Correlation of Lead Follicle Size on Day of Trigger with the Outcome of Invitro Fertilization (IVF) – A Retrospective Study


  • Blessy John
  • Mahalakshmi Saravanan
  • Lakshmanan Saravanan
  • Nidhi Sharma



In-vitro fertilization, lead follicle size, trigger


Introduction: IVF treatment involves the administration of supra-physiological doses of follicle stimulating hormone (FSH) to induce the growth of multiple ovarian follicles. Once ovarian follicles grow to an appropriate size, a trigger is administered to mature the oocytes in preparation for oocyte retrieval. However, no definite data exist to establish which follicle size on the day of trigger is most likely to yield a mature oocyte and successful IVF outcome. Knowledge of the size of follicles on day of trigger from which one could reasonably expect to retrieve a mature oocyte could enable the accurate determination of trigger efficacy. Therefore we sought to determine the size of the follicles on the day of trigger that would be most likely to yield a mature oocyte with increased blastocyst conversion rate after invitro fertilization thereby increasing the clinical pregnancy rate. 

Methodology: This retrospective study analysed 371 records of infertile women who underwent In-vitro fertilization in ARC International Fertility Center, Saveetha Medical College and Hospital, Chennai from March 2017 to March 2019. 

Results: In our study, highest ooctye maturation was observed when trigger was given when the lead follicle size was 22.1 to 24mm. a larger number of transferable good quality embryos are harvested from the group with lead follicle size of 22.1to 24mm (74 %). The 18 to 20mm group had 21% and 20.1 to 22mm group had 40%. The more than 24mm group had 50 % of good embryos. Finally in this study we did not have a statistically significant increase in the clinical viable pregnancy rate among the four groups. Though not statistically significant, we observed a slight increase in the clinical viable pregnancy rate among 22.1 to 24mm group 79% compared to other groups. 

Conclusion: In this study we observed that an early trigger(less than 22mm lead follicle size) or a very late trigger (>24mm) decreased the oocyte maturation rate thereby reducing the blastocyst conversion rate and clinical pregnancy rate. In this study we observed the ideal size of the lead follicle at the time of triggerto be 22 to 24 mm.


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