Performing ICSI using an injection pipette with the smallest possible inner diameter and a long taper increases normal fertilization rate, decreases incidence of degeneration and tripronuclear zygotes, and enhances embryo development

Purpose. To compare the efficacy of two types of injection pipette used for ICSI, one with a larger (5-7 mum) inner diameter and a shot-ter taper with that inner diametet; and another with the smallest (3-5 mum) possible inne r diameter and a longer taper with that inner diameter. Methods. Retrieved oocytes at metaphase II stage were injected using one of two types of injection pipette, in 33 and 94 cycles, respectively, in a to tal of 127 cycles in 108 patients. Results. In comparison to the injection pipette with a larger (5-7 gm) inne r diameter and a shorter taper with that inner diametet; the injection pipe tte with the smallest (3-5 mum) possible inner diameter and a longer taper with that inner diameter increased normal fertilization rate ((70 +/- 3.6) % vs. (86 +/- 2.2) %; P =.001; mean SEM); decreased the incidence of degene ration ((14 +/- 2.4) % vs. (5 +/- 1.4) %; P =. 001) and tripronuclear zygot es ((1.0 +/- 0.35) % vs. (0.1 +/- 0.21) %; P =. 03); increased Day-2 diploi d embryos ((69 +/- 3.7) % vs. (85 +/- 2.2) %; P =.001) and good-quality Day -2 diploid embryos ((67 +/- 4.0) % vs. (79 +/- 2.4) %; P =. 03), all per in jected oocyte; and increased the number of blastomeres per good-quality Day -2 diploid embryo ((3.0 +/- 0.21 vs. 3.8 +/- 0.12; P=.0003). Conclusions. Performing ICSI using an injection pipette with the smallest ( 3-5 mum) possible inner diameter and a longer taper with that inner diamete r maximizes normal fertilization rate, minimizes the incidence of postinjec tion degeneration and tripronuclear zygotes, and enhances embryo developmen t.