Prematurely ruptured dominant follicles often retain competent oocytes in infertile women

Abstract

Ovulation consists of a follicle’s rupture and subsequent oocyte extrusion, although there is a paucity of evidence regarding whether every follicle’s rupture is associated with extrusion of its oocyte. We examined this issue in a large-scale window-of-opportunity study by attempting aspiration of single dominant follicles that were found to have ruptured before a scheduled oocyte retrieval during in vitro fertilisation and embryo transfer treatment of infertile women. We were able to aspirate 587 of 1,071 ultrasonographically confirmed post-rupture dominant follicles from 1,071 women (i.e. one dominant follicle per woman) and retrieved 225 oocytes (oocyte recovery ratio: 43.4% of aspirated follicles), which yielded 28 live births (live birth ratio: 11.0% of retrieved oocytes). Interestingly, the live birth ratio for post-rupture dominant follicles was not statistically different from that achieved using regular pre-rupture aspiration of dominant follicles (1,085/8,977, 12.1%). These findings suggest that oocyte extrusion frequently does not occur after follicle rupture in infertile women undergoing in vitro fertilisation treatment, although the oocyte retained in the follicle can remain competent for use during that treatment.