Borderline form of empty follicle syndrome: is it really an entity?

We report two patients who were administered erroneously 1000 IU HCG instead of 10,000 IU for ovulation triggering in an assisted reproductive technology (ART) cycle. In one case no oocyte was retrieved from eight mature follicles after several washing attempts and retrieval day serum beta-HCG level was 21 mIU/ml. As there was no follicle in the other ovary we did not try a rescue protocol. In the other case two immature and one mature oocytes were retrieved from 15 mature follicles located in both ovaries. Retrieval day serum beta-HCG level was 12 mIU/ml. ICSI was performed in one mature and two in vitro maturated oocytes and the embryo transfer that was done 72 h after the retrieval yielded a healthy singleton pregnancy. Our experience shows that a borderline form of EFS may be an entity and it may be possible to see the formation of periovulatory events and even to obtain a pregnancy in an ART cycle where the ovulation was triggered by 1000 IU HCG.