Stephen Harbottle Lead Embryologist, Cambridge IVF, UK
One aspect of male infertility which can be assessed is the level of abnormalities present in the sperm. Such abnormalities result in poorer quality sperm which in turn reduce the possibility of fertilisation of an egg.
They have also been shown to affect the genetic makeup of an embryo which in turn could lead to miscarriage.
Many sperm abnormalities can be identified by the embryologist using a normal microscope with magnification 400-600x. This is used when ICSI treatment is performed.
However, by looking at sperm using much higher magnifications (up to x6000) coupled with a digital imaging system, it has recently become possible to identify structures within the sperm head, known as vacuoles which can seldom be seen with a normal microscope.
The presence of these sperm head vacuoles relates to decreased and abnormal blastocyst and embryo development.
Selecting sperm using IMSI can help to reduce the possibility of injecting a sperm with damaged DNA into the egg.
Recent research has shown that for certain groups of patients sperm selection using IMSI is associated with better embryo quality, higher pregnancy and lower miscarriage rates (Antinori et al, 2008).
IMSI may be useful for the following patient groups:
• Male partners over 40 years
• Patients for whom the semen analysis has identified a high number of abnormally formed sperm
• Patients that have not achieved good quality embryos in previous cycles (if not related to egg quality)
• Patients with previously unsuccessful treatment cycles (if not related to egg quality)
• Patients with a history of miscarriages