Hydroceles occur when fluid fills a sac in the scrotum of the penis (in the "inguinal canal"). About 10% of male infants have a hydrocele at birth. They can also develop with swelling or injury of the scrotum.
An inguinal hernia occurs if a small part of the intestine drops into the scrotum with the testes. The intestine can form a lump in the scrotum. There are two kinds of inguinal hernias. Indirect inguinal hernias occur in about 1% of baby boys, the rate is higher in premature infants. Direct inguinal hernias are fairly common in older adult males.
Hydroceles and inguinal hernias can become a problem for males. Females do not get hydroceles, but they can get hernias. Ten times more males get hernias than females.