Fertility Associates, 7 Ellerslie Racecourse Drive, Remuera, Auckland 1051, New Zealand.
Department of Obstetrics and Gynaecology, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Rd, Grafton, Auckland 1023, New Zealand.
Hum Reprod. 2018 Jun 1;33(6):991-997. doi: 10.1093/humrep/dey091.
Extended culture to the blastocyst stage is widely practised, improving embryo selection and promoting single embryo transfer. Selection of useable blastocysts typically occurs on Days 5 and 6 of embryo culture. Embryos not suitable for transfer, biopsy or cryopreservation after Day 6 are routinely discarded. Some embryos develop at a slower rate, however, forming blastocysts on Day 7 of culture. Day 7 blastocysts can be viable, they can be of top morphological grade, euploid and result in a healthy live birth. Since ending culture on Day 6 is current practice in most clinics, viable Day 7 blastocysts may be prematurely discarded. Although Day 7 blastocysts make up only 5% of useable blastocysts, those which are suitable for cryopreservation or biopsy are clinically significant. Overall, culturing embryos an additional day increases the number of useable embryos per IVF cycle and provides further opportunity for pregnancy for patients, especially those who have only a few or low-quality blastocysts.
囊胚培养被广泛应用，能够提高胚胎选择的准确性并促进单胚胎移植。通常在胚胎培养的第 5 天和第 6 天选择可利用的囊胚。第 6 天以后不适合进行移植、活检或冷冻保存的胚胎会被常规丢弃。然而，一些胚胎发育速度较慢，在培养的第 7 天形成囊胚。第 7 天的囊胚可以是有活力的，它们可以具有最佳的形态学等级、整倍体，并且能够导致健康的活产。由于目前大多数诊所都在第 6 天结束培养，有活力的第 7 天囊胚可能会被过早丢弃。尽管第 7 天的囊胚仅占可利用囊胚的 5%，但那些适合冷冻保存或活检的囊胚具有重要的临床意义。总体而言，额外培养一天胚胎会增加每个 IVF 周期的可用胚胎数量，并为患者提供更多的妊娠机会，尤其是那些只有少数或质量较低的囊胚的患者。
