3 Discussion
The definition of a premature LH surge differs depending on the study. In our case, if the definition of Kummer et al.5 (LH levels ≥ 10 mIU/mL and > 50% rise from baseline) was used, an accurate premature LH surge or ovulation could not be predicted or specified. Therefore, the spontaneous ovulation date of our case was estimated from two parameters, the GS and crown-rump length (CRL). If a 10-mm GS is detected at 11 days after the OPU and that day is defined as a menstrual age of 40 days6, the estimated ovulation date is CD 9. The CRL was 15 mm 28 days after the OPU, and the estimated gestational age was 7 weeks+4, 8 weeks+2, and 9 weeks by 5, 50, and 95 percentile, respectively. Therefore, the estimated ovulation date was CD 8 (3–13)6. Because the natural menstrual cycle in our case was 28 days, this suggested that ovulation might have occurred earlier than it should have in a natural cycle.
If normal COS is in progress, early luteinization and follicular atresia will occur after a premature LH surge7. However, in our case, fertilization and implantation occurred after the presumed spontaneous ovulation day, and follicular development was observed after this time. A total of 31 oocytes were retrieved by using a GnRH agonist trigger.
A previous study reported that the outcome of luteal phase ovarian stimulation (LU) was higher than that for follicular phase ovarian stimulation (FO) regarding the total dosage of hMG, M2 rate7, number of oocytes collected, fertilization rate, and the number of day 3 embryos8. Additionally, a study that compared FO only to FO + LU reported that the FO + LU group had a higher number of retrieved oocytes, M2 rate, and 2 PN rate9. Theoretically, continued stimulation after spontaneous ovulation is therefore possible for retrieving oocytes.
Although good results are obtained with LU, in this case, as a result of ICSI performed on 21 M2 oocytes in our case, 12 of 21 had 2 PN, but 5 had 3 PN. Higher peak estradiol levels, large oocyte yields, a high gonadotropin dose, and a lengthy stimulation procedure are considered to increase 3 PN10,11. Therefore, additional attention should be paid to stimulation after spontaneous ovulation.