P–690 Clinical predictors of a high oocyte maturation rate in IVF treatment cycles
Authors: Garratt J , Raikundalia B , Rimington M , Ahuja K , Macklon N , Linara-Demakakou E 
Published: August 2021

Abstract

Study question
Which clinical parameters predict a high oocyte maturation rate in patients undergoing IVF treatment?

Summary answer
Time between oocyte collection and insemination demonstrated significant association with oocyte maturation and represents a parameter that could be optimised in IVF cycles.

What is known already
Oocyte maturation is an important factor determining IVF outcomes and can be a rate-limiting step for patients undergoing treatment. A number of clinical and laboratory variables may affect this process, including the choice of trigger prior to oocyte collection, and certain laboratory procedures. Identification of which of these are predictors of maturation in individual centres enables local protocols to be optimised.

Study design, size, duration
This is a retrospective study of 714 oocyte collections from 661 women between January 2020 to November 2020 treated in a large, single centre in the UK. Subsequent fertilisation on fresh oocytes consisted of 371 IVF and 343 ICSI cycles.

Participants/materials, setting, methods
Patient and treatment data was collected by clinical staff at time of treatment. Either GnRH agonist, hCG or double trigger were administered 36 hours before collection. Prior to ICSI, oocyte maturation was assessed by visualisation of polar body (PB) extrusion. After IVF, the number of 2PNs plus unfertilised oocytes with PB extrusion were assessed. Univariate analyses consisted of Mann-Whitney test, t-test, Fisher’s Exact test or ANOVA. Potential predictors were investigated by logistic regression.

Main results and the role of chance
The end point was maturation rate, defined as high (greater or equal to 70%) or low (less than 70%). Factors predictive of a high rate included insemination more than 4 hours after collection. Oocytes inseminated over 4 hours post-collection displayed significantly higher maturation rates than oocytes inseminated less than 2 hours after collection (69% and 61% respectively; P = 0.01). Oocytes inseminated between 2–4 hours also had higher maturation than those inseminated less than 2 hours post-collection, but this did not reach significance (67% and 61%, respectively; P = 0.06). Further, oocytes fertilised by ICSI had significantly higher maturation than conventional IVF (77% and 67%, respectively, P &lt; 0.001). No significant difference in oocyte maturation between triggers was observed. Similarly, neither age, AMH, a diagnosis of PCOS or number of oocytes collected predicted oocyte maturation in univariate analysis. Logistic regression analysis showed only time between oocyte collection and insemination (aOR 2.12; 95% CI 1.03–4.38; P = 0.04) to be a significant independent predictor.

Limitations, reasons for caution
Varying means of data collection across clinics and between clinical staff inevitably leads to provision of incomplete data and should be taken into consideration alongside interpretation. Prescription bias of specific triggers to certain patient demographics should be noted.
Wider implications of the findings: Collectively, these results suggest that greater time between oocyte collection and insemination could be recommended to IVF clinics that wish to optimise their oocyte maturation. Triggering final maturation with GnRH agonist versus hCG or dual trigger did not have a significant effect on oocyte maturation when adjusted for confounders.

Trial registration number
Not applicable