Non-invasive metabolomic profiling of Day 2 and 5 embryo culture medium: a prospective randomized trial

BACKGROUND: Near infrared (NIR) spectroscopy is a technology proposed to facilitate non-invasive screening for the most optimal human embryo for uterine transfer. It has been proposed that the NIR spectral profile of an embryo's spent culture medium can be used to generate a viability score that correlates to implantation potential. As the initial proof of principle studies were all retrospective, our aim was to investigate whether NIR spectroscopy on spent embryo culture medium in an on-site, prospective setting could improve the ongoing single embryo transfer (SET) pregnancy rate after Day 2 and 5 transfers. METHODS: We conducted a single-centre, double-blinded, randomized controlled trial in which the NIR group was compared with a control group. The primary outcome was the clinical pregnancy rate after 6-7 weeks of gestation per randomized patient. In the control group embryo selection was based only on traditional morphological evaluation while in the treatment group NIR spectroscopy was added to the morphological evaluation. RESULTS: The study was terminated early as the analysis of the Data Safety Monitoring Board showed a very low conditional power of superiority for the primary outcome. Of the 752 patients calculated to be included in the study, 164 and 163 patients were randomized into the NIR and control groups, respectively. No significant difference in the ongoing pregnancy rate per randomized patient was found between the NIR and the control group, 34.8 versus 35.6%, (P = 0.97). The proportional difference between the study groups mean was -0.8% (95% confidence interval -11.4 to 10.2). CONCLUSIONS: This study shows that adding NIR spectroscopy, in its present form, to embryo morphology does not improve the chance of a viable pregnancy when performing SET. The NIR technology appears to need further development before it can be used as an objective marker of embryo viability.