Time-lapse technology is an emerging novel technology introduced into human IVF in recent years and has shown great potential in improving treatment outcomes . Clinical available Time Lapse Imaging systems allow continuous observation of embryo development without removal from controlled and stable incubator condition. First, decreased frequency of handling and exposure of embryos to suboptimal conditions eliminates the risks of stress from temperature changes, high oxygen exposures and pH changes in the culture medium and thus provides improved culture conditions. Second, by serial imaging, more information on embryo development is obtained. TLI allows embryologists to assess the quality of embryos by tracking the timing of events and length of different intervals in embryo development (also refers to as morphokinetic monitoring), adds another dimension to embryo selecting and grading. Until now, a number of studies have been conducted regarding whether morphokinetic variables are correlated with important outcomes such as blastocyst formation, implantation potential, pregnancy potential and even aneuploidy status.
Time-lapse Imaging Systems:
Various time-lapse systems are currently used. Two of the most widely used technologies, the Primo Vision (Vitrolife) and Embryoscope (Fertilitech) systems, both use bright field technology, whereas the EEVA (Early Embryonic Viability Assessment, Auxogyn) system uses dark field technology . All systems incorporate a digital inverted microscope that takes a picture of the embryos at 5-20 minute intervals. The images are processed by custom image acquisition and then displayed on a computer screen. The pictures taken at preset intervals are then connected into short films that can be rewound and fast forwarded for detailed analysis.
Time-lapse culture and evaluation improve IVF success
- Improved implantation rate
Time-lapse improves your chances of transferring a viable embryo, resulting in increased clinical outcome.
- Reduced pregnancy loss
Selecting the most viable embryo for implantation also means reducing the percentage of pregnancies lost or aborted.
- Shorter time to pregnancy
Improving the clinical pregnancy rate while decreasing pregnancy losses effectively shortens the overall time to pregnancy.
LIMITATIONS OF TIME LAPSE IMAGING:
The concept of continuous embryo observation improving IVF outcome seems sound at first look. The technology has been shown to exert no harmful effects on the embryos. The concept, however, has to be proven scientifically before routine clinical application can be recommended. The primary question is: are more observations better than a single daily observation for embryo selection?
The reviewed studies already show promising results but suffer from methodological issues. First, essentially all of the cited studies have a retrospective design. Culture conditions in a given lab (e.g., oxygen tension, culture medium used) could affect embryo development. The genetic integrity of the embryo is, however, expected to have an even more profound effect on the early development of the embryo. During embryo culture, the most crucial task is to differentiate embryos that will implant from those that will not. We can rephrase this statement and say that we need to differentiate the healthy, euploid embryos from the unhealthy, aneuploid embryos. Time-lapse technology has already shown us that euploid embryos follow a much tighter division pattern and aneuploid embryos tend to fall out of range. Therefore, each lab should test whether the proposed kinetic parameters are appropriate for their lab or whether they need to modify them based on their own results rather than adopting them automatically.
It is also well-known that the treatment outcome depends on the stage at which embryo transfer occurs. The different studies used different stage (day 2 to blastocyst stage) transfers, which may interfere with their conclusions regarding the kinetic markers due to their impact on implantation and pregnancy rates.
Time-lapse technology is just one of the methods that is currently being evaluated for embryo selection. None of these technologies are perfect, and rather than looking at them as competing technologies, we should evaluate how they could complete each other and further improve embryo selection during IVF.
In summary, time-lapse technology provides us with a safe, undisturbed, continuous embryo observation option that can aid embryo selection and could be used for research purposes. However, the full benefit of the technology and its place among the other embryo screening tools remains to be determined.
Dr. Ira Biswas.