Diaphragms, caps, and shields are all barrier methods that prevent sperm from
reaching the uterus. Each method consists of a latex or silicone dome which fits
into the vagina, covering the cervix. Diaphragms are shallow domes which fit
snugly into the top of the vagina, while caps and shields are narrower and fit
snugly over the cervix itself.
All three of these devices require the use of spermicidal cream or jelly to
maximize protection, and each requires a pelvic exam at a physician’s office or
clinic in order to find the right fit.
Diaphragms, caps, and shields can be used within months of childbirth or
abortion, and are safe to use while breastfeeding. They can also be easily
carried in a purse or a pocket, and usually neither partner can feel it be felt
during intercourse. Spontaneity of intercourse is achievable since a woman can
insert her device hours ahead of time.
Also, these methods are immediately reversible should a woman decides to
become pregnant, and do not interfere with her natural hormonal cycles. However,
women with frequent urinary tract infections or a history of toxic shock
syndrome and those allergic to latex or silicone should not use diaphragms,
caps, or shields.
The failure rate with typical use is about 16%, and about 6% with perfect
use. The higher failure rate occurs because some sexual positions or angles may
dislodge the device, allowing semen to enter the uterus. An important
consideration is that these barrier methods do not prevent sexually transmitted
diseases, including HIV/AIDS.