Fertilizing capacity and sperm antibodies in vasovasostomized men

In order to explain the discrepancy between the patency rate (80%) and the pregnancy rate (46%) in a series of vasovasostomies, attention was focused on a group of patients who became normospermic. The mean age at vasectomy, the duration of vasobstruction, and the parameters of semen analysis were not different for those couples who achieved a pregnancy (n = 8), compared with those couples without pregnancy (n = 7). In the group with pregnancy, six of the eight patients had low titers of serum agglutinins (absent to 1:32), and the fertilizing capacity of their spermatozoa was normal. None had immobilizing antibodies. In the group without pregnancy, six of the seven patients had elevated serum agglutinins (greater than 1:256), and four had agglutinating antibodies in their seminal plasma as well as serum immobilizing antibodies. The spermatozoa of seven patients failed to fertilize zona-free hamster ova. It is concluded that a loss of fertilizing ability of the spermatozoa due to sperm antibodies is an important cause of infertility in vasovasostomized men.