P–030 A sperm chromatin damage &gt;15% negatively impacts on the quality of embryos obtained from ovum donation ICSI cycles of unselected couples
Authors: Pachec. Castro A , Hervas I , Rivera-Egea R , Gi. Julia M , Navarro-Gomezlechón A , Garrido N 
Published: August 2021

Abstract

Study question
Is embryo quality downgraded in couples with elevated sperm DNA fragmentation (SDF) in the ejaculated semen of male partner using donated eggs?

Summary answer
The rate of good quality embryos at day 3 and blastocyst-stage is statistically inferior in males with SDF&gt;15% undergoing ICSI cycles with donated oocytes.

What is known already
The effect of a damaged paternal chromatin will be shown from the 8-cell stage of embryo development, a time which the genome of the embryo is transcriptionally active. Fertilization with a spermatozoon with fragmented DNA may impair the quality of the embryos obtained per cycle, and therefore reduce the chances of pregnancy. The use of donated oocytes is an ideal model to evaluate the real effect of SDF on embryo quality by standardizing the female factor. In addition, we have a large cohort of ovum donation cases in our history, which allows a more proper evaluation of the effect.

Study design, size, duration
Retrospective multicentric study including the clinical data of 864 couples of ovum donation program who underwent 1903 ICSI cycles between January 2000 and March 2019. The DNA fragmentation of their ejaculated spermatozoa was measured by TUNEL assay (Terminal deoxynucleotidyl transferase dUTP nick end labeling). Two study groups were created according to the SDF level: ≤15% (low) (n = 1626) or &gt; 15% (high) (n = 277).

Participants/materials, setting, methods
Embryos were evaluated throughout embryonic development according to classical morphological parameters at day 3 (D3), on cleavage-stage, and at day 5 (D5), on blastocyst-stage (trophectoderm (TE) and inner cell mass (ICM)), following ASEBIR guidelines, categorized from A to D. Embryos scored as A and B were considered to be good quality. The proportion of embryos was calculated according to the total number of correctly fertilized oocytes or zygotes. A p &lt; 0.05 was considered significant.

Main results and the role of chance
A total of 6130 embryos were evaluated. The SDF average of ≤ 15% group was 5.9% (95%CI 5.7–6.1) and 24.3% (95%CI 23.2–25.3) in the &gt;15% group. The cycle-related characteristics and the seminal parameters were comparable. The proportion of optimal cleavage-stage embryo (number of A+B embryos at D3) per cycle was 21.7% (95%CI 19.0–24.5) (8.1 average cells number, 0.8 embryo fragmentation average, symmetry 1, mononucleated cells) in ≤ 15% SDF group versus 21.1% (95%CI 13.9–28.3) (8.2 cells number average, 1.3 embryo fragmentation average, symmetry 1, mononucleated cells) (p &lt; 0.001). The blastocyst-stage arrival rate (number of embryos at D5) per cycle was higher in the &gt;15% SDF group (p &lt; 0.001), 53.4% (95%CI 48.8–58.1) (TE quality A:20.5%, B:42.5%, C:22.7%, D:14.8%, and the ICM quality A:26.1%, B:52.1%, C:13.2%, D:6.2%) versus 49.9% (95%CI 48.1–51.6) (TE quality A:21.1%, B:42.8%, C:21.85, D:14.1% and ICM A:26.6%, B:55.5%, C:11.1%, D:4.7%) in the low SDF group. The rate of good quality blastocyst (number of quality A+B embryos in D5) per cycle was significantly higher in the couples with low SDF (24.8% (95%CI 23.6–25.9)) than in those with elevated SDF (23.5% (95%CI20.9–26.2)) (p &lt; 0.001). Accordingly, the A+B blastocyst rate divided by the total number of blastocysts was 59.1% (95%CI 56.7–61.4) versus 55.9% (95%CI 49.9–62.0) (p &lt; 0.001), respectively.

Limitations, reasons for caution
The main limitation is that retrospective design of the study may not eliminate the potential unaccounted-for bias derived from the clinical practice of multiple centers even though both groups were statistically comparable. Also, the assessment of embryo quality is still remaining highly subjective to embryologists.
Wider implications of the findings: Although the effect size is small, it may be useful in clinical practice when an ICSI cycle yields no good-quality embryos, as one of the underlying causes of that fact. Knowing the SDF level can be a helpful tool in making subsequent clinical decisions aimed at improving outcomes for couples.

Trial registration number
Not applicable