During IVF with inctracytoplasmic sperm injection (ICSI) the selection of the single sperm that will be injected in the oocyte, is based on its morphology and motility. Studies have shown that the presence of morphological abnormalities in the sperm is associated with reduced fertility, low pregnancy rates and high risk of miscarriage.
The microscope magnification that is used during ICSI is around 200x or 400. This is not sufficient to detect anomalies that are mainly found in the sperm head, like vacuoles. A new technique has been developed recently that allows the detection of those abomalies and a better and more thorough examination of the single sperm that will be chosed with the fertilisation of the oocyte. This technique is called intra-cytoplasmic morphologically selected sperm injection (IMSI) and the magnification that is used for the selection is 6000x.
Studies have shown than IMSI improves the pregnancy rates in couples with oligoasthenoteratospermia  and those with maternal age over 37 years . Morever, Cassuto et al have shown that IMSI reduced significantly the presence of major birth defects when compared to ICSI, in a study performed on over 1000 babies .
- Kim H.J., Yoon H.J., Jang J.M., Oh H.S., Lee Y.J., Lee W.D., Yoon S.H., Lim J.H. 2014. Comparison between intracytoplasmic sperm injection and intracytoplasmic morphologically selected sperm injection in oligo-asthenoteratospermia patients. Clin Exp Reprod Med. 41: 9-14.
- Setti A.S., Figueira R.C.S., Braga D.P.A.F., Aoki T., Iaconelli Jr A., Borges Jr E. 2013. Intracytoplasmic morphologically selected sperm injection is beneficial in cases of advanced maternal age: a prospective randomized study. Eur J Obstet Gynecol Reprod Biol. 171: 286-290.
- Cassuto N.G., Hazout A., Bouret D., Balet R., Larue L., Benifla J.L., Viot G. 2014. Low birth defects by deselecting abnormal spermatozoa before ICSI. Reprod Biomed Online. 28:47-53.