Selection of birefringent spermatozoa under Polscope: effect on intracytoplasmic sperm injection outcome

The ideal method for sperm selection during Intracytoplasmic sperm injection (ICSI) is still ill-defined. Identification of a viable spermatozoon amongst immotile spermatozoa for ICSI often becomes difficult. Ninety-six ICSI cycles were selected and divided into Group A (azoospermic, n = 58) and Group B (complete asthenozoospermic, n = 38). Oocytes having birefringent meiotic spindle and zona pellucida thickness <20 mu m were selected for ICSI. Groups A and B were further divided into A1, A2 and B1, B2, respectively, based on the type of ICSI performed. In Group A1, a motile spermatozoon with normal morphology was injected into a metaphase-II (M-II) oocyte. In Group B1, spermatozoon showing coiling of tail following modified hypo-osmotic swelling test was injected into M-II oocytes. In Groups A2 and B2, ICSI was performed by injecting a spermatozoan with birefringent head. Pronuclear morphology, fertilisation rate, embryo grading and pregnancy rate were assessed. ICSI outcome measures were better in Group A2 than in Group A1 but were statistically insignificant. However, significantly higher percentage of Z1 and Z2 zygotes, Grade I and Grade II embryos and pregnancy rate were observed in Group B2 as compared to Group B1. Selection of birefringent spermatozoa shows promising results in asthenozoospermic men and men undergoing testicular sperm aspiration or extraction before ICSI.