Intracytoplasmic morphologically selected sperm injection or intracytoplasmic sperm injection: where are we 12 years later?

Twelve years ago, the introduction of motile sperm organelle morphology examination led to the development of a modified intracytoplasmic sperm injection procedure called intracytoplasmic morphologically selected sperm injection (IMSI) in which a spermatozoon selected under high magnification instead of 400× magnification is injected into an oocyte. Several studies found no correlation between IMSI and early embryo development in terms of fertilization while others found an increase in the fertilization rate. Conflicting results regarding the rates of implantation, pregnancy and abortion were also reported. A significant increase in the rate of top-quality embryos on days 3 and 5 was reported by the majority of the studies, and few failed to demonstrate a relationship between IMSI and embryo quality. Because of the extent of the population sizes and the diverse approaches and motile sperm organelle morphology examination classifications used by the studies reported thus far, definite conclusions on the co...