Defects in sperm fuction
The main investigation performed for male infertility is semen analysis.
It looks mainly at three parameters – sperm count, motility and normal forms. The values that are considered normal are as follows:
These parameters were decided based on semen analysis of fertile men (defined as men with partners who conceived within 12 months of stopping contraception). They were introduced as a guide to compare fertility.
Men, whose semen parameters falls short of these are not necessarily infertile and on the other hand, normal parameters do not guarantee fertility.
A routine semen analysis does not provide any evidence on sperm function. Sperm function depends on various factors like general health, smoking, alcohol, use of recreational drugs, environmental and occupational exposure.
There are various sperm function tests like hamster egg–human sperm penetration assay, hemizona assay, intact-zona sperm binding test. These are not available routinely as they are technically demanding and time-consuming.
Other tests like DNA fragmentation test are becoming more available.