Preimplantation Genetic Testing (PGT) is a specialized procedure used during in vitro fertilization (IVF) to analyze embryos for genetic conditions or chromosomal abnormalities before transfer. PGT involves taking a tiny biopsy of cells from an embryo, which are then sent to a genetic laboratory for analysis. The results are important for selecting the most viable embryos, and patients often find the waiting period to be stressful. Clarifying the expected timeline helps patients plan their subsequent frozen embryo transfer cycle.
Typical Timeline for Receiving Results
The standard turnaround time for receiving PGT results is seven to fourteen days following the embryo biopsy. This timeframe applies to common tests, such as PGT for Aneuploidy (PGT-A), which screens for an abnormal number of chromosomes. The waiting period begins once the biopsied cells are sent from the fertility clinic to the genetics laboratory for processing.
Some laboratories offer an expedited service, shortening the wait to five to seven days. Conversely, the timeline can extend to three or four weeks if the testing involves more complex genetic analyses. Since a fresh embryo transfer is not possible while waiting for results, the embryos are cryopreserved immediately after the biopsy, and the transfer is scheduled for a subsequent cycle.
The Laboratory Process
The time required for PGT results reflects a multi-step laboratory process executed with precision. After a small sample of cells (trophectoderm) is removed from the embryo, it is prepared for shipment to a specialized genetic testing facility. This logistical step requires careful handling to ensure the integrity of the cells upon arrival.
Once at the facility, the minute amount of DNA must undergo whole genome amplification (WGA) to create enough material for reliable testing. Following amplification, the sample proceeds to the genetic sequencing and analysis phase, often utilizing advanced technology like Next-Generation Sequencing (NGS).
Sequencing maps the genetic material to identify chromosomal errors or specific gene mutations. The resulting raw data is processed through a bioinformatics pipeline for interpretation by specialized genetic scientists. The final stage involves quality control, where the data is reviewed to ensure accuracy before a clinical report is generated and released to the patient’s fertility clinic.
Factors That Influence Result Timing
Several variables can influence the PGT result timeline. The type of PGT being performed is a primary factor, as Preimplantation Genetic Testing for Monogenic disorders (PGT-M) or Structural Rearrangements (PGT-SR) often requires more time than PGT-A. These tests necessitate the development of custom probes specific to the family’s genetic condition, which can add several weeks to the preparatory phase.
Logistical elements, such as shipping and laboratory workload, also influence the turnaround time. Transport of the sample may be delayed if the biopsy occurs just before a major holiday or weekend, or if a high volume of samples creates a temporary backlog at the testing facility.
The quality of the biopsied sample can also cause delays. If the initial cell sample is insufficient or yields an inconclusive result, a re-biopsy of the frozen embryo may be recommended. This retesting adds an entirely new cycle of analysis, typically extending the wait by two to four weeks.