Comparative study of intracytoplasmic sperm injection using the traditional holding and the oocyte-holding pipette without aspiration.

Despite the high level of standardization of the intracytoplasmic sperm injection (ICSI) technique, there are some aspects that deserve special attention and should still be improved. The major drawback of the technique is its invasiveness, as during cytoplasmic aspiration different structures of the oocyte may be lost or damaged. This is partly because the microtools used in ICSI were not specially designed for assisted reproduction but for other medical-biological disciplines. In view of the above caveats, the aim of the study was to compare the results of ICSI with the traditional oocyte-holding pipette and the oocyte-holding pipette without aspiration (PiWA). In total, 155 patients and 1037 oocytes were included in the study. In each ICSI cycle, half of the oocytes were microinjected using a traditional holding pipette and the other half using a PiWA. In result, the PiWA technique produced a significant increase in the fertilization rate: 88.12% (95%CI: 84.62-90.92%); holding pipette: 73.33% (95%CI: 68.72-77.49%). Also, it produced a significant decrease in the embryo degeneration rate compared with the traditional holding pipette [PiWA: 2.07% (95%CI: 1.11-3.8%); holding pipette: 4.51% (95%CI: 3.06-6.59%)]. Pregnancy rate depended on the holding technique used, both in single embryo transfers (n = 59; χ2 = 4.608; P-value = 0.032) and double embryo transfers (n = 156; χ2 = 4.344; P-value = 0.037); with PiWA presenting a significantly higher pregnancy rate than the traditional holding technique. Based on current evidence and the present results, improvements should focus on decreasing the invasiveness of the microinjection itself by minimizing or avoiding aspiration and cytoplasmic disorganization, as is successfully achieved with PiWA.

A new oocyte-holding pipette for intracytoplasmic sperm injection without cytoplasmic aspiration: An experimental study in mouse oocytes.

We assessed the feasibility of using a new oocyte-holding pipette (pipette without aspiration, PiWA) for intracytoplasmic sperm injection (ICSI), which prevents cytoplasmic aspiration during microinjection. A pilot experimental study in eight mature mouse oocytes to assess the feasibility of the oocyte-holding PiWA for ICSI procedure. The absence of oocyte degeneration after microinjection and the viability of correct embryo development were also evaluated. The pipette comprises a suction conduit inside an elongated cylindrical body and a funnel-shaped working end, which is dimensioned to hold the oocyte in a tight-fitting manner. Upon aspirating via the suction conduit, the oocyte remains partially trapped inside the funnel and becomes deformed changing the spherical shape of its resting state to an oval shape that tensions the surface and increases the turgor. In all ICSI procedures using the new PiWA, the oocyte membrane presented some resistance but was easily broken when exerting some pressure or small aspiration. The eight oocytes developed, six of which reached the blastocyte stage. The results obtained in this study indicate that the increase in oocyte membrane turgidity caused by PiWA prevents vigorous aspiration of the cytoplasm during spermatozoa microinjection.