What is a hydrocele?

A hydrocele is produced by fluid in the sac which normally surrounds the testicle. It often presents as painless swelling in the scrotum (the pouch that holds the testicle). Hydroceles are often found in newborn boys, especially premature infants.

The majority of hydroceles in newborn males will get better on their own as the channel shrinks down. Those that do not get better on their own may require surgical correction as they are due to a channel (or tube) that connects the abdomen to the scrotum (called a communicating hydrocele), allowing the abdominal fluid to drain into the scrotum. Hydroceles can also occur in older boys during puberty or as an adult.

Hydroceles that occur in boys during puberty (or pubertal development) are adult-type hydroceles. These typically have no channel connecting the abdomen to the scrotum, but simply represent over-production of fluid by tissue surrounding the testicle. If they become large, surgical correction may be necessary. It is important that this type of hydrocele be evaluated, as it may occasionally be an early sign of testicular tumor.

Here is an image of a normal scrotum, one with a non-communicating hydrocele, and one with a communicating hydrocele. 

What is a non-communicating hydrocele?

When a boy has a non-communicating hydrocele there is no connection between the abdominal cavity and the sac around the testicle in the scrotum. This type of hydrocele is often found in newborns and these often resolve or go away over time. It may take up to one year for this to happen, but as long as the swelling is decreasing, it can be safely observed.

If your son is older and has this kind of hydrocele it is termed an “adult-type” hydrocele. These may be produced by other problems, such as infection, torsion (twisting of the testicles), or a tumor, so examination by a physician is critical if swelling occurs in the scrotum in an older child or adolescent.

What is a communicating hydrocele?

When the sac does not close, the hydrocele is called communicating or open. This means that the fluid around the testicle can flow back up into the abdomen. You might notice that the hydrocele looks smaller early in the day and larger in the evening. This may be due to your child being upright all day. It may also look smaller when your son's doctor presses on his scrotum, as the pressure may cause the fluid to flow back into the abdomen.

What causes a hydrocele?

During the seventh month of fetal development, the testicles move from the abdomen into the scrotum. When the testicle travels downward, it brings the sac-like lining of the abdominal cavity with it. The sac allows fluid present in the abdomen to surround the testicle. This sac usually closes before birth, preventing additional fluid from going from the abdomen into the scrotum, and the fluid is absorbed.

Are hydroceles dangerous?

Hydroceles are not harmful to the testicles in any way and they don't cause your son any pain. Sometimes, however, if the sac remains open, a loop of intestine can be pushed through the opening creating a hernia. If your son's scrotum suddenly appears very large and hard, and he will not stop crying, call the doctor right away. Your son may need immediate attention.