Design:
Retrospective observational study.
Lee Y, Pinto E, Sim P. Effects of ICSI-Enclosure System on Fertilisation and Utilisation Rate of Gametes and Embryos. Poster presented at the ASPIRE (Asia Pacific Initiative on Reproduction) Conference, 14th Congress, Singapore, 2025. KL Fertility & Gynaecology Centre, Embryology, Kuala Lumpur, Malaysia.
Presented: ASPIRE 2025, Singapore | Last reviewed: August 2026
This page summarises findings from a conference poster presentation based on clinical data from KL Fertility & Gynaecology Centre. It is presented here for the clinical and scientific community and is not intended as a substitute for individualised patient counselling.
Funding and disclosures: No funding declarations are available for this conference poster. The authors report no competing interests.
Background and Aims
Temperature and pH are critical for gamete and embryo survival and development during assisted reproduction. Although in-clinic incubators maintain the required heat and gas conditions, procedures such as intracytoplasmic sperm injection (ICSI) necessarily expose oocytes and sperm to the external environment. Even brief exposure can introduce cellular stress and potentially compromise fertilisation and subsequent embryo development.
An ICSI-Enclosure system addresses this by recirculating warm air and humidified gas at controlled temperatures and concentrations around the micromanipulation workstation, maintaining a physiological environment throughout the insemination procedure. The aim of this study was to evaluate the effect of an ICSI-Enclosure system on two laboratory outcomes: normal fertilisation rate and utilisation rate of gametes and embryos.
Methodology: Study Design and Patient Population
Subjects:
Patients below 38 years of age (mean age: 33 years) who had oocyte retrieval procedures from September 2022 to August 2024 under an antagonist stimulation protocol. Cases where 5 or more oocytes were collected and inseminated through ICSI were included.
Study groups:
Without ICSI-Enclosure (n=75 insemination cycles):
ICSI performed without the controlled enclosure environment.
With ICSI-Enclosure (n=80 insemination cycles):
ICSI performed within the ICSI-Enclosure system, which recirculates warm air and humidified gas at controlled conditions.
The ICSI-Enclosure system was operated by the same embryologists across both periods.
Exclusion criteria:
Gamete donation cycles, preimplantation genetic testing cycles, cases involving surgical sperm retrieval, and cases with severe oligoasthenoteratozoospermia.
Outcome measures:
Normal fertilisation rate: proportion of inseminated oocytes achieving normal fertilisation (2 pronuclei).
Utilisation rate: proportion of inseminated oocytes proceeding to usable embryos. Note: the poster does not explicitly define the denominator or developmental endpoint used for utilisation rate; this should be confirmed with the authors before publication.
Statistical analysis:
Chi-square (χ²) test. Significance threshold: p < 0.05.
Results: Fertilisation and Utilisation Rates With and Without ICSI-Enclosure
Table 1. Fertilisation and utilisation rates by ICSI-Enclosure status
Outcome | Without ICSI-Enclosure (n=75) | With ICSI-Enclosure (n=80) | χ² | p value |
|---|---|---|---|---|
Normal fertilisation rate | 74.8% | 80.3% | 5.59 | 0.02 |
Utilisation rate | 53.9% | 48.2% | 3.15 | 0.08 |
Introduction of the ICSI-Enclosure system was associated with a statistically significant increase in normal fertilisation rate from 74.8% to 80.3% (χ²=5.59; p=0.02, p<0.05). Utilisation rate showed a non-significant reduction from 53.9% to 48.2% (χ²=3.15; p=0.08, p>0.05). The authors attribute the improvement in fertilisation rate to the controlled environment reducing cellular stress on gametes during the insemination procedure. The non-significant reduction in utilisation rate is attributed to individual variation in oocyte quality rather than an effect of the enclosure system.
Discussion: How These Findings Compare With Published Evidence
The significant improvement in fertilisation rate with the ICSI-Enclosure system is consistent with the known sensitivity of gametes to environmental fluctuations during manipulation:
- Temperature deviation during ICSI is a recognised source of cellular stress that can impair spindle integrity and subsequent fertilisation. Maintaining temperature within the physiological range throughout the micromanipulation process is considered a key quality indicator in modern IVF laboratories.
- Published work on the timing of ICSI relative to oocyte denudation demonstrates that environmental consistency during the insemination window materially affects fertilisation outcomes. A 2020 retrospective analysis found that fertilisation rate was significantly associated with the denudation-to-ICSI interval, underscoring how sensitive gametes are to manipulation conditions even within relatively short time windows.
- The ICSI-Enclosure system's mechanism, recirculating humidified gas and maintaining thermal consistency at the workstation level, is directly analogous to the rationale behind closed incubation systems for embryo culture, which have been similarly shown to reduce gaseous and thermal fluctuations that cause oxidative stress.
