P–032 Assessment of embryonic developmental outcome of direct unequal cleavage in patients with non-obstructive azoospermia and/or obstructive azoospermia
Authors: NAGANO A , Narumiya Y , Okutani N , Mizuta S , Takeuchi T , Kitaya K , Matsubayashi H , Ishikawa T 
Published: August 2021

Abstract

Study question
Does direct unequal cleavage (DC) affect embryonic development after ICSI with testicular sperm (TESE-ICSI) in patients with non-obstructive azoospermia (NOA) and/or obstructive azoospermia (OA)?

Summary answer
The incidence of DC at the first cleavage (DC1) was extremely high and DC1 negatively affected embryonic development in NOA patients.

What is known already
It has been reported that the blastocyst development of embryos with direct cleavage (DC) was significantly lower than that without DC, but the clinical pregnancy rate after blastocyst transfer was not different with or without DC. The incidence of DC has been reported to be significantly higher after ICSI with testicular sperm (TESE-ICSI) than ICSI with ejaculated sperm (Ej), but to our knowledge, there are few reports investigating that the embryos with DC after TESE-ICSI affect embryonic development.

Study design, size, duration
We conducted a retrospective cohort study using time-lapse incubators (Geri, Genea Biomedx, Australia) from September 2018 to November 2020. Of 1033 two-pronuclear (2PN) embryos from TESE-ICSI, 486 and 547 embryos were from OA (35.9±5.5 years) and NOA (33.7±5.2 years), respectively. As an age matched control, we chose 581 embryos from ICSI using Ej (36.5±4.4 years).

Participants/materials, setting, methods
DC embryos were classified as DC1 (DC at first cleavage), DC2 (DC at second cleavage), and non-DC (without DC). The incidences of DC1 or DC2 and blastocyst development rates were compared among OA, NOA and Ej groups. In TESE-ICSI group, we compared blastocyst development rates with or without DC between good and poor quality embryos on day 3. Good quality embryos were defined as 8 cells with G3 or more by the Veeck’s classification.

Main results and the role of chance
DC1 incidence was significantly higher in NOA (37.3%) than OA (27.8%) and Ej (22.7%) (P &lt; 0.01), whereas DC2 incidence was not statistically different among three groups; NOA (15.7%), OA (15.0%) and Ej (13.4%). Blastocyst development rates in DC1 were 17.8%, 19.5% and 25.8% for NOA, OA and Ej, respectively, which were significantly lower compared to non-DC in corresponding three groups (65.1%, 67.7%, and 68.5%, respectively, P &lt; 0.01). In TESE-ICSI group, good-quality embryo rate on day 3 was significantly lower in DC1 (34.5%, P &lt; 0.01) than DC2 (60.9%) or non-DC (54.2%). Additionally, blastocyst development rates in DC1 and DC2 were significantly lower than non-DC regardless of embryonic grades on day 3 (35.1%, 51.0%, and 81.6% for good-quality embryos on day 3, 10.1%, 27.0%, and 49.1% for poor-quality embryos on day 3, respectively, P &lt; 0.05). When immotile sperm was used for TESE-ICSI, DC1 incidence was 40.0% (6/15), which did not show statistically differences. When performing single frozen-thawed blastocyst transfers, no pregnancies resulted from either DC1 (n = 13) or DC2 (n = 3) embryos in TESE-ICSI group.

Limitations, reasons for caution
We had a few data about the pregnancy rates after blastocyst transfers with DC, because embryos with DC were seldom transferred due to those lower priority. Although DC might be influenced by the sperm, we did not analyze the incidence of DC by taking the semen factors into account.
Wider implications of the findings: The incidence of DC1 was extremely high and DC1 negatively affected embryonic development in NOA patients. Therefore, it is important to observe embryos using time-lapse incubator in order to recognize embryos with/without pregnancy potential, especially for embryos with DC1 in NOA patients.

Trial registration number
Not applicable