Oocyte morphology predicts outcome of intracytoplasmic sperm injection

To examine the influence of cytoplasmic morphology on the success rate ofintracytoplasmic sperm injection (ICSI), the morphology of 837 metaphase IIoocytes was assessed after cumulus stripping. The main abnormalitiesdetected were excessive granularity, cytoplasmic inclusions such asvacuoles, smooth endoplasmic reticulum clustering and refractile bodies.Microinjection was performed in 538 oocytes with normal cytoplasm, 142 outof 161 with excessive granularity and 112 out of 138 with cytoplasmicinclusions. Very poor oocytes were not injected. No difference was found infertilization rate. The embryos achieved cleaved normally and a similarnumber of good quality embryos among the three groups was noted. Theoutcome of transfer of embryos derived solely from normal oocytes (group A:72 patients, 183 embryos) was compared with those from oocytes withcytoplasmic abnormalities (group B: 34 patients, 85 embryos). In group A,17 clinical pregnancies (24% per patient, implantation rate 10%) wereestablished. In group B, only one clinical pregnancy (3% per patient,implantation rate 1%) was established, from the transfer of embryos derivedfrom oocytes with homogeneous granularity of the cytoplasm. No pregnancyresulted following the transfer of embryos from eggs with cytoplasmicinclusions. The difference was statistically significant. The outcome ofICSI is dependent on the quality of the oocytes retrieved. Normalfertilization and early embryo development were achieved in oocytes withabnormal cytoplasm morphology, but the resulting embryos failed todemonstrate the same implantation potential as those derived from oocyteswith normal cytoplasm.