Most abnormalities in the size and structure of the testicles and scrotum are typically discovered at birth. The most common abnormalities occur when a testicle is not found in the scrotum. This can for a number of reasons. We will also discuss abnormalities in the size of the testicles and scrotum – both smaller than normal and larger than normal.
Missing Testicle (Cryptorchidism)
The medical term cryptorchidism literally means “hidden testicle.” The testicles form inside a boy’s body during fetal development. Normally the testicles descend through the inguinal canal shortly before birth. There are a few reasons why a testicle may be missing, but the most common are due to the testicle either not descending into the scrotum or retracting/ascending out of the scrotum. Other causes are wandering (ectopic) testicles or lack of testicles forming at all (anorchia). These are usually discovered and corrected in infancy.
Most boys are born with both testicles being present in the scrotum. However, a boy can be born with one or both testicles not descended. This occurs more in premature infants. This is often referred to as cryptorchidism. This typically will resolve itself within a few months. If one or both testicles do not drop into the scrotum in the first few months (usually by age 4 months), then surgery can be performed to relocate them into the scrotum. It is important that the testicles drop into the scrotum; otherwise, complications with hormone levels and fertility in the future may be affected. In addition, testicular cancer risk increases the longer the testicles remain inside the body rather than in the scrotum. To the right[i] is an image of a pre-pubescent boy with an undescended testicle. As you can see, there is a testicle in one side of the scrotum, but the other side of the scrotum is flat, having no testicle residing within it.
Retractile & Ascended Testicles
In some cases, a testicle may appear to “go missing.” This can be caused by two different but very similar conditions.
The first is a retractile testicle. This happens when contractions of the cremaster muscles or other muscles cause the testicle to retract back into the inguinal canal so that the testicle cannot be felt in the scrotal sac. Typically, a retractile testicle can be guided back into the scrotum. In most cases the inguinal canal will close before puberty. However, some adult men have retractile testicles and often notice this occurring when their cremaster muscles contract (they notice this during cold weather, stepping out of a hot shower into a cold room, or when they get an erection).
In a few rare cases the testicle may retract so far that it cannot be guided back down into the scrotum and it remains in the abdomen. This is called an ascended testicle. Ascended testicles often require surgery to correct their position back into the scrotum. As with undescended testicles, ascended testicles can lead to infertility and hormone deficiencies later in life and increase the risk of testicular cancer. Speak with a healthcare provider if you or your son have issues with retractile testicles and especially with ascended testicle(s).
Wandering or Ectopic Testicle
In this case, the testicle developed normally during pregnancy; however, the testicle did not make it into the inguinal canal in order to descend into the scrotum. Ectopic testicles may be located inside the abdomen, just under the skin of the pubic area, under the skin of the thigh, near the scrotum (even behind the scrotum on the perineum where a man would sit), or even under the skin at the base of the penis. Clinically, these “wandering” testicles are called ectopic – meaning they grow outside of the normal space. Usually, the testicle is fully formed. Since the testicle is often fully formed, it is susceptible to injury. Especially if it is located near the surface where it can be hit or pressed against bone or muscle. Surgery is required in order to place the testicle into the scrotum as it will not “descend” to the scrotum over time.
Lack of Testicles (anorchia)
Anorchia is a condition when the testicles fail to develop during pregnancy or they disappear early on in pregnancy. If the testicles “disappear” and stop forming before 8 weeks, the baby will often appear to have female genitals since testosterone didn’t trigger the pathways to cause male genital growth. However, if the testicles disappear between weeks 8 and 10 of pregnancy, the genitals may have characteristics that look a little bit male and a little bit female. This is recognized at birth and options will be given to parents to correct any malformations.
If the testicles disappear between 12 and 14 weeks of pregnancy, other male genitals will have formed. In these cases, a boy is born with a penis and scrotum but there are no testicles in the scrotum. In anorchia, the testicles are not located anywhere else in the pelvic region – they are simply missing. Treatment for anorchia often includes the administration of testosterone at key times during life, especially during puberty and adulthood. Artificial testicles can also be placed inside the scrotum if that is desired to give the scrotum a more “normal” appearance.[ii]
[i] https://medlineplus.gov/ency/article/001185.htm (3/21/17)
[ii] SciencePhotoLibrary Undescended Testicle M865/0233
Images on this page from top to bottom include: