Difference Between Cervical Cap and Diaphragm

Cervical cap and diaphragm are two barrier contraceptive methods. Both are moderately effective at preventing conception. However, both methods do not provide any protection against sexually transmitted diseases.

Cervical Cap

Cervical cap is a cup like device which fits over the cervix and prevents entry of sperm into the uterus through the external os. Many primitive methods were used to block the cervix to prevent conception in the olden days. Sticky resins, halves of lemons and cone shaped devices are a few such methods. The cup shaped device, which seals off the cervix against the upper vaginal wall, is a fairly new method. At the emergence of the modern cervical cap, uncured rubber cups were used to block the cervix. These gave allergies and degraded quickly. With modern advancements, spermicides were added to increase the effectiveness and better materials were used to create them.  A gynecologist or a related health care worker should screen the woman before fitting. A regular, unscarred normal sized cervix without any disorders like cervical fibroids would be ideal for a cervical cap.

The length of the cervix, parity, injury to the cervix, past surgeries like Manchester repair, cervical fibroids and other cervical growths affect the fitting and effectiveness of cervical caps. Common practical problems encountered at fitting are unavailability of the exact size and anatomical configuration. The rim of the cervical cap should be placed flush against the walls of the fornices. The cervical cap should be placed over the cervix before sexual intercourse and should remain inside the vagina for 6 to 8 hours after the last intra-vaginal ejaculation. Some schools suggest placement before sexual arousal to ensure correct placement. Many US brands recommend removal within 72 hours. Effectiveness differs between brands. Nulliparous women show a smaller failure rate than parous women.


Diaphragm is a silicone dome with a springy rim which lies flush against the vaginal walls and stretches across the cervix. A visit to the health care worker is essential to determine the correct diaphragm size. Diaphragm should rest snug against the pubic bone and in the posterior fornix. If the size is too small, it may get dislodged during bowel movement and intercourse. If the size is too large, it may constantly rub against the vaginal wall resulting in an ulcer. After washing hands to prevent contamination of the device, the diaphragm should be bent into an oval shape, to make insertion easier. Spermicide may be applied on to the edge of the diaphragm, to ease insertion. The diaphragm should be inserted some time before sexual intercourse. It should remain inside the vagina for 6 to 8 hours after the last intra-vaginal ejaculation. After the removal, it can be cleaned with soapy water and reinserted immediately. Care should be taken not to use oil based products with a diaphragm because they degrade the diaphragm quickly. Yearly failure rates of the diaphragm are from 10 to 40 per cent.

What is the difference between Cervical Cap and Diaphragm?

• Cervical cap is a cup shaped device with a tight rim while the diaphragm is a silicone dome with a springy rim.

• Cervical cap fits like a sock over the cervix while the diaphragm stretches from posterior fornix to the pubic bone with its rim flush against the vaginal wall.

• Cervical cap is marginally more effective than the diaphragm.