Evidence of 'genuine empty follicles' in follicular aspirate: a case report

Failure to retrieve oocytes after normal ovarian stimulation has been labeled 'empty follicle syndrome' (EFS). The existence of genuine EFS has been questioned and is still controversial. Here, we report an unusual case in which an extraordinary number of empty follicle-like structures were identified in the ovarian aspirate at the time of retrieval. A 31-year-old woman presented with a 4-year history of primary infertility and underwent ovulation induction. The patient was given hCG and oocyte retrieval was performed 36 h later. During the oocyte retrieval, more than 200 tiny structures resembling pre-antral follicles were noted in the ovarian aspirate. They exhibited two to three layers of granulosa cells and appeared to enclose an immature oocyte. They showed a great variation in size ranging between 40 and 80 microm. These structures were further characterized by electron microscopy and cultivated in vitro to assess hormone secretion. The follicles were found to be devoid of oocytes, but each had a readily identifiable zona. Hormone assays revealed that these follicles were secreting increasing levels of estradiol. A second in vitro fertilization attempt gave similar results. These data are suggestive of some failure in the oocyte maturation process. We speculate that this may be the first actual evidence to support the existence of true empty follicles, which if left to grow in vivo might lead to empty graffian follicles and genuine EFS.