A method of operating an ultrasound diagnosis apparatus includes: obtaining a three-dimensional (3D) ultrasound image including an ovarian region； detecting, based on at least one parameter used for extracting a particular oocyte, a plurality of candidate ovarian follicles from which mature oocytes are more likely to be extracted in the 3D ultrasound image； registering a two-dimensional (2D) ultrasound image corresponding to a first cross-section of the ovarian region to the 3D ultrasound image； and guiding, based on a result of the registering, a position of at least one candidate ovarian follicle from which an oocyte is to be extracted in the 2D ultrasound image.
