Influenia de la concentracíon de espermatozoides sobre los resultados de la ICSI

Introduction: It has been proposed the suitability to carry out chormosome analysis in a routine way, on both spermatozoa and embryos derived from pacients with severe male factor (crytozoospermia), since a possible higher chromosome abnormalities incidence would be present that would negatively affect fertility, pregnancy, abortion and live births rates. Objetive: To study the effects of sperm count on ICSI results. Design: Retrospective study of ICSI cycles realized from January 2000 to May 2003 have been considered A maximum of 4 embryos were transferred in each cycle, and at least 2 of those embryos transferred were of grades 1-2. Fertility, implantation, pregnancy, delivery and abortion rates were compared when spermatozoa derived from four different groups, regarding to sperm count in fresh samples: less than 1 million spz/ml (group 1), between 1 and 4 millions spz/ml (group 2), between 5 and 19 millions spz/ml (group 3) and more or equal to 20 millions spz/ml (group 4). Setting: Human Reproduction Service at "La Fe" University Hospital. Results: Group 1 showed a lower fertility rate than the rest of groups, although these differences only reached levels of significance when compared with group 4 (group 1: 72% vs group 2: 80% vs group 3: 79% vs group 4: 87%). Both pregnancy and implantation rates, in group 1, were not only reduced, but also were significantly higher than in group 4 (pregnancy: group 1: 43% vs group 4: 33%; implantation: group 1: 46% vs group 4: 31%; p<0. 05). However no differences were observed among groups on both, delivery (range: 71-76%) and abortion rates (range: 21-36%). Conclusions: The low sperm count does not determine a high embryo loss rate related to a possible higher presence of chromosome abnormalities on those embryos transferred This fact could be explained since ICSI allows the selection and microinjection of normal morphology and motile spermatozoa, and therefore the probability to show chromosome abnormalities is not related to sperm count.