusions. We therefore allocated embryos following their TE scores so as to explore whether serum b-hCG levels were affected by TE biopsy to different degrees in early pregnancy.…”