The twisting of the spermatic cord due to an anatomical abnormality that left the testis mobile and dangling in the scrotum. The initial effect of testicular torsion is obstruction of venous return. Depending on the duration and degree of cord rotation, testicular symptoms range from edema to interrupted arterial flow and testicular pain. If blood flow to testis is absent for 4 to 6 h, spermatogenesis may be permanently lost.