Table 2.

Oocyte literature score of individual abnormalities

	Studies analyzed	Studies with negative correlation on IVF outcome (value = 1)	Studies with no correlation on IVF outcome (value = 0)	Studies with positive correlation on IVF outcome (value =  − 1)	OLS
Extracytoplasmatic abnormalities
Cumulus-oocyte complex	6	5	1	0	8.33
Zona pellucida	17	10	6	1	5.29
Perivitelline space	12	6	6	0	5.00
Polar body	10	5	4	1	4.00
Shape	9	3	6	0	3.33
Giant	3	0	3	0	N.A
Intracytoplasmic abnormalities
Vacuolization	14	10	4	0	7.14
Refractile bodies	4	2	2	0	5.00
Ser cluster	9	7	2	0	7.78
Granularity	8	5	3	0	6.25
Color variation	6	2	4	0	3.33
Cumulative abnormalities	10	6	4	0	6.00

OPS, oocyte predictive score; N.A., not applicable