Sperm defect severity rather than sperm source is associated with lower fertilization rates after intracytoplasmic sperm injection

Abstract

To evaluate the impact of sperm deficiencies and sperm source on the outcome of ICSI. Retrospective analysis of laboratory and clinical data. This study included 313 ICSI cycles performed from January 2002 to November 2003. Cycles were divided into two major groups according to the source of spermatozoa: Ejaculated (group I; n=220) and Testicular/Epididymal sperm (group II; n=93). Group I was subdivided into four groups according to the severity in the abnormality of the semen analysis: single defect (oligo-[O] or astheno-[A] or teratozoospermia[T], n=41), double defect (a combination of two single defects, n=45), triple defect (OAT, n=48), and control (no sperm defects; n=86). Group II was subdivided according to the cause of azoospermia: obstructive (OA: n=39) and non-obstructive (NOA: n=54). Sperm selection and microinjection were performed by a single operator using 400X magnification. Female age, mean number of oocytes retrieved, mean number of MII oocytes and mean number of embryos transferred were not statistically different among groups. Fertilization (2PN), cleavage, good embryo quality, clinical pregnancy and abortion rates were statistically compared using one-way ANOVA and Chi Square analyses, with P<0.05 considered significant. Significantly lower fertilization rates were obtained when either ejaculated sperm with triple defect or testicular sperm from NOA patients were used for ICSI as compared to other groups (Table 1, P<0.05). Epididymal and testicular spermatozoa from OA patients fertilized as well as normal or mild/moderate deficient ejaculated sperm. Cleavage, good embryo quality, pregnancy and abortion rates did not differ statistically between ejaculated and obstructive azoospermia groups. However, fertilization, cleavage and pregnancy rates were significantly lower for NOA patients. ICSI is a formidable therapy that can help most cases of male infertility. However, it bypasses pathological obstacles of the spermatozoa as a messenger rather than problems concerning the spermatozoa as a carrier. Lower fertilization potential is to be expected when ICSI is performed with spermatozoa from men with severe deficiencies, such as those with triple sperm defect and NOA. Such individuals may have increased genetic risks relative to other male factor conditions and their spermatozoa harbor defective messages that will not contribute to the development of a normal zygote.