The incidence of genuine empty follicle syndrome

Abstract

OBJECTIVE: Rarely, no oocytes are retrieved from mature ovarian follicles after ovarian stimulation because of a condition known as empty follicle syndrome (EFS). EFS can be divided into two types: 1) false EFS where hCG is not administered properly; or 2) genuine EFS, a failure to retrieve oocytes despite optimal levels of β-hCG. The incidence and etiology of genuine EFS is unknown. The aim of this study was to determine the incidence of genuine EFS in a large cohort of patients and describe the clinical characteristics of these patients. DESIGN: Retrospective study. MATERIALS AND METHODS: All ART cycles at a single fertility center from year 2004 to 2009 comprised the study cohort, a total of 12,359 patients and 18,294 oocyte retrieval procedures. In order to exclude cases where an absence of oocytes was due to a poor response to stimulation or technical issues, only cases with 5 or more follicles with a diameter of at least 14mm on the day of hCG administration were included. Serum β-hCG levels were measured in cases where no oocytes were retrieved. RESULTS: A total of 46 cases of EFS were identified, representing an incidence of 0.25%. Only 2 patients had elevated serum β-hCG on the day of oocyte retrieval (124 and 61 mIU/mL). Both patients had primary infertility, with male factor as etiology for one patient, and PCOS for the other. Both patients had normal ovarian reserve. Neither patient used anti-inflammatory medications during stimulation. Both patients underwent 11 days of ovarian stimulation, with gonadotropin usage of 6225 and 674 IU, resulting in peak serum estradiol levels of 1730 and 2340 pg/ml, respectively. Neither patient underwent a subsequent ART cycle. No recurrent case was identified. The incidence of genuine EFS was 0.016% in this cohort. CONCLUSION: In this cohort of 12,359 patients, genuine EFS was very rare, and most cases were due to a failure to administer hCG. The etiology of genuine EFS warrants further investigation.