Diagnostic Performance of High-Resolution Next-Generation Sequencing Analyzing Trophectoderm Chromosomal Mosaicism

International Journal of Obstetrics and Gynecology | Vol. 14, No. 9, September 2026 | pp. 1131–1142

DOI: 10.46882/2026/IJOG/000575

Original Research Article

Title: Diagnostic Performance of High-Resolution Next-Generation Sequencing Analyzing Trophectoderm Chromosomal Mosaicism

Names of Authors: Alexander Ivanov¹, Nathalie Dubois²

Authors’ Affiliations:
¹ D.O. Ott Research Institute of Obstetrics, Gynecology and Reproductology, St. Petersburg, Russia
² Service de Biologie de la Reproduction, Hôpital Universitaire de Genève, Geneva, Switzerland

Abstract:
Trophectoderm mosaicism identified during Preimplantation Genetic Testing for Aneuploidies (PGT-A) complicates clinical embryo transfer decisions due to uncertainties regarding embryonic self-correction paths. This prospective diagnostic study evaluated the accuracy and validation tracking of high-resolution Next-Generation Sequencing (NGS) platforms in classifying low-grade (20% to 30%) and high-grade (30% to 50%) chromosomal mosaicism. A total of 1,200 blastocysts underwent trophectoderm biopsy utilizing deep sequencing protocols. To validate diagnostic calls, 120 mosaic blastocysts donated to research underwent total inner cell mass (ICM) disaggregation and secondary multiline re-sequencing, serving as the gold reference standard. Trophectoderm NGS demonstrated an overall sensitivity of 86.4% and a specificity of 91.2% for detecting true ICM chromosomal mosaic lines (AUC = 0.91). Concordance between trophectoderm mosaic designations and true ICM lines was significantly higher for high-grade mosaic calls compared to low-grade designations (84.6% vs. 42.1%, p < 0.001), with low-grade indications showing a high propensity for full inner cell mass euploidy. No technical differences were noted across individual chromosomes. Deep high-resolution next-generation sequencing provides an excellent diagnostic framework for tracking trophectoderm mosaic borders, but low-grade mosaic variants frequently correspond to structurally normal, euploid inner cell masses, advising caution against the routine rejection of these embryos.

Keywords: Preimplantation Genetic Testing; Chromosomal Mosaicism; Trophectoderm Biopsy; Next-Generation Sequencing; Inner Cell Mass; Embryo Selection.

Manuscript Timeline: Received: July 26, 2026; Revised: September 14, 2026; Accepted: September 25, 2026; Published: September 30, 2026.

Citation: Ivanov A, Dubois N. Diagnostic Performance of High-Resolution Next-Generation Sequencing Analyzing Trophectoderm Chromosomal Mosaicism. International Journal of Obstetrics and Gynecology. 2026; 14(9): 1131–1142.

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