The value of semen characteristics and tests of sperm function in selecting couples for intra-uterine insemination.

In order to improve the selection of couples for intrauterine insemination (IUI) because of longstanding primary infertility of alleged male origin, we have performed a prospective study measuring conventional and advanced analysis of sperm characteristics, the hypoosmotic swelling test, the Shorr stain, the acidified aniline blue stain and alpha-glucosidase activity in seminal plasma, of 89 couples with no demonstrable abnormality of the female partner. Twenty-four couples attained spontaneous conception, 23 were successful within six cycles of IUI, and 42 remained without conception in spite of IUI during six unstimulated cycles. The proportion and concentration of spermatozoa with progressive motility was significantly lower (P < 0.01) in the successful IUI cases than in the couples attaining spontaneous conception, and the lower quartile value was lower in the former than in the latter. There were less pregnancies among IUI treated couples when sperm concentration and motility were within the range of normal fertile men, or when the concentration of white blood cells was elevated. More pregnancies occurred when markers of epididymal function, namely the result of the Shorr stain and alpha-glucosidase measurement, were normal. Total progressive motility and the result of the Shorr stain were the only independent variables selected by logistic regression to discriminate between successful and failed IUI cases. It is concluded that only a limited group of couples may benefit from IUI.