P-072 Fresh testicular sperm seems to yield more fertilization abnormalities and early pregnancy loss than frozen testicular sperm
Authors: Neifar S , Chtourou S , Braham M , Chakroun M , Debbabi L , Frikha W , Fedhila A , Fadhlaoui A , Chakroun N , Kacem K 
Published: July 2024

Study question

How do ICSI outcomes using fresh testicular sperm, compare to those using frozen samples cryopreserved from the previous fresh testicular sperm extraction (TESE)?

Summary answer

Although fresh testicular sperm led to a better fertilization and pregnancy rate,it yielded more fertilization abnormalities and miscarriages than frozen sperm for the same couples.

What is known already

Testicular biopsies can be performed in cases of severe male infertility to search for spermatozoa. In the current era of advanced reproductive techniques, ICSI in association with TESE may be an effective treatment for patients with azoospermia. TESE could be performed the day of oocyte pick-up, or instead, it may be accomplished previously, and in this case TESE spermatozoa are cryopreserved for the future ICSI cycles. However, when reviewing the literature, not a lot of papers tried to compare the ICSI outcomes between fresh and frozen testicular sperm in the same couples.

Study design, size, duration

This retrospective study included the clinical and embryological data of pairs of fresh and frozen sperm injection cycles from couples after TESE between 2010 and 2023. The first ICSI was performed with fresh spermatozoa retrieved from TESE. The subsequent ICSI cycles used frozen spermatozoa from the first TESE.

Participants/materials, setting, methods

All infertile couples that underwent ICSI+TESE with testicular sperm cryopreservation in the study period were identified (110 couples). Of whom, 34 couples who underwent 40 subsequent ICSI cycle using frozen spermatozoa from the previous TESE were included. ICSI cycles were divided in:

Group 1:ICSI with TESE and fresh testicular sperm injection

Group 2:ICSI with frozen testicular sperm injection

ICSI outcomes were compared for: fertilization/fertilization abnormalities rate, embryo quality, pregnancy and miscarriages rate, and live birth rate.

Main results and the role of chance

The average age of men who underwent ICSI was 42 years, while that of women was 33 years. On average, the couples had their ICSI with frozen sperm within 1.7 years after the TESE. There were no significant differences in women’s clinical parameters, the type of ovarian stimulation used nor its primary outcome between the two ICSI attempts.

Although the primary outcome of ICSI showed a significantly higher fertilization rate for fresh testicular sperm compared to frozen sperm (64.4% vs 44.8%; p = 0.003), there was a tendency for more fertilization abnormalities when fresh testicular sperm was used (8.3% vs 6.2%, p = 0.4).

Despite a better quality of cleavage embryos in ICSI with fresh testicular sperm (43.9% vs 39.2%, p = 0.6) and a higher pregnancy rate for the same group (21.9% vs 15.9%, p = 0.52), the miscarriage rate was twice as high when compared to the miscarriage rate of ICSI with frozen testicular sperm (6.7% vs 3.4%, p = 0.8), indicating that cryopreservation of testicular sperm could play a role in selecting better sperm for micro-injection.

As for the live birth rate, ICSI with frozen sperm led to not statistically inferior rates when compared with ICSI with fresh sperm in the same couples (6.7% vs 10%, p = 0.6).

Limitations, reasons for caution

Due to our inclusion criteria, the study population may seem to be too reduced to reach significant results. To gain more informative insights, we recommend combining results from different centers and referring to the etiology of azoospermia that led to the TESE procedure.

Wider implications of the findings

Genetic testing and chromosomal aberration detection on testicular spermatozoa before and after cryopreservation could be proposed to compare the proportion of defected spermatozoa in both types of samples.

Trial registration number

not applicable