What we learned from extended culture of ‘rejected’ day-3 cleavage stage embryos: a prospective cohort study

Abstract

BackgroundTo test whether poor quality day-3 embryos can undergo successful blastulation and implantation.MethodsA prospective cohort study was conducted. Whether or not a good quality embryo was transferred on day-3, poor quality (rejected) embryos were further cultured and followed. The clinical outcome of each embryo was assessed.ResultsA total of 694 rejected embryos (from 205 patients) were included, with a blastulation rate of 21.2% (147 embryos) compared to 64.2% general blastulation rate reported by our laboratory (P < 0.01). In a multivariate logistic regression model, only their grade on day-3 significantly affected blastulation (P = 0.01). A total of 97 embryos attained eligibility for fresh transfer or cryopreservation, only 6 of which resulted from a day-3 embryo scored < 2. Of these, 52 were transferred, resulting in 21 pregnancies (16 clinical and 5 chemical). In summary, 694 cultured embryos yielded 16 clinical pregnancies; a 2.3% clinical pregnancy rate.ConclusionsLow score day-3 embryos can result in successful blastulation and clinical pregnancies. However, the normal blastulation rate is poor.

Miscarriage Rate Is High With Frozen-Thawed Blastocysts Arising From Poor-Quality Cleavage Stage Embryos

“…Recently, the embryo culture systems have improved the efficiency and reliability of obtaining blastocysts in vitro, and PQE have been reconsidered for further developmental potential. Many findings suggest that embryos with low morphological scores can still grow into the blastocyst stage and have a good clinical outcome (3)(4)(5)(6). However, the transfer of a good-quality embryos might improve obstetric and perinatal outcomes (5,6).…”

“…Many findings suggest that embryos with low morphological scores can still grow into the blastocyst stage and have a good clinical outcome ( 3 – 6 ). However, the transfer of a good-quality embryos might improve obstetric and perinatal outcomes ( 5 , 6 ). To the best of our knowledge, few studies have evaluated the possible effects of transferring cryopreserved blastocysts arising from poor-quality cleavage stage embryos on pregnancy and perinatal outcomes.…”