AIM: The follicular size has been considered for years as an index for oocyte maturity in stimulated ovulation cycles so that the time of initiating human chorionic gonadotropin (HCG) has been formerly determined by the ultrasonography measurement of larger follicles. The other studies have demonstrated that there was no significant difference between fertility of oocytes aspirated from follicles with various sizes. The objective of this study to explore the associations among the size and volume of extracted follicles at the time of oocyte collection with the rate of collection, oocyte maturity, and oocyte competence in the intracytoplasmic sperm injection (ICSI) therapeutic cycles. METHODS: This prospective study was performed on 412 stimulated ovulation cycles of 340 patients visiting the infertility center of Tehran Mirzakouchakkhan Hospital from September 2011 to February 2013, so that a total of 2324 follicles were investigated. The follicular diameter and fluid volume were measured then the follicles were classified into four groups regarding the aforesaid spatial dimensions. The association among the size and volume of follicles with the probability of oocytes collection, oocytes maturity, fertility competence, cleavage rate, and embryo quality was assessed. RESULTS: The majority of follicles (38%) were categorized in the group C with the follicle diameter of 16-20 mm and volume of 1-3 mm3. No significant difference was observed between these four follicle groups in terms of oocyte collection rate. There was a significant difference (P<0.05) between the group A (diameter>21 mm; volume>5 mm3) and group D (diameter<12 mm; volume≤1 mm3) regarding oocyte maturity and collection rate of metaphase II (MII) oocyte. Conversely, this difference was not significant between groups A, B (diameter=16-20 mm; volume=3-5 mm3), and C (diameter=12-15 mm; volume=1-3 mm3). The fertility rate of oocytes aspirated from small follicles was 55%, which is significantly lower than the fertility rate of oocytes obtained from follicles larger than 12 mm and volume of more than 1 mm3. However, the oocytes aspirated from smaller follicles continue to cleaved, and the quality of embryos did not significantly differ from that embryos cultivated from larger follicles. CONCLUSION: This study showed that the size of follicles and the oocytes maturity in stimulated ovaries are not considerably associated, thus might be independent factors. The development competence of oocytes from smaller follicles was similar to oocytes aspirated from larger follicles. Thus follicles smaller than 12 mm in size and 1 mm3 in volume should be also aspirated. Moreover, this study suggests initiating HCG at the phase with follicles equal to or larger than 16 mm to save time and expense for the patient.
AIM: The follicular size has been considered for years as an index for oocyte maturity in stimulated ovulation cycles so that the time of initiating human chorionic gonadotropin (HCG) has been formerly determined by the ultrasonography measurement of larger follicles. The other studies have demonstrated that there was no significant difference between fertility of oocytes aspirated from follicles with various sizes. The objective of this study to explore the associations among the size and volume of extracted follicles at the time of oocyte collection with the rate of collection, oocyte maturity, and oocyte competence in the intracytoplasmic sperm injection (ICSI) therapeutic cycles. METHODS: This prospective study was performed on 412 stimulated ovulation cycles of 340 patients visiting the infertility center of Tehran Mirzakouchakkhan Hospital from September 2011 to February 2013, so that a total of 2324 follicles were investigated. The follicular diameter and fluid volume were measured then the follicles were classified into four groups regarding the aforesaid spatial dimensions. The association among the size and volume of follicles with the probability of oocytes collection, oocytes maturity, fertility competence, cleavage rate, and embryo quality was assessed. RESULTS: The majority of follicles (38%) were categorized in the group C with the follicle diameter of 16-20 mm and volume of 1-3 mm3. No significant difference was observed between these four follicle groups in terms of oocyte collection rate. There was a significant difference (P<0.05) between the group A (diameter>21 mm; volume>5 mm3) and group D (diameter<12 mm; volume≤1 mm3) regarding oocyte maturity and collection rate of metaphase II (MII) oocyte. Conversely, this difference was not significant between groups A, B (diameter=16-20 mm; volume=3-5 mm3), and C (diameter=12-15 mm; volume=1-3 mm3). The fertility rate of oocytes aspirated from small follicles was 55%, which is significantly lower than the fertility rate of oocytes obtained from follicles larger than 12 mm and volume of more than 1 mm3. However, the oocytes aspirated from smaller follicles continue to cleaved, and the quality of embryos did not significantly differ from that embryos cultivated from larger follicles. CONCLUSION: This study showed that the size of follicles and the oocytes maturity in stimulated ovaries are not considerably associated, thus might be independent factors. The development competence of oocytes from smaller follicles was similar to oocytes aspirated from larger follicles. Thus follicles smaller than 12 mm in size and 1 mm3 in volume should be also aspirated. Moreover, this study suggests initiating HCG at the phase with follicles equal to or larger than 16 mm to save time and expense for the patient.