Intracytoplasmic Sperm Injection Using Polyvinylpyrrolidone Versus Hyaluronic Acid: A Prospective Sibling-Oocyte Study

Background/Objectives: Hyaluronic acid (HA) has been proposed as a physiological alternative to polyvinylpyrrolidone (PVP) for sperm immobilization during intracytoplasmic sperm injection (ICSI). This prospective sibling-oocyte study aimed to compare embryological outcomes and morphokinetic parameters between HA and PVP. Methods: A total of 811 sibling-oocytes from 51 ICSI cycles were allocated to the HA group (SpermCatch; n = 377) or the PVP group (10% PVP Solution; n = 434). Fertilization outcomes, cleavage, blastocyst formation, and good-quality embryo development were assessed. Embryo morphokinetic parameters (t2–tB) and an AI-derived embryo score were analyzed in a subset of blastocysts with available time-lapse data. Results: The fertilization rates were comparable between the HA and PVP groups (80.9% vs. 85.3%, p = 0.25), as were the cleavage rates (99.0% vs. 97.0%, p = 0.27). However, the HA group had significantly lower rates of good-quality cleavage-stage embryos (33.4% vs. 47.9%, p < 0.01), blastocyst formation (52.3% vs. 69.9%, p < 0.01), and good-quality blastocysts (49.4% vs. 64.1%, p < 0.01). Morphokinetic timings did not differ significantly, whereas embryos in the HA group showed lower AI scores than those in the PVP group (p = 0.04). Conclusions: In this prospective sibling-oocyte cohort, HA-based sperm immobilization did not improve embryological outcomes compared with conventional PVP-assisted ICSI. Differences observed at the blastocyst stage should be interpreted cautiously and require confirmation in larger, randomized studies with clinical follow-up.