PICSI vs ICSI compared Using Sibling Oocytes

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PICSI vs ICSI compared using sibling oocytes

SUMMARY: PICSI VS ICSI

In this study comparing PICSI to ICSI using sibling oocytes, PICSI resulted in significantly higher fertilization rates (82.2% vs 70.5%), transfer eligible embryo rates (51.1% vs. 38.1%), and a greater number of high quality embryos, compared to ICSI.

doi.org/10.1111/andr.12982

Background

Intracytoplasmic sperm injection (ICSI) is currently used in approximately half of all in vitro fertilization (IVF) treatments worldwide.

This involves the selection of a single sperm cell, based on its motility and morphology alone by an embryologist. Over the years several methods, including hyaluronic acid binding ICSI (HA-ICSI), have been developed to help choose the ideal sperm cell based on other criteria.

HA-ICSI works on the principle that mature and structurally sound sperm bind to hyaluronic acid commonly found in cells along the perimeter of the egg. Physiologic ICSI (PICSI) dish and SpermSlow methods are the two most common which utilise hyaluronic acid binding for ICSI.

Although being used in clinics for over a decade, the benefits of HA-ICSI remained debated among researchers. A recent Cochrane review reported no difference in live birth rates, compared to standard ICSI, even though it acknowledged a potential decrease in miscarriage rates.

These conflicting results are most likely the result of inherent study design limitations, such as selecting couples from the general IVF population without indications for ICSI and comparing different groups of couples with potentially confounding factors.

To overcome these limitations, researchers recently suggested using sibling oocytes, i.e. single patient oocytes retrieved during a single procedure, randomly fertilised by ICSI and PICSI.

Methodology

A total of 552 sibling oocytes were randomly fertilized by both ICSI and PICSI at Hadassah Mount Scopus between January 2017 and April 2020. Ovarian stimulation protocols included Gonadotrophin Releasing Hormone (GnRH) antagonist and both long or flare up GnRH agonist. Oocyte maturation was achieved using hCG, GnRH agonist or both followed by oocyte collection 36 to 38 hours later.

Next oocytes were randomly and evenly assigned to each fertilization method wherever possible, however in some cases too few sperm were selected by hyaluronic acid binding to fertilize half the retrieved oocytes. In these instances, the remainder of oocytes were fertilized by standard ICSI.

Fertilization rate was defined as the number of 2PN fertilized oocytes with eligible cleavage stage embryos (Graded ≥ B/C, Istanbul consensus) and blastocysts (Graded ≥ BC / CB) transferred between day 2 and 5.

Results

Cohort characteristics showed that male factor (62.3%) and unexplained infertility (33.3%) was the most common reason for IVF treatment among couples.

Following oocyte retrival, the number of oocytes fertilized by PICSI and ICSI was 294 and 257 respectively.

Initial analysis of primary and secondary outcomes showed significantly higher fertilization (82.8% vs 70.5%) and transfer eligible embryo rates (51.1% vs 38.1%) among the PICSI fertilized oocytes.

Based on embryo grades alone, PICSI fertilized embryos was transferred more often (53% vs 28%), with remaining cycles using one embryo from both methods.

Comparing the biochemical and pregnancy rates, in couples where only one PICSI or standard ICSI fertilized embryo was transferred, no statistically significant difference was found, in part due to the small number of embryo transfers (n=44).

The authors noted that ideally transfer of all embryos would allow comparison of PICSI vs ICSI in patients own embryos, however this is impractical as cryopreserved embryos may take years to transfer or not be transferred at all.

Limitations

  1. Retrospective study.
  2. Small number of embryo transfers.

Funding

No external funding was declared for this study.

Glossary

Agonist
A substance (drug) that causes the same action as the normal substance.

Antagonist
A substance (drug) that stops the action or effect of another substance.

Blastocyst
A fertilised embryo that has developed an inner cell mass and outer layer (trophoblast) some time from day 4 onwards.

Cleavage
The division of cells, from the 2-cell stage to 16-cell stage, beginning on day 2.

Oocyte
Unfertilised immature / mature egg.

Similar studies

Liu Y, et al. (2019). Intracytoplasmic sperm injection using hyaluronic acid or polyvinylpyrrolidone: a time-lapse sibling oocyte study. https://doi.org/10.1080/14647273.2017.1366077

Miller D, et al. (2019). Physiological, hyaluronan-selected intracytoplasmic sperm injection for infertility treatment (HABSelect): a parallel, two-group, randomised trial. https://doi.org/10.1016/S0140-6736(18)32989-1

Erberelli R F, et al. (2017). Hyaluronan-binding system for sperm selection enhances pregnancy rates in ICSI cycles associated with male factor infertility. https://doi.org/10.5935/1518-0557.20170002

Mokánszki A, et al. (2014). Is sperm hyaluronic acid binding ability predictive for clinical success of intracytoplasmic sperm injection: PICSI vs. ICSI? https://doi.org/10.3109/19396368.2014.948102


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