Hypoosmotic swelling test in patients with varicocele.

The hypoosmotic swelling test is a simple test for measuring the functional competence of human sperm membrane. Thirty-five patients with varicocele were assessed by hypoosmotic swelling test and the results were compared with those in patients with idiopathic infertility. Percentage of swollen sperm in varicocele tended to be lower than that in idiopathic infertility, especially in sperm concentration between 30 x 10(6)/mL and 40 x 10(6)/mL. Varicocele with sperm motility of 40% or more revealed lower percentage of swollen sperm than idiopathic infertility did. The results indicate that varicocele may particularly injure sperm membrane function because hypoosmotic swelling test is a test for measuring functional ability of human sperm membrane. The percentage of swollen sperm recovered after the operation earlier than did the other sperm parameters such as sperm concentration or motility, which indicates that impaired sperm membrane injury by varicocele is reversible.