Initial IVF-ET experience with assisted hatching performed 3 days after retrieval followed by day 5 embryo transfer

Objective: To report our initial IVF-ET experience combining assisted hatch ing performed 3 days after oocyte retrieval with day 5 embryo transfer (ET) . Design: Retrospective review of 110 consecutive IVF cycles not involving do nor oocytes, including 16 cycles that involved assisted hatching performed 3 days after oocyte retrieval in combination with day 5 ET. Setting: Academic teaching hospital IVF center. Patient(s): Eighty-six consecutive IVF patients undergoing ET. Intervention(s): Assisted hatching using acid Tyrode's solution performed 3 days after oocyte retrieval in selected cases in combination with day 3 or 5 ETs. Main Outcome Measure(s): Clinical pregnancy rate per ET. Result(s): Of the 16 women undergoing day 5 ET following day 3 assisted hat ching, 14 had a clinical pregnancy. These included 11 ongoing/delivered sin gletons and 2 ongoing/delivered twin pregnancies, neither of which was mono chorionic. These clinical and ongoing/delivered pregnancy rates compared ve ry favorably with those of 54% and 46%, respectively, for the 35 patients u ndergoing day 5 ETs without assisted hatching, even though the latter group appeared to be better IVF candidates based on the prognostic factors commo nly used to predict success. Conclusion(s): Our experience suggests that day 3 assisted hatching followe d by day 5 ET may be a useful combination in selected patients. Although no t seen in our small series, an increased risk: of monochorionic pregnancies remains a theoretical concern when such a combination is used, since both assisted hatching and blastocyst transfers have been independently linked t o an increased risk in some reports. (Fertil Steril (R) 2000; 74:668-71. (C ) 2000 by American Society for Reproductive Medicine.).