Diaphragm Vs. Cervical Cap: What’s the Difference?

Aug 26, 2022

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Diaphragm Vs. Cervical Cap: What’s the Difference?

Barrier methods are old school. There’s a reason for that–it’s because they provide a simple solution that can be effective without the major side effects of hormonal birth control.

Two of the oldest barrier methods that have been in use since the 1800s, and are still in use today, are the diaphragm and cervical cap. These two methods sound very similar, but they are a little different. Here, we will be covering those differences.

Shape & Size

If you’ve ever seen a diaphragm, you’ll notice it looks like a miniature version of the invisible dome in the Stephen King-based television series “Under the Dome.” It’s basically a half sphere with a sturdy, flexible rim.

What Makes up the Diaphragm Shape?

It takes two components to make up the diaphragm’s dome shape. First, a large, flexible spring or wire forms a circular structure about four inches in diameter. The second component is the latex or silicone material laid across the spring and encapsulating it so that the entire diaphragm is soft and rubbery.

A New Shape for the Old Diaphragm

In the past decade, a new shape has entered the arena. Caya is the first contoured diaphragm. This means that both the spring and the silicone material are shaped to fit a woman’s body, rather than forcing the traditional circular shape to fit.

Cervical Caps - What Do They Look Like?

So what do cervical caps look like? They are much smaller than diaphragms and cup-shaped. FemCap is the only cervical cap available in the United States, and its shape can be described as looking like a tiny sailor’s hat. The material is 100% medical grade silicone with no wire or spring required. FemCap was designed to use its special shape to trap sperm.

Why the different shapes?

The diaphragm covers a larger area which includes the cervix; it depends on the walls of the vagina to stay in place, and spermicide goes on the cervix-facing side. The cervical cap only covers the cervix and the “hat brim” touches the walls of the vagina to trap sperm inside a crevice. Spermicide is not always required, but it’s usually recommeded for the cervical cap on the outside facing side.

Related: Why You Might Want to Ask Your Online OBGYN about Diaphragms

Fittings & Range of Sizes Available

When it comes to getting fitted for your diaphragm or cervical cap, these both used to require an in-person exam and fitting by your doctor. That’s because both barrier methods previously came in

multiple sizes. Traditional diaphragms come in around eight different sizes!

One-Size-Fits-Most Option Comes to Town

However, the diaphragm has evolved to include the contoured option that is labeled as one-size-fits-most and therefore requires no awkward fitting, as mentioned earlier, this version is called Caya. Since we are all unique, if you find that this single size doesn’t fit you, there are still other barrier options available to you.

No Fittings Required

FemCap, the modern cervical cap available on the market, has three sizes. The great news is, despite the options, no in-person fitting is required by your doctor. You can get your prescription sized based on whether or not you have been pregnant and whether that birth was vaginal or cesarian.

Effectiveness of Pregnancy Prevention

Both the cervical cap and diaphragm are similar in doing the job of covering the cervix to prevent pregnancy when used properly; however, one of them is slightly more effective. Used with spermicide, the diaphragm has an average failure rate of 18%, and the cervical cap has a failure rate of 20%.

Spermicide Increases Effectiveness

Both methods become more effective when spermicide is used together with the devices. It’s also notable that the cervical cap may have decreased effectiveness for women who have given birth.

The modern version of the diaphragm, Caya, has a 14% failure rate with perfect use, and 18% with typical use. The modern version of the cervical cap, FemCap, has a failure rate of about 8% during clinical trials, meaning it actually might be even more effective at pregnancy prevention than a diaphragm.

Set it and Forget it (for 1 or 2 days)

It’s notable that FemCap can be left in place for up to 48 hours while the diaphragm must be removed every 24 hours. Both methods require a six-hour window after sex before removing the device. These timeframes are important to keep in mind when deciding which method will work best for your lifestyle.

Related: Hormonal Migraines: How Your Las Vegas OBGYN Can Help

Similar Side Effects

Both the diaphragm and cervical cap have very limited side effects when compared to hormonal birth control methods. The main side effects of a diaphragm are the possibility of irritation and increased urinary tract infections (UTIs). The cervical cap has listed irritation as a side effect, as well as allergic reactions and the possibility of abnormal pap test results.

The FemCap claims to have a lower risk of urinary tract infections, but traditional cervical caps have a history of some other side effects, including:

  • Burning during urination
  • Pain while wearing
  • Blood during removal
  • Itching
  • Redness
  • Swelling
  • Abnormal discharge

It’s also important to consider that spermicide can cause some side effects as well. Since both the cervical cap and diaphragm recommend adding spermicide to their devices, don’t forget to factor this into your decision as you’re choosing the right barrier method.

The Final Comparison

If you’re looking for a non-hormonal birth control method, both cervical caps and diaphragms are worthy options to consider. Using the information above, we hope that we’ve cleared up what the main differences are between the two.

At My Virtual Physician, we are here to support you in choosing the right contraceptive option for you. Set up an appointment today, and we’ll help you get the prescription that is right for your body and lifestyle.


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Disclosure: My Virtual Physician has partnered with Caya to make it easy to provide a simple, hormone-free contraceptive solution to our patients.