Barrier methods of contraception rely on placing some kind of obstacle in the vagina to prevent the passage of sperm into the uterus. Some, such as the diaphragm, covered the cervix, whereas the cervical cap was designed to fit only over the cervix and not block the vaginal canal as the diaphragm did. The problem was how to keep the cervical cap covering the cervix. The half of a lemon that Casanova used was a cervical cap but was difficult if not impossible to hold in place.
Rubber seemed a natural material for making a cap because it could be molded into place. From its first transmission into Europe from the Americas in the sixteenth century, rubber began to be used for a variety of medical products and the number of these gradually increased. Even before vulcanization it was widely used for various kinds of pessaries. One of the earliest medical references to what is clearly a cervical cap designed for contraceptive purposes was by Friedrich Wilde in 1838. He urged women who wished to avoid becoming pregnant to be fitted with a pessary made of unvulcanized rubber (or kauthuck in German). Wilde first took a wax impression of the cervix and then, using it as a pattern, designed a hard rubber pessary that would snugly cover the os, or entrance into the uterus (Wilde, 1838). Annie Besant prescribed its use as a contraceptive in the 1887 edition of her Law of Population, and other writers followed her example. Marie Stopes made the cervical cap her contraceptive of choice, and she helped design the modern ones, although a number of others were also involved.
The vaginal cup (cervical cap), popularized by Stopes, was a small thimble-shaped cup that effectively blocked the cervix when it was inserted properly. During the early years of the twentieth century, it was in competition with the diaphragm but it fell into disfavor in the United States (although not in Great Britain) in part because it took longer to fit properly and seemed more complicated to insert correctly than the diaphragm. It was also a source of dis comfort for a few users. Perhaps the key reason for its failure to become the barrier contraceptive of choice in the United States is that Margaret Sanger and the American Birth Control League advocated the use of the diaphragm. Still, the cervical cap had its strong advocates and its popularity increased in the 1970s through the advocacy of many feminist health organizations. This success was short lived because it ran into serious legal problems as a result of the Medical Device Amendment Act of 1976. The intention of the U.S. government in enacting the law was not to ban the cervical cap but only to have its manufacturers submit data on its safety and efficacy to the Food and Drug Administration (FDA) and give proof that it had been marketed in the United States before the law had been passed. This requirement applied to all manufacturers of all medical devices on the market before 1976 and had not especially singled out contraceptive devices. When the British manufacturer of the cap, for some unknown reason but probably the cost involved since it was not widely used in the United States, failed to provide the needed information, the FDA had no alternative and in 1979 placed the cap on its Class III list of devices—those that represented a significant risk to the user—and ordered the seizure of all cap shipments entering the country. It was not until 1988 after tests finally had been run and the data gathered together that the FDA announced its approval of one type of cap, the Prentif cavity-rim cervical cap. Once again the device was available in the United States to those women who preferred it.
The Prentif cavity-rim cervical cap currently in use is made of a soft, pliable latex and is about half the size of the diaphragm. It is available in four sizes with inside diameters of 22, 25, 28, and 31 mm. Two other caps, the vault (or Dumas) cap and the Vimule cap, have also been approved. Although they are not much used in the United States, they are in other countries. The vault, or Dumas, cap is made of rubber or plastic and shaped like a circular bowl with a thick rim and thin center. It clings by suction to the vault or roof of the vagina, following the contour of the cervix. It is useful for the woman who cannot accommodate a diaphragm because of poor muscle tone and for the woman who cannot use the Prentif cervical cap because her cervix is either too long or too short. The Dumas cap is available in five sizes ranging from 50 to 75 mm, and although the diameters are larger than those of the Prentif cavity-rim cup, this is because it, like the Vimule cap, covers the cervix and part of the upper vaginal vault, whereas the Prentif covers only the cervix. The Vimule cap is a longer bell-shaped cap made of thick rubber or plastic (more like the early ones) with a deep dome. It fits around the cervix but has a flanged rim that permits it to be pressed more firmly onto the roof of the vagina. It is most useful for a woman who has poor vaginal muscle tone, a cystocele, or a longer than average cervix. It is available in three sizes: 42, 48, and 54 mm. Like the diaphragm, the cup must be fitted by a professional.
Since the development of spermicides, users of the cup are also advised to put spermicidal jelly in the cup (until it is about one-third full) before inserting. Although barrier methods are no longer as widely used as they were for much of the twentieth century, the cap has some characteristics that its users believed, once they had mastered the insertion techniques, made it their contraceptive of choice. It can be left in longer (two to three days at a time) than the diaphragm, it does not create pressure on the bladder, and it does not block the stimulation of the anterior vaginal wall, which some researchers have identified as the site of the Grafenburg, or “G,” spot, a particularly sensitive area of sexual pleasure for some women. Failure rates are similar to those found by users of the diaphragm, that is, about ten per one hundred woman-years of use. This means that for every one hundred women using the cup with spermi-cide for one year, fewer than ten will become pregnant. However, improper fitting or insertion, which might cause the cap to be dislodged, is more likely than that among diaphragm users.
As with the diaphragm, more experienced users have lower failure rates and some would claim no more than two or three per one hundred woman-years.
