 Coculture can be an effective treatment for patients who have failed previous IVF cycles or who have poor embryo quality.A study of 12,377 embryo cultures showed that endometrial coculture is significantly better than sequential culture media; the rates (fraction) reaching blastocyst stage were 56% versus 46% in the coculture versus the sequential system, respectively, with own oocytes.With eggs from ovum donations, the rates were 71% versus 56%, respectively.