Fresh versus frozen micro-TESE sperm and outcomes

Abstract

The use of fresh versus frozen spermatozoa in men with nonobstructive azoospermia (NOA) undergoing in vitro fertilization (IVF) has been a debated hot topic among reproductive specialists. Each approach presents distinct advantages and disadvantages, with fresh sperm typically showing superior sperm quality, while frozen sperm offers logistical flexibility and a reliable backup for repeated cycles. This review summarizes the latest advancements in sperm retrieval and cryopreservation techniques, providing practitioners with a comprehensive analysis of each option's strengths and limitations. Comparative studies indicate that, although fresh sperm often has better quality metrics, cryopreservation methods such as vitrification have significantly improved postthaw outcomes, making frozen sperm a viable choice in assisted reproductive technologies (ART). The findings show comparable rates for fertilization, implantation, clinical pregnancy, and live birth between fresh and frozen microdissection testicular sperm extraction (micro-TESE) sperm in many cases, although patient-specific factors such as timing, cost-effectiveness, and procedural convenience should guide the final decision. Ultimately, the choice of using fresh or frozen sperm should align with the individual needs and conditions of patients. This tailored approach, supported by the latest advancements, can optimize ART outcomes and provide personalized reproductive care.

Keywords: cryopreservation; infertility; microdissection testicular sperm extraction; nonobstructive azoospermia; spermatozoa.

Figure 1

Schematic diagram for the workflow of fresh and frozen micro-TESE sperm in ART. (a) In the fresh micro-TESE workflow, the procedure is performed on the same day as oocyte retrieval. Testicular tissue is surgically extracted, and viable sperms are identified and selected under a microscope. These sperms are immediately used for ICSI into the retrieved oocytes. Fertilized oocytes are then cultured to develop embryos, which are transferred to the uterus for implantation and potential pregnancy. (b) Conversely, the frozen micro-TESE workflow involves performing the micro-TESE procedure prior to oocyte retrieval, allowing for cryopreservation of the extracted sperm. After retrieval, viable sperms are identified, treated with cryoprotectants, and stored at freezing temperature. When the couple is ready for an IVF cycle, the sperms are thawed, and the best sperms are selected for ICSI. Fertilized oocytes are cultured into embryos and subsequently transferred to the uterus. Micro-TESE: microdissection testicular sperm extraction; NOA: nonobstructive azoospermia; ART: assisted reproductive technology; ICSI: intracytoplasmic sperm injection; IVF: in vitro fertilization. This figure has been created with license in BioRender (https://BioRender.com/s71z006).