Intracytoplasmic morphologic sperm injection

IMSI, intracytoplasmic injection of morphologically selected spermatozoa, is a Level II technique used in in vitro fertilisation. It takes the form of a variant of traditional ICSI, both of which consist of the direct injection of a spermatozoon inside the cytoplasm of the oocyte. ICSI is a procedure that has become the treatment of choice for a large number of patients, not only those with seminal fluid abnormalities. Since the introduction of ICSI, the focus has always been on the importance of assessing the morphology of the male gametes. It is essential to select a mobile spermatozoon of good quality in order to obtain better embryo quality. Indeed, several studies have shown how sperm morphology affects fertilisation, embryo quality and pregnancy outcomes in in vitro fertilisation. Since the 2000s, advanced sperm selection techniques have been developed based on the accurate assessment of sperm morphological abnormalities. These techniques allow the intracytoplasmic injection of morphologically selected spermatozoa (IMSI) by basing selection on sperm morphology, surface charge, apoptosis, birefringence and visualisation of head vacuoles. IMSI is an innovative, non-invasive technique that is therefore a variant of ICSI, based on the use of microscopes equipped with high-powered 6000X magnification lenses (as opposed to those normally used for the traditional ICSI technique, which have 200/400X magnification power) that allow the biologist specialist to assess spermatozoa in greater detail, enabling their selection. In cases of severe oligozoospermia, when ICSI seems to be the couple's only option, or even in cases of unexplained infertility or repeated failures of standard in vitro fertilisation techniques, the accurate selection of spermatozoa could enhance the success of the assisted reproduction technique. Indeed, recent studies seem to show that in couples with repeated IVF/ICSI failures, the IMSI technique significantly improves pregnancy outcome, with a tendency towards better embryo quality. This technique allows the selection of better quality gametes with apparently higher success rates in terms of implantation rate, clinical pregnancy rate and especially delivery rate. The improvement in embryo quality through sperm selection could have a positive effect on achieving assisted reproduction goals even in cases of oligospermia alone. Comforting results are also suggested in terms of reducing the number of miscarriages, compared with traditional techniques. Finally, based on current knowledge, no prenatal or postnatal complications have been reported in mothers and offspring following the IMSI procedure.¹²³⁴. Currently, however, there is no clear evidence of the advantages of the IMSI technique as there is still limited and sometimes contradictory data; this technique is therefore not used routinely, but only after careful evaluation by the referring specialist who assesses the case of the individual couple.

Bibliography

1. Can intra cytoplasmatic morphologically selected sperm injection (IMSI) technique improve outcome in patients with repeated IVF-ICSI failure? a comparative study (Einat Shalom-Paz ¹, Saja Anabusi, Medeia Michaeli, Etti Karchovsky-Shoshan, Nechami Rothfarb, Tal Shavit, Adrian Ellenbogen). ecol Endocrinol 2015 Mar;31(3):247-51.

2. The IMSI Procedure Improves Laboratory and Clinical Outcomes Without Compromising the Aneuploidy Rate When Compared to the Classical ICSI Procedure. Daniel Luna,¹ Roly Hilario,² Julio Dueñas-Chacón,² Rocío Romero,² Patricia Zavala,²Lucy Villegas,¹ and  Javier García-Ferreyra^1.Clin Med Insights Reprod Health 2015 Nov 12;9:29-37. 5
3. The Beneficial Role of Intra Cytoplasmic Morphologically Selected Sperm Injection (IMSI) in Assisted Reproduction Esmat Mangoli ¹, Mohammad Ali Khalili ¹ . od Infertil. 2020 Jan-Mar;21(1):3-10.
4. Can intracytoplasmic Morphologically Selected Spermatozoa Injection be Used as First Choice of Treatment for Severe Male Factor Infertility Patients? Geeta Goswami ¹, Meeta Sharma ¹, Deepika Jugga ¹, Devi M Gouri ¹m Reprod Sci 2018 Jan-Mar;11(1):40-44.

Figure 1. Example of spermatozoa visualisation under light microscopy with magnification powers of 200x, 400x, 900x (magnifications usually used in ICSI practice).
Figure 2. Example of spermatozoa visualisation in light microscopy with lenses at 6000x magnification power (magnification used in IMSI practice). Increasing the power increases the quality of visualisation of details.