Diaphragm (contraceptive) - Fitting

Fitting

Diaphragms come in different sizes. A fitting appointment with a health care professional is necessary to determine which size a woman should wear.

A correctly fitting diaphragm will cover the cervix and rest snugly against the pubic bone. A diaphragm that is too small might fit inside the vagina without covering the cervix, or might become dislodged from the cervix during intercourse or bowel movements. It is also more likely that a woman's partner will feel the anterior rim of a too-small diaphragm during intercourse. A diaphragm that is too large will place pressure on the urethra, preventing the bladder from emptying completely and increasing the risk of urinary tract infection. A too-large diaphragm may also rub a sore on the vaginal wall.

Diaphragms should be re-fitted after a weight change of 4.5 kg (10 lb) or more. The traditional clinical guideline is that a decrease in weight may cause a woman to need a larger size, although the strength of this relationship has been questioned.

Diaphragms should also be re-fitted after any pregnancy of 14 weeks or longer. Full-term vaginal delivery especially will tend to increase the size diaphragm a woman needs, although the changes to the pelvic floor during pregnancy mean even women who experience second-trimester miscarriage, or deliver by C-section, should be refitted.

Vaginal tenting, an increase in the length of the vagina, occurs during arousal. This means that during intercourse, the diaphragm will not fit snugly against the pubic bone because it is carried higher up the vaginal canal by the movement of the cervix. If the diaphragm is inserted after arousal has begun, extra care must be taken to ensure the device is covering the cervix.

A woman might be fitted with a different size diaphragm depending on where she is in her menstrual cycle. It is common for a woman to wear a larger diaphragm during menstruation. It has been speculated that a woman may be fitted with a larger size diaphragm when she is near ovulation. The correct size for a woman is the largest size that she can wear comfortably throughout her cycle.

In the United States, diaphragms are available by prescription only. Many other countries do not require prescriptions.