The effect of various degrees of unilateral spermatic cord torsion on fertility in the rat.

Unilateral spermatic cord torsion has been shown to cause damage to the contralateral testis in humans and animal models. In an attempt to explain conflicts among various laboratories concerning the extent of this contralateral effect and to determine the importance of the extent of torsion, prepubertal rats (35 to 40 days) were subjected to unilateral spermatic cord torsion of various degrees (zero to 1440 degrees). Sham surgeries were performed and served as controls (0 degrees of torsion). The animals were allowed to recover from the surgeries and to attain puberty before a period of fertility testing. Fertility, fecundity, organ weight and testicular histological data were obtained after the breeding period. Our data indicate that animals undergoing 360 degrees of torsion exhibited no changes in the parameters studied. However, if 720 degrees, 1080 degrees or 1440 degrees of torsion was induced, a significantly lower percentage of fertile males and pregnant females resulted for each of these experimental groups when compared to those values for the 0 degrees controls. These data indicate that the extent of contralateral testicular degeneration is dependent upon the degree of spermatic cord torsion to which the ipsilateral testis is subjected. The induction of unilateral spermatic cord torsion at 720 degrees or more causes a significant reduction of subsequent fertility while torsion of a lesser degree has little or no effect in the development of this phenomenon.