A 25 mm Prentif cervical cap and hard shank Gaynors
The Prentif Cavity Rim cervical cap: The Prentif, approved by the FDA in the late 80s for use in the U.S as a contraceptive barrier, came in four sizes: 22, 25, 28, and 31mm, which were the internal dimensions of the base of the dome. I take a 25mm and bought several before the manufacturer, Lamberts, stopped making them in about 2005 and I continue to find wearing them fun. When forced down over a smooth walled cervix the cavity in the rim develops a strong suction that holds it securely on the cervix. Once the cap is properly positioned the tab on the shoulder of the rim (seen at about one-o’clock in the photo above) is used to turn the cap a full turn while pressing on the dome to ‘screw it down’ on the cervix.
When Prentif is used as intended, for contraception, it’s important to remember that the tab should be positioned behind the cervix after the turn to screw the cap down so that the edges aren’t hit by a thrusting penis. The Prentif, for those fortunate enough to have serviceable ones, can be worn continuously for 48 hours w/o using any additional spermicide. Prentif is as effective, about 94%, as a diaphragm for nulliparous women. For parous women cervical changes make the Prentif only about 85% effective. I think the biggest problem with the Prentif cap was that there was not size smaller than the 22mm, say about 19mm as a great many women who wanted to wear a Prentif had cervixes too small to be properly fitted.
Dimensions and fit: The 25mm cap is 4cm tall and when forced on to a typical 3 cm long cervix there is about a 2cm space between the tip of the cervix and the inside top of the dome. This space is usually partially filled with a spermicide as back-up contraception so if the cap displaces sperm will be immobilized by the spermicide in the dome. When the cap is suctioning well the vacuum in the domes of the 25 through 31 mm sizes will cause the top of the dome to dimple. The dome of the 22mm is too stiff to dimple under vacuum. A sign that the cap is too old and the latex is getting stiff is if the dome of 25mm and larger caps becomes permanently dimpled.
When I wore a Prentif as my primary method in the late 90s my fit was so tight that I never used spermicide in the dome and had to pry it off after a 48 hour wearing interval. If a woman wearing a 22mm Prentif was fertile and she wore the cap for the full 48 hour interval there was a possibility that the dome could fill with fertile cervical mucus and then when hit by a thrusting penis it could ‘float off’ her cervix. Even though I wear a 25mm I thought it was a good idea when fertile to wear Prentif for only 24 hours to make sure the dome wasn’t full and I didn’t have an accident.
Sado-Masochism and Prentif: The outer diameter of a 25mm cap is about 4cm at the base of the cap, thus increasing the diameter at the base of the cervix by about 1.5cm when the cap is properly positioned. The increase in length of the cervix by as much as 2cm (discussed above) and its diameter by 1.5cm increases the cervix ‘target’ size. This is a condition seemingly appreciated only by a few Prentif wearers and our partners in the BDSM community who enjoy cervical or penile glans battering (both of which are acquired tastes) if the man is not quite long enough to reach the cervix unaided.
Cervix battering: For cervix battering of a masochist partner most men don’t seem to mind thrusting into the Prentifs soft dome. The base containing the cavity rim is a bit stiffer, but if the shoulder tab is behind the cervix so it isn’t hit my partners say it’s not uncomfortable and often overlooked when the woman gasps or moans when he hits the dome straight on. If a nulliparous woman’s cervix is smooth and the cap correctly sized and screwed down tight a thrusting penis shouldn’t dislodge it.
Glans battering: For glans battering the shoulder tab is rotated so it faces the anterior wall of the vagina. That way the man is quite likely to hit the tab with some frequency. When glans battering is intended it’s best to have the man wear a well fitting cock ring to prevent him going flaccid when he hits the tab. Of course a man in a cock ring limits the duration of safe play to about 20 minutes. Very few male masochists can repeatedly hit the shoulder tab of a Prentif and retain an erection w/o wearing a cock ring. I’ve found that astride where I control the depth and direction of penetration or missionary where I’m wearing bedshoes to increase the range of my pelvic thrusts, are the best positions for battering a man’s glans.
Escorts, caution and the Prentif: For the few escorts who specialize in male penile sadism it’s a premium service. Using a Prentif that way takes experience (there are no classes) so she knows how to hit his glans a glancing blow with the tab to minimize the number of solid hits she takes to her cervix while causing him the most pain. That’s because uterine prolapse where the uterus drops into the vagina, is a common problem experienced by escorts who specialize in clients paying for rough cervical contact. Uterine prolapse in an escort is usually the end of her career since even with surgery afterward she is rarely the same.
In my teens it took me getting only a few solid blows to my cervix to learn to adjust my hips and pelvis to take glancing blows that stimulate my libido while minimizing the possibility of damage to the muscles and ligaments holding my uterus in place. Of course working out with Ben Wa balls as we all do is very good exercise to strengthen the pelvic muscles to avoid a prolapse.