Assessment of the viability of embryos stored in liquid nitrogen produced commercially using culture medium as a complementary test for stereoscopic microscopy.

Summary The objective of the present study was to evaluate the viability of frozen embryos obtained from various private farmers in a culture medium for 4 h. Forty-seven embryos were used that had been previously graded as good and fair. These embryos were evaluated using stereoscopic microscopy by experienced clinicians prior to freezing. Embryos were divided in two groups: the non-cultured group, made up of six good quality embryos, and five fair; and the cultured group that consisted of 20 good quality embryos and 16 fair. Fifty-four per cent of the good quality embryos achieved a favourable development during culture whereas just 42% of embryos determined to be fair were observed to have adequate development. This evaluation was undertaken by serial photographs obtained at the onset of culture and 4 h later. This finding was corroborated by a more specific technique: terminal deoxynucleotide transferase dUTP nick end labelling-bromodeoxyuridine (TUNEL-BrdU). These results are indicative of the necessity of tight quality controls for commercially produced frozen embryos, as once thawed it is unlikely that clinicians will examine them to determine their physiological status prior to transfer.