When should parental karyotyping be advised?

ASRM (2026): screening for parental balanced structural rearrangements should be offered where an unbalanced structural rearrangement is detected in miscarriage testing, or where no chromosomal testing of miscarriages is available. That is a narrower indication than universal testing, and it follows from making miscarriage chromosome testing the first step. Note that ASRM, ESHRE, ACOG and RCOG have differed here historically — prior ASRM guidance and ACOG recommended routine peripheral karyotyping, while ESHRE and RCOG recommended it only after individual risk assessment or an unbalanced result in products of conception. Arguments against routine testing that ASRM cites: low detection chance with fewer than three miscarriages, negative family history, maternal age above 39, reassuring cumulative live birth rates without ART, cost and technical limitations of karyotype, and the unforeseen psychological impact of the diagnosis on reproductive decision-making. A technical caveat: G-banding karyotype misses small rearrangements. One study of over 1,000 RPL patients found 11.7% had chromosomal abnormalities on low-pass sequencing, of which 40% were undetected by G-banding. G-banding remains the widely available first test. Where a translocation is found, counsel on all options. Observational studies show live birth rates of 70–71% without assisted reproduction, with miscarriage rates of 29–30%. PGT-SR efficiency versus expectant management has not been established. Carriers should be told a balanced translocation substantially reduces euploid blastocyst yield — one study found couples needed on average at least 4.5 blastocysts for a good chance of one euploid embryo.