The association between follicle size and oocyte development as a function of final follicular maturation triggering.

RESEARCH QUESTION: To study the association between follicle size and oocyte/embryo quality, as a function of different triggering modes for final follicular maturation. STUDY DESIGN: Cohort study conducted in a single tertiary medical centre between July 2018 and May 2019. All women undergoing ovarian stimulation with triggering using human chorionic gonadotrophin (HCG), gonadotrophin-releasing hormone (GnRH) agonist or dual trigger (GnRHa + HCG) were included. Before ultrasound-guided follicular aspiration, follicles were measured and divided into three groups according to maximum dimensions: large ≥16 mm, medium 13-15 mm and small <13 mm. Microscopic examination of the follicular aspirates was performed by an embryologist. Each follicle aspirated was evaluated for oocyte maturation, oocyte fertilization and embryo quality. RESULTS: A total of 640 follicles were measured, including 402 (62.8%) in the large, 148 (23.1%) in the medium and 90 (14.1%) in the small groups. Oocytes were obtained during aspiration from 76.3%, 70.3% and 55.6% of the large, medium and small follicle groups, respectively (P = 0.001). The mature oocyte (metaphase II) rate was significantly higher in the large (P = 0.001) and medium (P = 0.01) compared with the small follicle group. Nevertheless, no between-group differences were observed in fertilization or top quality embryo rates among mature oocytes regardless of the size of the follicle from which they originated. Triggering mode did not influence oocyte recovery rate in the different follicle size groups. CONCLUSION: A higher oocyte recovery rate was observed from follicles >13 mm, however, mature oocytes achieved similar fertilization and top quality embryo rates regardless of follicle size. Triggering mode did not influence oocyte recovery rate.

Does a Large (>24 mm) Follicle Yield a Competent Oocyte/Embryo?

AIM: To evaluate the effect of large follicular size (≥24 mm) at day of oocyte retrieval on oocyte/embryo quality. PATIENTS AND METHODS: A cohort study was conducted in a single tertiary medical center between July 2018 and May 2019. Before ultrasound-guided follicular aspiration, follicles were measured and divided into 2 groups according to their maximal dimensional size: large: ≥24 mm and normal: <24 mm. Microscopic examination of the follicular aspirates was performed by an embryologist. Each follicle aspirated was evaluated for oocyte maturation, oocyte fertilization, and embryo quality. RESULTS: 428 follicles were measured, including 383 (62.81%) in the normal and 45 (14.06%) in the large follicle groups. Oocytes were achieved during aspiration from 297 (75.5%) and 29 (64.4%) of the normal and large follicle groups, respectively (p = 0.05). No in-between group differences were observed in mature oocyte (MII), fertilization, and top-quality embryo (TQE) rates. Nevertheless, once a zygote (2PN) was achieved, a trend toward a higher TQE rate/2PN was found in the large follicle group (16/19 [84.2%] vs. 115/171 [67.3%]; p = 0.062). CONCLUSION: While a nonsignificant decrease in oocyte recovery rate was found in follicles ≥24 mm, the zygote and TQE per follicle were comparable.

Do Follicles of Obese Patients Yield Competent Oocytes/Embryos?

AIM: This study evaluated the competency of oocytes/embryos derived from follicles >15 mm in diameter from obese patients, compared with nonobese patients. PATIENTS AND METHODS: A cohort study was conducted in a single tertiary medical center between July 2018 and May 2019. Before ultrasound-guided follicular aspiration, follicles were measured and those with maximal dimensional size >15 mm were tracked. Microscopic examination of the follicular aspirates was performed by an embryologist. Each follicle aspirated was evaluated for oocyte maturation, oocyte fertilization, and embryo quality. RESULTS: 457 follicles were measured: 380 (83.2%) in nonobese and 77 (16.8%) in obese patients. No in-between group differences were observed in the causes of infertility, patients' demographics, or ovarian stimulation characteristics. Oocytes were achieved during aspiration from 277 (72.8%) and 54 (70.0%) of the nonobese and obese groups, respectively (p = 0.67). No in-between group differences were observed in fertilization (2PN/oocyte), top quality embryo (TQE) per zygote (2PN), and TQE per follicle. CONCLUSION: Oocyte recovery rate from follicles >15 mm is unrelated to patients' BMI. Moreover, the oocytes recovered from obese patients are competent yielding comparable zygote and TQE per follicle/oocyte, compared with nonobese patients. Further investigation is required to strengthen this finding.