The sperm-mucus interface: patterns of disorder in the diagnosis of specific causes of penetration failure causing infertility.

In 94 infertile couples with negative postcoital tests (PCTs) the results of an in-vitro sperm-mucus invasion test (SMIT) were compared with seminal analysis (excluding sperm density less than 1 x 10(6)/ml) and agglutination assays for antisperm antibodies in semen (MAR, TAT) and in mucus (TAT). Abnormalities at the sperm-mucus interface were classed into three types. (i) Failure to form semen clefts and of spermatozoa to colonize the clefts was closely correlated with oligo-asthenoteratozoospermia, and vice versa, the two tests agreeing in 90% of cases (P less than 0.001). Most of the discrepancies, in which sperm-dense clefts developed despite low sperm counts, were due to antisperm antibodies in semen. (ii) Failure of spermatozoa to invade mucus, despite normal sperm colonization of clefts, was closely correlated with the presence of antisperm antibodies in semen (positive MAR or TAT), and vice versa, the tests agreeing in 81% of cases (P less than 0.001). (iii) Failure of sperm survival after normal invasion of mucus could not be correlated significantly with the TAT results on mucus, but more extensive study of this question is needed. Finally a normal SMIT result was associated with a significantly improved chance of conception (39 versus 10% at 12 months), particularly with artificial insemination, suggesting undisclosed coital failure as the cause of the negative PCT. In conclusion, the invasion test, when assessed in the foregoing detail, offers a reliable and simple substitute for laboratory assessment of both seminal quality and the presence of antisperm antibodies in semen, and would be applicable in general infertility practice everywhere.