PIEZO-ICSI increases fertilization rates compared with standard ICSI: a prospective cohort study

Research question: Is PIEZO-intracytoplasmic sperm injection (ICSI) coupled with a new novel operational fluid (perfluoro-n-octane) superior to standard ICSI? Design: A cohort of patients (n = 69) undertaking microinjection were recruited between January and November 2019 and were then prospectively case-matched. Patients required six or more mature oocytes for inclusion in the study. PIEZO-ICSI uses high-speed microinjection drilling to penetrate the zona and oolemma and deposit the spermatozoa into the cytoplasm, compared with the traditional ‘cutting’ action of ICSI. The primary outcome was fertilization, with secondary outcomes including oocyte degeneration, abnormal fertilization, embryo cryopreservation and embryo utilization. Results: PIEZO-ICSI resulted in significantly higher fertilization rates (80.5 ± 2.4% vs 65.8 ± 2.3%, P < 0.0001) and lower oocyte degeneration rates (4.4 ± 1.3% vs 8.6 ± 1.2%, P = 0.019) and abnormal fertilization rates (2.9 ± 1.1% vs 7.4 ± 1.1%; P = 0.003) compared with standard ICSI. This improvement in fertilization was of most benefit in patients aged ≥38 years. This increase in fertilization increased the number of good quality embryos that were available for cryopreservation/transfer (3.8 ± 0.2 vs 3.1 ± 0.2; P = 0.038), such that patients on average had one extra usable embryo per cycle compared with standard ICSI. There were no differences to Day 5 embryo development or clinical pregnancy from fresh embryo transfer (57.1% PIEZO-ICSI vs 60.0% ICSI) between microinjection methods, although pregnancy outcomes were underpowered. Conclusions: PIEZO-ICSI significantly increased fertilization rates, thereby increasing the number of embryos available for cryopreservation compared with standard ICSI. Further prospective studies assessing cumulative pregnancy rates are warranted.