Improving ICSI: A review from the spermatozoon perspective

Area of Science:

• Reproductive Medicine
• Embryology
• Sperm Biology

Background:

• Intracytoplasmic sperm injection (ICSI) is a primary fertilization method.
• Sperm selection is crucial for successful ICSI, especially in difficult cases.
• Novel techniques are emerging to enhance sperm selection and improve outcomes.

Purpose of the Study:

• To critically review current and emerging techniques for sperm handling, preparation, and selection for ICSI.
• To discuss methods for improving sperm motility and chromatin integrity.
• To evaluate techniques for challenging cases, including immotile sperm.

Main Methods:

• Review of techniques including intracytoplasmic morphologically selected sperm injection (IMSI), hyaluronic acid binding, and polarized light microscopy.
• Analysis of methods for assessing sperm chromatin integrity (e.g., annexin V).
• Discussion of strategies for immotile sperm, such as hypo-osmotic swelling test (HOST) and laser assistance, and myoinositol for oligoasthenoteratozoospermic (OAT) men.

Main Results:

• Various techniques exist to improve sperm selection for ICSI, addressing motility, morphology, and chromatin integrity.
• Specific methods like IMSI, HA binding, and annexin V aid in selecting viable spermatozoa.
• Options for immotile sperm and improving outcomes in OAT men are presented.

Conclusions:

• The development of novel techniques for sperm selection in ICSI is promising but requires further validation.
• Many techniques are not yet standard in IVF labs, with experienced embryologists often achieving similar results.
• Large-scale studies are needed to confirm the efficacy and safety of these advanced methods before widespread adoption.