Development of a new clinically applicable device for embryo evaluation which measures embryo oxygen consumption

Abstract STUDY QUESTION Does a new system—the chip-sensing embryo respiration monitoring system (CERMs)—enable evaluation of embryo viability for potential application in a clinical IVF setting? SUMMARY ANSWER The system enabled the oxygen consumption rate of spheroids, bovine embryos and frozen-thawed human embryos to be measured, and this rate corresponded to the developmental potential of embryos. WHAT IS ALREADY KNOWN To date, no reliable and clinically suitable objective evaluation methods for embryos are available, which circumvent the differences in inter-observer subjective view. Existing systems such as the scanning electrochemical microscopy (SECM) technique, which enables the measurement of oxygen consumption rate in embryos, need improvement in usability before they can be applied to a clinical setting. STUDY DESIGN, SIZE, DURATION This is a prospective original research study. The feasibility of measuring the oxygen consumption rate was assessed using CERMs for 9 spheroids, 9 bovine embryos and 30 redundant frozen-thawed human embryos. The endpoints for the study were whether CERMs could detect a dissolved oxygen gradient with high sensitivity, had comparable accuracy to the SECM measuring system with improved usability, and could predict the development of an embryo to a blastocyst by measuring the oxygen consumption rate. The relationship between the oxygen consumption rate and standard morphological evaluation was also examined. PARTICIPANTS/MATERIALS, SETTING, METHODS We developed a new CERMs, which enables the oxygen consumption rate to be measured automatically using an electrochemical method. The device was initially used for measuring a dissolved oxygen concentration gradient in order to calculate oxygen consumption rate using nine spheroids. Next, we evaluated data correlation between the CERMs and the SECM measuring systems using nine bovine embryos. Finally, the oxygen consumption rates of 30 human embryos, which were frozen-thawed on 2nd day after fertilization, were measured by CERMs at 6, 24, 48, 72 and 96 h after thawing with standard morphological evaluation. Furthermore, the developed blastocysts were scored using the blastocyst quality score (BQS), and the correlation with oxygen consumption rate was also assessed. MAIN RESULTS AND THE ROLE OF CHANCE The device enabled the oxygen consumption rate of an embryo to be measured automatically within a minute. The oxygen concentration gradient profile showed excellent linearity in