Embryos can remain viable in storage for many years, even decades, under certain conditions. Factors that affect the duration of viability for stored embryos include the method of cryopreservation used, the quality of the embryos at the time of freezing, the storage conditions, and the expertise of the fertility clinic handling the process.

1. Cryopreservation Method: The method of freezing embryos plays a crucial role in their long-term viability. There are two main techniques used for embryo cryopreservation: slow freezing and vitrification. Vitrification is generally considered more effective in preserving the viability of embryos during storage.

2. Embryo Quality: The quality of the embryos at the time of freezing is crucial for their long-term viability. Higher quality embryos have a better chance of surviving the freezing and thawing process and maintaining viability during storage.

3. Storage Conditions: The storage conditions, including temperature stability, storage media, and security measures, can impact the viability of stored embryos. Embryos need to be stored in specialized cryogenic tanks at very low temperatures to maintain their viability.

4. Fertility Clinic Expertise: The expertise of the fertility clinic in handling the cryopreservation process and managing the storage of embryos is vital. Clinics with experienced embryologists and strong quality control measures are more likely to maintain the viability of stored embryos for longer periods.

In general, embryos can remain viable in storage for many years, with reports of successful pregnancies from embryos stored for over a decade. However, it