BLASTOCYST "PUMPING" IS A DETRIMENTAL FEATURE PREDICTING IMPLANTATION FAILURE: HIGHLY ACCURATE ASSESSMENT BY COMPUTER VISION ANALYSIS OF TIME-LAPSE VIDEOS

Abstract

To determine for the first time, whether "pumping" or "weak contraction," defined as blastocoelic contraction by more than 8 microns in diameter, is associated with poor implantation rates, independent of other morphokinetic features. We analyzed 148,441 images from time-lapse sequences of 317 expanded blastocysts, chosen for transfer, with known implantation data. Using a computer vision algorithm, we were able to measure the blastocyst diameter, approximated to a best-fit circle, in steps of 8 microns. We defined a "pumping event" or a "weak contraction" when the blastocyst diameter was more than 8 microns smaller in diameter when compared to its image taken 40 minutes earlier. We further defined a "major pumping event," when the contraction in blastocyst diameter was greater than 16 microns, vs a “minor pumping event” where it was greater than 8 but no more than 16 microns. We also defined an "early pumping event" when it occurred as the blastocyst was up to 140 microns in diameter vs a “late pumping event” where the blastocyst was over 140 microns. The extent, number of pumping events, and the stage of blastulation at which it occurred were measured and compared to the embryos’ known implantation outcomes. Of the 317 blastocysts, 188 (59.3%) successfully implanted. Of the 188 blastocysts that implanted, early pumping was noted in 27 (14%) blastocysts, for a total of 73 events, at average ± SD 110.7±4.2 hours. Early pumping events occurred in 22 (17%) of the 129 blastocysts that failed to implant with overall 80 events at average ± SD 112.0±4.8 hours. Major pumping events occurred 25 times in 14 (7%) blastocysts that implanted at average ± SD 110.5±7.7 hours vs. 38 events in 18 (14%) blastocysts that failed to implant, at average ± SD 111.7±4.6 hours. Major pumping events were significantly correlated with implantation failure (OR 1.87, P=0.03, for at least one major pumping event, OR 2.42, P=0.04 for at least two major pumping events). Multiple early pumping events significantly correlated with implantation failure (OR 2.07, P=0.02, for at least three early pumping events, OR 2.55, P=0.02, for at least four early pumping events). Weak blastocyst contractions can be defined and accurately measured using computer vision algorithms. These algorithms allowed us to measure changes in blastocyst diameter with unprecedented accuracy of 8 microns. Multiple "early" or "major" pumping events were found to be uncommon, but when they occur, they are strongly predictive of implantation failure. Therefore, blastocysts should be preferably deselected if they exhibit this behavior.