Morphological systems of human embryo assessment and clinical evidence

Abstract

Success rates with IVF have improved remarkably since the procedure was first established for clinical use with the first successful birth in 1978. The main goals today are to perform single-embryo transfer in order to prevent multiple pregnancies and achieve higher overall pregnancy rates. However, the ability to identify the most viable embryo in a cohort remains a challenge despite the numerous scoring systems currently in use. Clinicians still depend on developmental rate and morphological assessment using light microscopy as the first-line approach for embryo selection. Active research in the field involves developing non-invasive methods for scoring embryos and ranking them according to their ability to implant and give rise to a healthy birth. Current attention is particularly being focused on time-lapse evaluation. Available data from preliminary studies indicate that these systems are safe;prospective data now need to be collected to determine whether these methods do improve implantation rates. This review gives brief consideration to the use of morphological evaluations in assisted reproduction treatment, discusses the types of embryo scoring,digital imaging and biometric approaches currently in use and comments on future developments for embryo evaluation.

Histidine-rich glycoprotein derived peptides affect endometrial angiogenesisin vitrobut has no effect on embryo development

“…Time-lapse monitoring of embryos in culture and the evaluation of distinct morphokinetic patterns, monitored by time-lapse methodology such as the EmbryoScope®, might be used as a tool to follow and visualize embryo quality [Kaser and Racowsky 2014;Machtinger and Racowsky 2013;Meseguer et al 2011;Wong et al 2010]. The capacity to develop into a fully expanded blastocyst is a potential indicator of embryo quality and a delayed time to reach blastocyst stage is associated with increased risk of aneuploidy [Campbell et al 2013;Cruz et al 2012].…”

Blastocyst vs cleavage‐stage embryo transfer: systematic review and meta‐analysis of reproductive outcomes

“…from day 3 to day 5-6), embryo self-selection will occur after activation of the embryonic genome on day 3. This, in turn, enables identification of those embryos capable of forming blastocysts in vitro and so, theoretically, should enable selection of those with the highest implantation potential [2][3][4] . Thus, blastocyst transfer may increase the pregnancy rate per embryo transferred, which is especially relevant in the context of single embryo transfer policies intended to reduce multiple gestations 5,6 .…”

Embryo quality but not pronuclear score is associated with clinical pregnancy following IVF

“…Very recently, time-lapse monitoring systems have been developed and early data suggests the precise time of cell division and cleavage pattern are associated with improved implantation and pregnancy rates [32][33][34]. Therefore even if PN score is not predictive, zygote and early embryo division prior to day 3 may still be helpful in predicting embryo potential.…”