P-227 ICSI outcomes after using in-situ microfluidics of fluidic walls versus DGC: a prospective non-inferiority comparative pilot study in sibling oocytes
Authors: Ferrer Buitrago M , Ferrer-Robles E , Muñoz-Soriano P , Antequera-Durán V , Gómez-Giménez B , Bataller-Sánchez J J , Barberà-Alberola A , Calatayud-Lliso C , Ruiz-Jorro M 
Published: June 2023

Abstract

Study question
Does the novel strategy in-situ microfluidics (isM) yield comparable ICSI outcomes to the control sperm selection methodology density gradient centrifugation (DGC)?

Summary answer
ICSI outcomes show that handmade in-situ microfluidics of fluidic walls are as effective as DGC to achieve fertilization and usable day 5 blastocyst formation rate.

What is known already
Microfluidics technologies are proving their capability to select suitable sperm for ICSI. Increasingly, publications show novel and ingenious microfluidics strategies aimed to integrate sperm biomimicry during in vitro sperm selection while simplifying the IVF-workflow. We recently designed a microfluidics system which allows selecting sperm for ICSI in the same ICSI-dish, only using microfluidics and disregarding centrifugation, washing and plasticware. A previous proof-of-concept study showed that this methodology was efficient to select suitable sperm for ICSI as it could separate at least 20 progressive spermatozoa in less than 15 minutes in a clean microdroplet free of any remaining seminal plasma.

Study design, size, duration
The present pilot study included a total of 280 fresh MII-oocytes allocated in a 1:1 ratio to the study (isM-ICSI) and control (DGC-ICSI) groups. The statistical power was established at 80% at a CI 95%. For comparison we relied in the KPIs: ICSI normal fertilization rate (INFR) and Day 5 usable blastocyst rate (D5UBR). The non-inferiority margin (Δ) was established using 2-sigma warning limit and our historical control mean values (ΔINFR = 7% and ΔD5UBR = 10%).

Participants/materials, setting, methods
An informed consent was signed by all participants. The comparative study included 29 consecutive ICSI cases performed in fresh oocytes from women under 40 years old and with an oocyte yield ≥6 MII. All semen samples had ≥1 × 106/ml progressive spermatozoa and were split into three aliquots: 1-seminogram (100 µl), 2-isM (10 µl), 3-DGC (surplus). Embryos were cultured in bench-top Time-lapse incubators, using GTL-media under 6,4% CO2 and 5% O2 conditions up to blastocyst stage.

Main results and the role of chance
Sperm characteristics showed the following total mean values for total concentration (42,83 ± 31,1 × 106/ml), total motility (51,28 ± 14,16 %) and progressive sperm concentration (17 ± 12 × 106/ml). The mean number of MII per patient was 9,66. From the total number of oocytes (n = 280), 139 were allocated to isM (study group) and 141 to DGC (control group) groups. INFR was 72,0 % vs 76,6 %, respectively. Non-significant differences were observed (p = 0,54). We observed that the mean total number of usable blastocysts (day 5/6) per patient was 1,83 (53/29) in isM vs 1,66 (48/29) in DGC. Moreover, D5UBR was 53,0% vs 44,4 % (p = 0,26) with a difference between the study and the control of within the non-inferiority margin. We observed a lower rate of arrested embryos (up to day 6) in the study group (19,0% vs 30,0%), although results were not statistically significant (p = 0,08).

Limitations, reasons for caution
This pilot study includes a limited number of oocytes. The present isM protocol depends on a free-hand preparation. Although the use of templates and the training reduces inter and intra-operator variability, a ready-to-use surface would benefit the operability. Further investigation is required to evaluate clinical pregnancy and live birth outcomes.

Wider implications of the findings
Sperm DNA fragmentation is cited among the causes of embryo arrest. As the use of isM resulted in a lower proportion of arrested embryos, exploring its capacity to select non-fragmented sperm warrants further interest. The isM protocol streamlines sperm selection for ICSI, reduces costs and risks along the procedure.

Trial registration number
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