CausesBy Mayo Clinic Staff
An overactive muscle causes a testicle to become a retractile testicle. The cremaster muscle is a thin pouch-like muscle in which a testicle rests. When the cremaster muscle contracts, it pulls the testicle up toward the body.
The main purpose of the cremaster muscle is to control the temperature of the testicle. In order for a testicle to develop and function properly, it needs to be slightly cooler than normal body temperature. When the environment is warm, the cremaster muscle is relaxed; when the environment is cold, the muscle contracts and draws the testicle toward the warmth of the body. The cremaster reflex can also be stimulated by rubbing the genitofemoral nerve on the inner thigh and by extreme emotion, such as anxiety.
If the cremaster reflex is strong enough, it can result in a retractile testicle, pulling the testicle out of the scrotum and up into the groin.
Causes of an ascending testicle
Some retractile testicles can become ascending testicles. This means the once-movable testicle becomes stuck in the "up position." Contributing factors can include:
Sept. 16, 2015
- Short spermatic cord. Each testicle is attached to the end of the spermatic cord, which extends down from the groin and into the scrotum. The cord houses blood vessels, nerves and the tube that carries semen from the testicle to the penis. If growth of the spermatic cord doesn't keep pace with other body growth, the relatively short cord might pull the testicle up.
- Remnants of fetal tissues. Abnormal remnants of fetal tissues that created the path for normal testicular descent might affect the growth or elasticity of the spermatic cord.
- Scar tissue from hernia surgery. An inguinal hernia is caused by a small gap in the abdominal lining through which a portion of the intestines can protrude into the groin. Scar tissue following surgery to repair the hernia might limit the growth or elasticity of the spermatic cord.
- Keys C, et al. Retractile testes: A review of the current literature. Journal of Pediatric Urology. 2012;8:2.
- Kliegman RM, et al., eds. Disorders and anomalies of the scrotal content. In: Nelson Textbook of Pediatrics. 20th ed. Philadelphia, Pa.: Saunders Elsevier; 2015. http://www.clinicalkey.com. Accessed Aug. 2, 2015.
- Cooper CS, et al. Undescended testes (cryptorchidism) in children: Clinical features and evaluation. http://www.uptodate.com/home. Accessed Aug. 2, 2015.
- Agarwal PK, et al. Retractile testis—Is it really a normal variant? Journal of Urology. 2006;175:1496.
- Gearhart JP, et al., eds. Cryptorchidism. In: Pediatric Urology. 2nd ed. Philadelphia, Pa.: Saunders Elsevier; 2010. http://www.clinicalkey.com. Accessed Aug. 2, 2015.
- Hack WW, et al. Acquired undescended testis: Putting the pieces together. International Journal of Andrology. 2012;35:41.
- Stec AA, et al. Incidence of testicular ascent in boys with retractile testes. Journal of Urology. 2007;178:1722.
- Cooper CS, et al. Undescended testes (cryptorchidism) in children: Overview of management. http://www.uptodate.com/home. Accessed Aug. 2, 2015.
- Kolon TF, et al. Evaluation and treatment of cryptorchidism: AUA guideline. Journal of Urology. 2014;192:337.
- Granberg CF (expert opinion). Mayo Clinic, Rochester, Minn. Sept. 2, 2015.