About 13% of women may have the wrong method of oocyte insemination when undergoing in vitro fertilization by failure to evaluate the abnormal hypo-osmotic swelling test score.

Purpose: To determine the percentage of males with a low hypoosmotic swelling (HOS) test score in couples having in vitro fertilization-embryo transfer (IVF-ET) where the male partner had normal motile densities and no antisperm antibodies.

Methods: The results were also analyzed according to the percentage of HOS scores < 50% when morphology using strict criteria was < or = 4% or > 4%. A retrospective review was performed.

Results: There were 250 subnormal HOS scores out of 1993 otherwise normal semen specimens.

Conclusions: 12.5% of couples would have had conventional oocyte inseminations rather than ICSI if the HOS test had not been not performed (it is rarely performed by other IVF centers). Without ICSI expected live delivered pregnancy rates would be close to zero for males with low HOS tests < 50%. Intracytoplasmic sperm injection allows pregnancy rates almost as good as completely normal sperm.