Early Detection of Cryogenic Dewar Degradation Using LevelSense™: Longitudinal Temperature Analytics and Data-Driven Risk Stratification in IVF Cryostorage.

BACKGROUND: Cryogenic Dewars used for IVF cryostorage are commonly evaluated through periodic inspections and evaporation measurements, which may delay the detection of insulation degradation or lead to premature Dewar retirement. Conventional failure models emphasize catastrophic vacuum loss; however, field observations suggest that many Dewars exhibit transient or progressive thermal anomalies prior to permanent failure. METHODS: A retrospective observational study was conducted using longitudinal liquid nitrogen (LN2) temperature telemetry data acquired from static IVF cryostorage units operating under continuous clinical conditions. Existing temperature data were evaluated to identify transient deviations, recovery behavior, event frequency, and long-term baseline drift. These features were integrated into a composite Dewar Health Index (DHI) designed to characterize insulation performance and degradation risk over time without direct measurement of vacuum pressure. In parallel, the normal evaporation rate, the steady-state rate of LN2 evaporative loss derived from continuous level telemetry, was evaluated as an independent, energy-based measure of heat leak into the cryogenic system. Trend-based analytics were applied to distinguish temporary disturbances from progressive and permanent degradation modes. Analyses were performed on randomly sampled, de-identified telemetry drawn from an extensive cryostorage monitoring database comprising over 1000 active zones with continuous 5-minute data acquisition. RESULTS: Cryostorage Dewars exhibited nonbinary thermal behavior, including transient temperature deviations followed by recovery, consistent with known cryogenic phenomena and dynamics. Dewars exhibiting increasing excursion frequency, prolonged recovery times, and sustained baseline temperature drift showed patterns consistent with progressive degradation prior to retirement. The DHI differentiated stable, degrading, and high-risk Dewars solely based on longitudinal temperature telemetry. CONCLUSIONS: Longitudinal temperature analytics provide a noninvasive means of assessing the health of cryogenic Dewars in IVF cryostorage applications. The DHI enables early identification of degradation trends and supports risk stratification and maintenance planning without changes to clinical workflows. These findings highlight the value of continuous monitoring and data-driven assessment for improving cryostorage reliability and safety in assisted reproductive technology environments.