Prediction of oocyte maturity before denudation: Is the assessment of COC morphology a reliable option?

Objective: We aimed to demonstrate the predictive value of morphological assessment of cumulus-oocyte complexes (COCs) prior to denudation in distinguishing mature and immature oocytes.

Materials and methods: The study consisted of two stages. Five embriologists were enrolled to the first stage of the study and they divided COCs into two groups according to the morphologic features of the COS's: COCs with mature oocytes and COCs with immature oocytes. The process was overseen by one embryologist. Two hours later, COCs were denuded, and the maturity of oocytes was evaluated by another embryologist. The results were recorded. The first stage was terminated when each embryologist had evaluated a minimum of 100 COCs. In the second stage, three embryologists applied the procedure continuously for one more month. At the end of the study, the effects of continuous assessment on the prediction success were evaluated.

Results: Eighty patients were enrolled in the study, and a total of 1039 COCs were examined. In the first stage of the study, 69% of immature and 80% of mature oocytes were identified correctly by the embryologists. There was no significant difference among the embryologists in terms of success rates. In the second stage of the study, the success rates of immature oocyte prediction increased for all three embryologists. However, a statistically significant increase was observed for only one embryologist (p<0.05). However, the prediction rates of mature oocytes were comparable with the results of the first stage of the study. There was no significant relationship between the number of COCs and the prediction value.

Conclusion: Morphological assessment of COCs before denudation does not provide accurate results in identifying mature and immature oocytes.