Authors: David Hill, PhD, Man Li, PhD, Catherine Marin, MD, Hal Danzer,MD, Mark Surrey, MD
Objective: Embryo biopsy methods, particularly mechanical partial zona dissection (PZD) and acidified Tyrode’s solution (ATS) have been compared by several authors. These two methods are both believed to be similarly efficient and safe in experienced hands. We believe that the “embryo biopsy medium” (EBM) used in this step is just as important as the method employed for zona opening, and its effect on the embryo may be easily overlooked. This retrospective data analysis study compared the pregnancy rate using two kinds of EBM used at our center from 03/01/2002 to 10/31/2003 for aneuploidy screening cases using Fluorescent in Situ Hybridization (FISH).
Materials and methods: Sequential media G1, G2 (Vitrolife, Sweden) and a triple gas (5%O2, 6%CO2, balance nitrogen) incubator internal environment were used for embryo culture. Biopsy medium 1(EBM1) was Hank’s Balanced Salt Solution without Ca++ & Mg++ (HBSS, Sigma H6648) supplemented with 5% Synthetic Serum Supplement (Irvine Scientific) and 0.05M Sucrose. Medium 2(EBM2) was similar to EBM1 but was supplemented with alanyl-glutamine, EDTA, sodium pyruvate and sodium lactate (DL). A total of 165 cases of PZD embryo biopsy for aneuploidy screening were done during 03/01/02 to 03/31/03 in EBM1 (group 1). At the same time, 744 age-matched, non-biopsy cases were used as controls for group 1. From 04/01/03 to 10/31/03, another 146 ATS biopsy cases were done in EBM2 (group 2), and in the same period 280 non-biopsy cases served as controls for the group 2 cases.
Conclusion: Micromanipulation medium for embryo biopsy, and possibly for all micromanipulative procedures, may be as important as the embryo culture medium itself in its effects on embryonic growth and further development. Development of biopsied embryos was significantly impaired if the embryos were exposed even briefly in medium lacking amino acids and its necessary nutrients, such as sodium pyruvate and sodium lactate (DL). Supplementation with SSS can not compensate for the depletions, even when the embryos were subsequently cultured in the presence of amino acids and nutrient rich medium, such as G2 medium. We believe this step–that of using embryo biopsy