O-178 Conventional IVF results in better embryo development when compared with ICSI in patients without severe male factor
Authors: Cuquerella M D , Rafael S , Veganzones S , Vidaurreta M , Calventus M I , Cristobal I 
Published: June 2023

Abstract

Study question
Which fertilisation technique offers better embryo development results in patients without severe male factor?

Summary answer
Conventional IVF offers better results regarding embryo development than ICSI in patients without male factor when applying both techniques in the same cohort of oocytes.

What is known already
ICSI was originally indicated for severe male factor. Nevertheless, it is currently used for many other indications so that it has become the most used technique. One of the reasons for the use of ICSI is the fear of a fertilisation failure when using conventional IVF (cIVF).
We have to consider that ICSI is more expensive and invasive. For this reason, it is important to know whether there is a justification to use it in these cases.

Study design, size, duration
It is a randomized prospective study where 68 IVF/ICSI cycles were analysed. The study comprised 812 oocytes and 469 embryos and was conducted from January to December 2022 in the Assisted Reproduction Unit of a tertiary hospital.
In each cycle, we performed a mixed technique using cIVF and ICSI in the same cohort of oocytes.
MII rate, fertilisation rate and embryo development were analysed.

Participants/materials, setting, methods
All consecutive cycles with at least 6 fresh oocytes and semen parameters suitable for cIVF were offered to participate.
In each cycle, oocytes were divided into two groups in order of collection and the fertilisation technique (cIVF or ICSI) was randomly assigned for each group.
All the embryos were cultured to blastocyst stage.
Data of maturity, fertilisation and embryo development were individually registered for every oocyte.
Data were statistically analysed by applying multilevel regression models.

Main results and the role of chance
The patients average age was 36.3±3.0 (28 to 40) and the number of oocytes per cycle was 11.9±5.1 (6 to 26).
396 oocytes (48.8%) were allocated to cIVF group and 416 (51.2%) to ICSI group.
The percentage of mature oocytes was significantly higher in cIVF group than in ICSI group (88.9% vs 81.5%, p = 0.017), which is consistent with the later assessment of maturity in cIVF.
There were no statistically significant differences between cIVF and ICSI groups in terms of fertilisation rate (59.6% vs 56.0%) and high-quality blastocyst rate (A+B) (9.3% vs 8.7%) when analysed per oocyte.
We observed clinical but not statistical differences in blastocyst rate per oocyte (30.6% cIVF vs 23.6% ICSI, p = 0.09). However, blastocyst rate per fertilised oocyte showed statistically significant differences (51.3% cIVF vs 41.6% ICSI, p = 0.047).
Additionally, we found statistically significant differences between cIVF and ICSI in the rate of usable blastocysts (transferred or cryopreserved) per oocyte (26.3% vs 18.3%, p &lt; 0.01) and per fertilised oocyte (44.1% vs 32.2%, p &lt; 0.01).
In 57.8% of the cycles, the best blastocyst was obtained by cIVF and in 42.2% by ICSI.
Fertilisation failure was observed in 3 patients with cIVF and 1 patient with ICSI. All of them had ≤4 mature eggs.

Limitations, reasons for caution
This study includes the 68 patients who met the recruitment requirements until this moment. It is a part of a wider work, which will analyse a higher number of oocytes and pregnancy and perinatal outcomes. For this reason, the sample size is a limitation to the interpretation of the results.

Wider implications of the findings
Our findings encourage the use of cIVF when there is no severe male factor. Considering that cIVF is cheaper and less invasive than ICSI, the exclusive use of ICSI in these patients does not seem to be justified according to our results.

Trial registration number
not applicable