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Artificial insemination techniques were originally used mainly to assist heterosexual couples to conceive where they were having difficulties. With the advancement of techniques in this field, notably ICSI, the use of artificial insemination for such couples has largely been rendered unnecessary. However, there are still reasons why a couple would seek to use artificial insemination using the male partner's sperm. In the case of such couples, before artificial insemination is turned to as the solution, doctors will require an examination of both the male and female involved in order to remove any and all physical hindrances that are preventing them from naturally achieving a pregnancy including any factors which prevent the couple from having satisfactory sexual intercourse. The couple is also given a fertility test to determine the motility, number, and viability of the male's sperm and the success of the female's ovulation. From these tests, the doctor may or may not recommend a form of artificial insemination. The results of investigations may, for example, show that the woman's immune system may be rejecting her partner's sperm as invading molecules. Women who have issues with the cervix – such as cervical scarring, cervical blockage from endometriosis, or thick cervical mucus – may also benefit from artificial insemination, since the sperm must pass through the cervix to result in fertilization.