Does intracytoplasmic morphologically selected sperm injection improve embryo development? A randomized sibling-oocyte study

summary answer: The present study did not show a difference in oocyte fertilization rate, nor in embryo development betweenhigh-magnification intracytoplasmic morphologically selected sperm injection (IMSI) and conventional ICSI. what is known already: The presence of nuclear vacuoles in sperm seems to influence embryo development and more spe-cifically blastocyst formation. The use of high magnification for morphological sperm selection prior to ICSI has been associated with higherpregnancy rates and lower miscarriage rates. study design, size, duration: A prospective sibling-oocyte study was conducted, including 350 ICSI cycles to alleviate maleinfertility. Cycles were included from March 2010 to November 2011. participants/materials, setting, methods: On the day of treatment, a high-magnification sperm morphology wasassessed on at least 200 spermatozoa. Primary endpoints were oocyte fertilization rate and embryo development. Because embryo transferswere not randomized, the clinical outcome (clinical pregnancy rate per transfer cycle) was descriptive. However, the embryologist selectingthe embryos for transfer was blinded for the sperm selection procedure.