This can be due to:

• One testicle not descending into the scrotum during normal embryonic or fetal development (3–4% of ‘normal’ live births), also known as: undescended testis or cryptorchidism. In this case the testis is within the abdominal cavity, somewhere along the normal route of descent — most commonly, within the inguinal canal. Such a testis has an increased risk of malignancy.

• One testicle may disappear during development (the so called vanishing testis) due to some intrauterine insult. This is thought most likely vascular, such as testicular torsion.

• One testicle being surgically removed through Orchidectomy

It has been claimed that both Hitler and Napoleon were afflicted by such a lack of symmetry, and suggested that this may have played a role in their particular psychological makeup. See Hitler Has Only Got One Ball.

Former Australian politician Mark Latham^[1], American bicyclist Lance Armstrong^[2] and Canadian comedian/actor Tom Green^[3] all have monorchism, as one testicle was removed to treat testicular cancer in each case. The late Frank Church, U.S. Senator (D-Idaho) from 1957 to 1981 and a Presidential aspirant in 1976, also had monorchism, having had one testicle removed in the late 1940s while attending Stanford Law School. Although Church had been given only a year to live, the surgery plus X-Ray treatment put the cancer into remission. Church eventually lived until 1984, when he succumbed to pancreatic cancer[1], a quarter-century later. His monorchism was revealed publicly during the 1976 Presidential campaign.

An individual having monorchism can be referred to as monorchid.

Template:WikiDoc Sources