Spindle position assessment prior to ICSI does not benefit fertilization or early embryo quality

Intracytoplasmic sperm injection (ICSI) is traditionally performed with the first polar body at 6 or 12 o'clock, and the injection pipette inserted at 3 or 9 o'clock. This positioning aims to direct the path of the injection pipette at a distance from the presumed metaphase II spindle position. Since spindles can now be imaged directly in living oocytes using computer-assisted polarized light microscopy, the effectiveness of this positioning precaution was studied. Patients undergoing oocyte collection and ICSI had their oocytes non-invasively imaged for spindles prior to ICSI. The spindle position relative to the first polar body at 6 o'clock was assessed using an analogue clock face as an approximation. Fertilization and embryo quality were recorded blind to spindle position. Polar body displacement and spindle position at ICSI did not significantly affect fertilization or embryonic quality. The highest frequency of normally fertilized oocytes and good quality embryos developed from oocytes with spindles located in or near the plane of injection at ICSI (the 3, 4, 8 and 9 o'clock positions). This study questions the usefulness of spindle imaging and the relevance of positioning the first polar body at 6 o'clock during ICSI.