Causes. Near the end of gestation, a male infant's testicles drop into the scrotum. The sacs surrounding the testicles close and the fluid within is dissolved into the body. Sometimes, however, the sacs do not close, or else the fluid inside does not dissolve. This can result in hydrocele in newborns. Concerning occurrences in older males, the sac might not close fully and might become filled with fluid from the stomach cavity. Also, inflammation of, or injury to the testicles could cause them to fill with fluid. Other causes of hydrocele include cancer in the kidneys or testicles.