- The non-significant reduction in utilisation rate (53.9% to 48.2%) is worth noting. While not statistically significant, a numerical decrease in the proportion of oocytes progressing to usable embryos alongside an increase in fertilisation rate could reflect differences in baseline oocyte quality between the two cohort periods, which the retrospective, non-randomised design cannot fully control for. The authors' interpretation, that individual oocyte quality is the likely driver, is plausible but cannot be confirmed without stratified data.
No directly comparable published study specifically evaluating an ICSI-Enclosure system against a control group in the same centre was identified in the current literature, making this study a useful early contribution to a relatively understudied area of IVF laboratory practice.
Clinical Significance
The finding that an ICSI-Enclosure system significantly improved normal fertilisation rate without any adverse effect on oocyte survival or miscarriage risk is clinically relevant for IVF laboratory practice. Every additional fertilised oocyte increases the number of embryos available for selection and transfer, which is particularly meaningful for patients with a limited oocyte yield. The data support adoption of controlled-environment ICSI systems as a laboratory quality improvement measure, with the caveat that a prospective, randomised study would be needed to confirm the benefit and to understand any effect on downstream outcomes such as blastocyst formation rate, implantation rate, and live birth rate.
Limitations of This Retrospective Study
- Retrospective, non-randomised, non-concurrent design: the two groups were drawn from different time periods (before and after introduction of the ICSI-Enclosure system). Differences in patient selection, stimulation protocols, or oocyte cohort quality across periods cannot be ruled out.
- The same embryologists performed ICSI in both periods, which controls for operator variability, but the introduction of any new system introduces a learning effect that cannot be separated from the device effect.
- Raw oocyte counts are not provided in the poster; only percentages are reported, so the absolute number of oocytes fertilised and utilised cannot be independently verified.
- Utilisation rate is not defined in the poster. Without a clear denominator (total oocytes inseminated, or a specific developmental endpoint such as blastocyst formation), the 48.2% and 53.9% figures cannot be precisely interpreted.
- No data are presented on downstream clinical outcomes (blastocyst formation rate, implantation rate, clinical pregnancy rate, live birth rate), so whether the fertilisation rate improvement translates into meaningful patient-level benefit is unknown.
- The sample size is modest (n=75 and n=80 insemination cycles). Statistical power to detect modest differences in utilisation rate, or to subgroup-analyse by oocyte quality or patient characteristics, is limited.
- Conference poster format; findings are not yet subject to full peer-review.
Key Findings
- Use of an ICSI-Enclosure system was associated with a statistically significant increase in normal fertilisation rate from 74.8% to 80.3% (χ²=5.59; p=0.02).
- Utilisation rate showed a non-significant reduction from 53.9% to 48.2% (χ²=3.15; p=0.08), attributed to individual oocyte quality variation rather than a device effect.
- The ICSI-Enclosure system provides a controlled thermal and gaseous environment throughout the micromanipulation procedure, reducing cellular stress on gametes.
- These findings support the ICSI-Enclosure system as a useful laboratory quality improvement tool, particularly for improving fertilisation outcomes.
- Prospective randomised studies are needed to confirm the benefit and assess downstream clinical outcomes including blastocyst formation, implantation, and live birth rates.
About the Team Behind This Research
- Lee Y and Pinto E conducted this research as part of the Embryology team at KL Fertility & Gynaecology Centre.
- Poo Keen Sim is the Chief Embryologist and a member of the Scientific Team at KL Fertility & Gynaecology Centre, with over 20 years of hands-on experience in clinical embryology. She holds a Master's degree in Clinical Embryology and is a co-author of this study.
References
- Lee Y, Pinto E, Sim P. Effects of ICSI-Enclosure System on Fertilisation and Utilisation Rate of Gametes and Embryos. Poster presented at the ASPIRE 2025 Conference, Singapore.
- Nakagawa K, Takeshita N, Nishi Y, et al. Performing ICSI within 4 hours after denudation optimizes clinical outcomes in ICSI cycles. J Assist Reprod Genet 2020;37(5):1153-1159. https://doi.org/10.1007/s10815-020-01709-4
- Ferrer-Buitrago M, Dhaenens L, Lu Y, et al. Human oocyte calcium analysis predicts fertilization and embryo development for ICSI patients. Hum Reprod 2019;34(7):1250-1260. https://doi.org/10.1093/humrep/dez068
- Aleyasin A, Mehdinejad M, Mahdavi A, et al. Predictive factors of in vitro fertilization. Med J Islam Repub Iran 2016;30:457.