Embryo "Glue" - Does it work?
The study included a review all of the published randomized controlled trials (RCTs) in which the adherence compound utilized was a hyaluronic acid. They compared patients whose transfer media contained no or very low concentrations of hyaluronic acid to those whose media contained functional concentrations of this compound. The study included 3898 women from 17 RCTs. The concentration of hyaluronic acid considered low was.125 mg/ml while the concentration considered functional was .5 mg/ml. The end points that were evaluated included live birth rate, clinical pregnancy rate, multiple pregnancy, and adverse events.
For simplicity in understanding the review, the data may be expressed as the outcome per 1000 events in each end point that was reviewed. The table below expresses these results.
No or Low Hyaluronic Acid High Hyaluronic Acid
Live Birth 374/1000 458/1000
Clinical Pregnancy 350/1000 428/1000
Multiple Pregnancy 20/1000 37/1000
Adverse events 63/1000 48/1000
This review suggests that there is moderate quality evidence of improved clinical and live birth rates when embryo transfer media contains hyaluronic acid at a concentration on .5 mg/ml. The authors suggest that the slight increase in multiple birth rate might be the result of the use of the adherence compound in conjunction with the transfer of more one embryo. The slight increase in adverse effects noted in the "high hyaluronic acid group" was not statistically significant.
This review article did not address any potential toxicity related to the addition of hyaluronic acid to the embryo transfer media. Adherence compounds offer yet another option in our IVF laboratories toward improving prospects for success. A long term study of children born following the use of these compounds in IVF culture media would provide important reassurance that these agents do not cause any harmful effects to the embryo.