Cryptorchidism means absent are undescended testis.
The commonest location of Undescended testicle is outside the external ring, followed by inguinal canal or in abdomen. The boys who are born with undescended testes correct itself with in the first few months. If it does not get corrected, surgery may be required to correct it.
The exact cause is not known. A combination of genetics, maternal health or other environmental factors may disrupt the hormones, physical changes and nerve activity that influence the development of the testicles.
It is very important for the boy's psyche to have two normal testes in the scrotum. This is often an underplayed argument.
Testes require a temperature slightly lower than the body temperature for sperm production. If they lie too close to the body, then over time the cells that produce sperms die leading to infertility. To minimize this damage Undescended testes need to be brought down to the scrotum by 6 months of age.
Undescended testes are often associated with a hernia which requires surgical correction.
If the testes remain in the abdomen for a long time, they have a slightly higher chance of developing a cancer. If testis is in groin area, it is more easily injured during play or accidents.