For transillumination a torchlight can be used in a dark room and it is pressed against the scrotum and the fluid inside the scrotum - shines and light up. A tube made up of black paper can be used to view the illumination if it is not dark.
A smooth, cystic feeling mass completely surrounding the testicle and not involving the spermatic cord is characteristic of a hydrocele. The consistency of hydroceles can vary with position. Sometimes a hydrocele can become smaller and softer on lying down and become larger and tenser after prolonged standing.
Hydroceles are generally painless. The presence of pain, redness and edema with loss of the normal scrotal rugae is suggestive of an inflammatory lesion like epididymitis or epididymo-orchitis or filarial relapses.