P-145 Hyaluronidase concentration and its effect on embryo quality
Authors: Masso Hernaez J , Montalvo V , Garcia-Faura A , Garcia F , Marques B , Lopez-Teijon M 
Published: June 2022

Abstract

Study question
Does hyaluronidase concentration used during denudation affect any success rate parameter?

Summary answer
There is an increase in the good quality blastocyst rates as well as an increment of maximum quality blastocysts when using less than 40 IU/ml.

What is known already
Denudation is a key process in IVF treatments. Combining chemical with mechanical forces allows the classification of mature and immature oocytes. Hyaluronidase dissolves the hyaluronic acid found between the cumulus cells aiding the denudation process. Time under exposure to this acid must be minimized in order to avoid potential harm to the oocytes.
Available commercial media report a concentration of 80 IU/ml. However, some laboratories have described benefits when diluting hyaluronidase even further. This statement makes sense when considering that damage to oocytes has been reported when incubating oocytes with hyaluronidase for too long.

Study design, size, duration
Prospective study designed to analyze the effect of different concentrations of hyaluronidase into egg donation treatments between August 2020 and November 2021. Time under the hyaluronidase solution was limited to a maximum of 30 seconds, after that denudation tips of decreasing diameter were used to complete the denudation process. We analyzed the percentage of mature oocytes, fecundation rates, good quality blastocyst rates, blastocyst quality and clinical success rates.

Participants/materials, setting, methods
This study includes 743 egg donation treatments cultured in a time-lapse incubator. In the control group (CG = 277 tratments) we used a solution of 80 IU/ml of hyaluronidase, group 1 (G1=196 treatments) consisted of those denudations carried out using a solution 40 IU/ml, group 2 (G2=123 treatments) using 28.6 IU/ml of hyaluronidase, and group 3 (G3=147 tratments) using 20 IU/ml of hyaluronidase.

Main results and the role of chance
Both metafase II rates (CG = 79.99%; G1=78.95%; G2=76.72%; G3=76.74%; p = 0.648) and fertilization rates (GC = 74.50%; G1=73.84%; G2=74.03%; G3=72.24%; p = 0.667) were not affected by the different dilutions. Still, good quality blastocyst rates increased with lower concentrations of hyaluronidase (CG = 59.96%; G1=64.34%; G2=63.61%; G3=63.28%; p &lt; 0.01).
When considering clinical results, we did not see any differences between the implantation rates of the embryos resulting from these different denudation solutions (CG = 50.56%; G1=50.00%; G2=44.74%; G3=47.95%; p = 0.92).
A deeper analysis into embryo quality allowed us to observe an incremented number of embryos with a top quality Inner Cell Mass (Gardner Score A) (CG = 59.56%; G1=62.70%; G2=69.50%; G3=66.46%; p &lt; 0.01), as well as an incremented number of embryos with a maximum quality trophectoderm (CG = 45.99%; G1=42.4%; G2=54.1%; G3=56.6; p &lt; 0.01).

Limitations, reasons for caution
Analyze the cumulative pregnancy rates for the different groups would be ideal to assess if the different hyaluronidase solutions affect the efficiency of in vitro fertilization treatments.

Wider implications of the findings
This results show an improvement in embryo quality when lower concentrations of hyaluronidase are used. This allows both to increase the treatment efficiency as well as to reduce the economic impact of these.

Trial registration number
Not applicable