Changing the start temperature and cooling rate in a slow-freezing protocol increases human blastocyst viability

Abstract

Objective: To determine the effect of start temperature and cooling rate of a slow freezing protocol on human blastocyst viability. Design: Controlled-rate freezing of human blastocysts using different start temperatures and cooling rates. Setting: Private assisted reproductive technology unit. Patient(s): Patients donated with consent cryopreserved pronucleate embryos. Intervention(s): Culture of thawed pronucleate embryos in G III series media, containing hyaluronan, followed by cryopreservation of 36 blastocysts with subsequent noninvasive analysis of embryo metabolism. Main Outcome Measure(s): Pyruvate and glucose consumption and blastocyst reexpansion and quality. Result(s): Glucose con..