Smarter Selection With PGT
For individuals undergoing in vitro fertilization (IVF), embryo testing has become an increasingly popular option. Known as preimplantation genetic testing (PGT), this process screens embryos for chromosomal abnormalities before transfer into the uterus. The goal is to identify healthy embryos, increase success rates and reduce the risk of miscarriage. While promising, PGT has limitations that fertility patients should understand before opting for this add-on procedure.
Understanding PGT options
Preimplantation genetic testing examines embryos created during IVF for chromosomal abnormalities, such as Down syndrome, that could impact development. Most IVF labs use preimplantation genetic testing for aneuploidy (PGT-A), which looks for missing or extra chromosomes. Preimplantation genetic testing for monogenic disorders (PGT-M) and preimplantation genetic testing for structural rearrangements (PGT-SR) are other screening options. A trusted healthcare provider can advise the patient on which approach is best.
Inside the lab
Testing typically occurs on embryos that reach the blastocyst stage, usually 5-7 days after fertilization. At this point, a small number of cells are carefully removed from the outer layer, which later forms the placenta, leaving the part that becomes the baby untouched. The biopsied cells are sent to a genetics lab for analysis, and results typically take several days to return, depending on the lab’s processes and workload.
Benefits of embryo screening
Early testing may help identify embryos with the highest chance of resulting in a live birth. PGT can reduce miscarriage risk by avoiding the selection of embryos with major chromosomal issues. For patients with recurrent loss, advanced maternal age (AMA), or past IVF failure, screening offers added insight. Selecting genetically normal embryos may also lower the number of transfers needed to achieve a healthy pregnancy.
Limitations to consider
Although PGT is a significant advancement in the field, the test does not guarantee pregnancy and cannot detect all genetic conditions. Some embryos labeled as abnormal may still develop into healthy babies, especially if mosaicism is involved. Mosaic embryos contain both normal and abnormal cells, which can lead to uncertain outcomes. False positives or inconclusive results may also occur, especially in lower-quality samples. Patients should remember that PGT is a screening test, not a diagnostic test, meaning that the results are never 100% guaranteed.
Why lab quality matters
Not all IVF labs use the same equipment, protocols, or analysis techniques. PGT accuracy depends on factors such as biopsy timing, embryologist skill, and the handling of samples. Experienced labs may provide more reliable results. Genetic counselors can help interpret findings and explain any confusing terms, such as mosaic.
Testing provides clarity
Genetic testing provides valuable insights during the IVF journey, especially when utilized thoughtfully. While not perfect, PGT can support embryo selection and improve efficiency in some cases. Choosing a reputable lab and working with specialists ensures results are placed in the proper context. With PGT, more information can help parents-to-be make decisions that will optimize pregnancy outcomes.
