Pelvic adhesions are usually caused by surgery or infection. Pelvic adhesions are actually scar tissue that forms between two or more internal organs. Infertility can occur when the adhesions attach to the ovaries or fallopian tubes. Polycystic ovarian disease is a hormonally based condition characterized by scanty or absence menstruation. The disease usually causes multiple cysts to form in the ovaries.
Some men also make antibodies to their own sperm.
Immunological infertility can sometimes be treated medically or with assisted reproductive techniques. The theory that immune system abnormalities cause miscarriages is controversial and needs more study. Varicocele is a major cause of male infertility and occurs when a vein that carries blood out of the scrotum dilates, much like a varicose vein in another location. As a result, a pool of blood forms around the testicles, raising the temperature of the scrotum. The elevated temperature hinders the maturation process of sperm, which develop best in an environment that is slightly cooler than body temperature.