Single fresh and frozen-thawed blastocyst transfer using hyaluronan-rich transfer medium.

The purpose of this prospective randomized study was to evaluate use of a hyaluronan-rich transfer medium in fresh and frozen-thawed single blastocyst transfer. The study included 279 single blastocyst transfers in women aged<37 years in their first, second or third treatment cycle. According to the type of single blastocyst transfer (fresh elective or frozen-thawed) the women were divided into two study and two control groups. In both study groups (n=130) transfers were performed using hyaluronan and in the control groups (n=149) a conventional transfer medium was used. The results indicate that fresh elective single blastocyst transfer with hyaluronan results in significantly higher pregnancy rates in a selected subgroup of women; those with >or=2 blastocysts developed to day 5 and a previous implantation failure (55% versus 10%; P=0.012). Overall pregnancy rates after fresh elective and frozen-thawed single blastocyst transfer were similar in both study and control groups.