IMSI, or Intracytoplasmic morphologically selected sperm injection, is a technique that became popular over a decade ago. It uses a very high-power microscope to examine and select the sperm that will then be introduced in the egg with the aim of increasing the possibilities of a successful implantation and reducing the probabilities of miscarriage.
However, two extensive and recent reviews of IMSI have not demonstrated an improvement in the parameters of fertilization, embryo development, implantation rate or miscarriage rate and they conclude that, to date, there is insufficient medical evidence to support its routine use and that more and better-quality studies are necessary before the use of IMSI is recommended in clinical practice. The technique would appear to be important as a method for the study of sperm morphology, but not as a strategy to be proposed to patients, leading them to believe that they will have a better prognosis.
Standard selection of sperm prior to intracytoplasmic sperm microinjection (ICSI) is still the strategy to be used in clinical practice, since others – especially IMSI – are not backed by adequate studies.