A testis that has failed to descend from the abdomen to the scrotum. The condition usually affects only 1 testis and occurs in about 1 per cent of full-term and 10 per cent of premature male babies. An undescended testis often descends within months of birth but rarely descends after this time. An undescended testis does not develop normally, is incapable of normal sperm production, and is at increased risk of developing testicular cancer (see testis, cancer of). If both testes are undescended, infertility results.
A diagnosis is made during a physical examination after birth or later in infancy.
Treatment is by orchidopexy, which usually reduces the risk of later infertility or testicular cancer (see testis, cancer of).
A poorly developed undescended testis may be removed if the other is normal.
  
  
    A rare, cancerous tumour of the testis. Testicular cancer is most common in young to middle-aged men, and the risk increases in individuals with a history of undescended testis (see testis, undescended). The most common types of testicular cancer are seminomas, which are made up of only 1 type of cell, and teratomas. The  cancer usually appears as a firm, painless swelling of 1 testis. There may also be pain and inflammation. Biopsy, followed by orchidectomy, is the usual treatment, and may be combined with  chemotherapy. The tumours usually respond well to treatment.... testis, cancer of  
  
  
   
    
  
  
    A testis that is absent  from the scrotum because it has descended  into an abnormal position, usually  in the groin or at the base of the penis.  The condition is most often discovered  soon after birth during a routine physical  examination. It is treated by orchidopexy.  (See also testis, undescended.)  ... testis, ectopic  
  
  
   
    
  
  
    Pain in a testis may  be caused by mild injury, a tear in the  wall of the testis due to a direct blow,  orchitis, epididymo-orchitis, and torsion  of the testis (see testis, torsion of). Sometimes,  no cause is found and the pain  disappears without treatment. If the wall  of the testis is torn, an operation to  repair it may be needed.  ... testis, pain in the  
  
  
   
    
  
  
    Swelling  of the testis or the  surrounding tissues in  the scrotum. Harmless  and painless swellings  include epididymal cysts,  hydroceles, varicoceles,  and spermatoceles. Cancer  of the testis (see  testis, cancer of) is rare  but may be a cause of  painless swelling. Swelling  that is painful may be caused by a  direct blow, torsion of the testis (see  testis, torsion of), orchitis, epididymoorchitis,  or, in very rare cases, cancer of  the testis. Any swelling of the testes  should be assessed promptly by a doctor.... testis, swollen