A current Milex wide seal diaphragm fitting set.
Being fitted for a diaphragm or cap: On another forum a friend asked “How does a woman get fitted for a diaphragm or cervical cap?” I’ve written a great deal about the delights and problems with wearing a contraceptive diaphragm or cap, but I can’t recall ever posting about how one is fitted so I thought I’d write about that now.
Tools: The fitter should use a diaphragm fitting set. Currently available sets used in the U.S. contain one diaphragm in each of the five most commonly prescribed sizes (65 – 85mm) and the sizes are standardized across manufacturers in 5mm increments. I use an old Milex fitting set because it has the most sizes, eight, from 60mm to 95mm and they are silicone. The most recent Milex fitting set is shown in photo accompanying this post. If a fitter tells you that s/he doesn’t need a fitting set to properly size your diaphragm (and sometimes we get a patient who has been told that) you should terminate the visit and go to someone who knows what they are doing.
The fitting: For this discussion I’m assuming that the patient’s vagina isn’t blocked by an inelastic hymen that would prevent proper fitting and possibly intercourse and that her pelvic anatomy; post-pubic vault and cervical aspect will permit the effective use of a diaphragm. A bimanual (the first two fingers of the hand) exam is performed before which the bladder and bowels should be emptied. During the exam the fitter determines the tone of the pelvic floor, the amount of relaxation (which determines if an arcing, coil or flat spring rim would be best) and the depth of the vagina.
The distance from the posterior fornix to the back of the pubic bone is estimated by inserting the two fingers of a gloved hand behind the posterior fornix then bringing the thumb knuckle to rest on the pubic symphysis then removing the fingers with the thumb still in place. The distance from the longest finger to the thumb knuckle joint establishes the approximate size. With the thumb still in place the closest diameter diaphragm is selected from the fitting set to cover that distance. That’s the starting point.
I first try that one and if it seems to fit well I’ll try one size larger and one size smaller and have the patient feel the difference in the distances between the anterior rim and the back of her pubic bone for each so she knows what the rim of a correctly sized diaphragm feels like when checking with her fingers. Then I’ll have her walk around with the correct diaphragm inserted to show her than when properly inserted she can’t feel it. After which I’ll show her how to insert it and let her insert and remove the device several times while I’m there to answer questions.
Ideally, a woman using a diaphragm should have a pronounced post-pubic vault so the rim can be tucked up behind the pubic bone out of the way of a thrusting penis. A woman with a shallow or no post-pubic vault is not a good candidate because the anterior rim may be easily hit by the woman’s partner. With a properly fitted D in the unaroused state the woman should just be able to insert a finger between her pubic bone and the rim with the pad against the back of her pubic bone and the nail against the anterior rim.
It’s important that the patient should be unaroused during her fitting. She needs the largest size she can comfortably wear when unaroused. If she becomes aroused during her fitting she may be fitted with a too large diaphragm since when aroused the vagina lengthens (tents). Or, in an attempt to compensate for her arousal a fitter may prescribe a size that is too small for the patient. This may explain why some fitters seem to be prescribing diaphragms that are too small. A too large diaphragm, in addition to being uncomfortable, will press on the urethra and restrict urine flow which can contribute to a UTI. So it’s necessary to be very professional and quick when fitting patients. Even so quite a few patients become at least partially aroused. A too small diaphragm can be difficult to place correctly, more easily under-thrust and difficult to remove.
A woman should insert her D when she is not aroused. If she inserts when aroused, because the vagina lengthens, it becomes difficult and sometimes impossible to insert the D correctly. When that happens the posterior rim may go into the anterior fornix and the D is comfortable (as long as she remains aroused) while her cervix is unprotected. That’s why it is very important once the woman thinks her D is correctly placed, to feel with her fingers for her cervix under the dome. If she can’t feel her cervix under the dome it is not protecting her and she should remove and reinsert it.
The correct size of a diaphragm is weight sensitive. If a woman has a weight change of +/- 7 pounds she should have her fit checked. Typically (but not always) a weight gain will require a smaller size and a weight loss will require a larger size. A check to see if the diaphragm is too large, and pressing on the urethra, is to insert the diaphragm correctly when unaroused then urinate. There should be no restriction in urine flow. A properly sized and correctly inserted diaphragm is just as effective for parous women as nulliparous ones.
Cervical cap fitting: Currently there is only one cervical cap available in the U.S., FemCap. The maker’s website www.femcap.com has fitting guidelines that stress the woman’s obstetrical history as being the primary factor in determining which cap she should choose. However, it is a very good idea to have a proper fitting by an experienced FemCap fitter because aside from OB history some women’s cervix are larger or smaller than ‘the average’ (I take a 26mm when the guidelines say I should wear a 22mm) and some may have an anteverted or retroverted cervix that makes them a poor candidate for FemCap. That’s because the outer wall of the brim should seal flush against the vaginal wall and if the cervix is tipped significantly part of the brim won’t seal properly and will stick out where it will be hit by a thrusting penis. A properly fitting FemCap should seal flush against the vaginal wall and not touch the walls of the cervix. Contraceptive Technology says that FemCap is less effective for women who have given birth than for those who haven’t. FemCap can be purchased on-line w/o an Rx, but if you have purchased the wrong size or the cervix isn’t positioned to allow a good seal against the vaginal walls you are out the money for a device you can’t use.
Cervical caps like the Prentif cavity rim and Oves (now no longer generally available) were sized differently as they developed their seal by fitting tightly against the wall of the cervix, which meant that women who were good candidates for Prentif or Oves needed a smooth walled cervix with no flat spots, bumps or irregularities from birth trauma.