Influence of blood clots in the cumulus complex on oocyte fertilization and cleavage.

Since multiple ovarian punctures are performed during oocyte retrieval, the likelihood of blood contaminating the follicular fluid is high. The purpose of this study was to determine whether the presence of blood clots, which are frequently seen in the cumulus of oocytes retrieved under ultrasound guidance, has any effect on fertilization and subsequent embryo cleavage and to identify oocyte characteristics which may predict these events. Oocytes were morphologically graded and the presence of blood clots in the cumulus was recorded. Cases in which the male partner had a total motile sperm count less than 20 x 10(6) on the day of insemination were excluded from the logistic regression analysis. The presence of blood clots in the cumulus was a negative predictor of cleavage [odds ratio (OR) = 0.54]. The results indicate that an oocyte with optimal quality is one which is spherical (OR = 5.45), has an expanded corona (OR = 3.80) and has no blood clots in the cumulus complex.