Diaphragm effectiveness

Originally Published: March 9, 1995 - Last Updated / Reviewed On: August 8, 2008
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Dear Alice,

How effective is the diaphragm? I was on the pill, but it made me ill and depressed. However, I miss the spontaneity and reliability of it. What about the cervical cap?

Just Say No to Hormones

Dear Just Say No to Hormones,

Both the diaphragm and cervical cap are barrier methods of contraception. They work by physically blocking the sperm from entering the cervical opening and are designed to be used with spermicidal jelly or cream, creating a double form of contraception: physical and chemical. The diaphragm is made of rubber and is in the shape of a shallow cup. The cervical cap is made of silicone and is more like a small sailor hat. When a diaphragm is fitted correctly, and used correctly and consistently, the success rate is fairly high; about 94 percent. The effectiveness of the cervical cap (sold under the brand name Fem Cap) ranges from 71 to 86 percent, depending on if the woman has previously given birth. In the United States the Fem Cap is only brand of cervical cap available.

Using a diaphragm
You can insert a diaphragm, containing spermicide, before intercourse. It needs to be left in for at least six hours after sex. If you have sex a second time, add more spermicide without removing the diaphragm by using the applicator. The size of the diaphragm you use depends on the shape and contour of your vagina and the muscle strength of the surrounding vaginal walls. A health care provider will do an examination and fit you for the proper size. The provider will also teach you how to insert and remove the diaphragm. It's a good idea to practice taking it in and out a few times before you leave the office.

Using a cervical cap
A cervical cap is smaller than a diaphragm. A smaller amount of spermicidal cream or jelly is applied to both sides of the cap, which also needs to be left in place at least six hours after sex. The cap is designed to provide an almost airtight seal around the cervical opening. An advantage of the cervical cap is that it can left in for up to 48 hours. For example, you could put in on a Friday night and leave it through Sunday evening. The cervical cap is also fitted by a health care provider; however, it only comes in limited sizes which do not fit all women.

One point to consider for either method is that some people become irritated from spermicide, and may be more likely to experience urinary tract infections or vaginitis when using spermicide. If you know you experience irritation from spermicide, these methods may not be the best choice for you. In order to discuss the diaphragm or cervical cap, or other methods of birth control, with a health care provider students at Columbia can make an appointment at Primary Care Medical Services by logging into Open Communicator or calling x4-2284. If you're not at Columbia, see your regular gynecologist or women's health care provider.

A quick note on the depression you mentioned while on the pill. Switching to a lower dose pill, or a continuous-release method such as the vaginal ring, may help. You can discuss all of this, including your desire for spontaneity combined with reliability, with your health care provider to decide what form of contraception will work best for you.