Inflammation or injury of the scrotum causes testicular hydrocele in older males, according to Mayo Clinic. Infants can also develop hydroceles before birth. Fluid-filled sacs accompany a developing baby's descending testicles. The sacs usually close before birth. Communicating hydroceles occur if the sac remains open.
Infection of the testicle or small tube at the rear of each testicle can cause inflammation, which results in testicular hydroceles, as stated by Mayo Clinic. Typically, the only symptom of testicular hydroceles is a painless swelling of the testicles. Individuals with scrotal swelling should schedule an appointment with their doctor for a full evaluation.