During the fitting process, a fitting ring is inserted into the vagina. The largest ring that fits comfortably is usually the size chosen. Diaphragms can be inserted up to two hours before sex, because spermicide is only effective for two hours. If the woman inserts her diaphragm more than two hours before intercourse, she will have to insert more spermicide into her vagina later (see box below for guidelines). As a general rule, diaphragms should be replaced every one to two years.

Guidelines for diaphragm insertion

Before or after each use, the woman should hold the diaphragm up to the light, or fill it with water, to check for holes, tears or leaks.
A small amount of spermicide (about one tablespoon) is usually placed inside the cup, and some is smeared around the lip of the cup.
The device is then folded in half and inserted into the vagina by hand, or with the assistance of a plastic inserter.
The diaphragm should fit over the cervix, blocking entry to the uterus.
If more than six hours pass before repeat intercourse occurs, the diaphragm can be left in place, and extra spermicide inserted into the vagina using an applicator.
The diaphragm must remain in the vagina for six to eight hours after the final act of intercourse, and can safely stay there up to 24 hours after insertion.
The diaphragm should be washed with soap and warm water after each use, and then dried and stored in its original container, which should be kept in a cool dry place.