A pessary is a smooth, flexible device made of medical-grade silicone that sits inside the vagina to support pelvic organs or, in some cases, the cervix during pregnancy. There is no single shape: pessaries come in rings, mushroom-like discs, cubes, doughnuts, and several other designs, each engineered for a different clinical situation. Understanding what these devices actually look like, how big they are, and why a particular shape might be chosen over another can make the whole fitting process feel far less mysterious.
The Ring Pessary
The ring pessary is the most widely used type, and it looks almost exactly like what the name suggests: a flexible silicone circle, similar in basic shape to a large, firm bracelet or a ring you might see in a gymnastics class. Most ring pessaries measure somewhere between about 50 and 100 millimeters in diameter, increasing in roughly 5- to 10-millimeter increments across available sizes. Some versions are completely smooth rings; others have a flat membrane stretched across the center, called a “ring with support,” which provides an extra shelf of material underneath the bladder or uterus. Both versions can be gently folded in half for insertion, much like pinching a soft taco shell, and then they spring back open once inside the vagina.
The ring’s simplicity is a big part of its appeal. Because it is open or only partially filled, it tends to produce lower contact pressure against the vaginal walls compared with bulkier designs.1Journal of Biomechanics. Finite element analysis-based evaluation of different pessaries for female cystocele intervention That lower pressure generally translates to better comfort for day-to-day wear and fewer issues with tissue irritation. It also means the ring can often stay in place during intercourse, which is a practical advantage many people care about.
Space-Filling Pessaries
When a ring does not provide enough support, usually because the prolapse is more advanced or the vaginal walls are too relaxed to hold a ring in place, clinicians turn to space-filling designs. These take up more room inside the vagina and work by physically occupying the space that prolapsing organs would otherwise fall into.
- Gellhorn: Shaped like a mushroom or a thick disc with a short stem protruding from one side. The flat disc sits against the vaginal walls while the stem points toward the vaginal opening, giving a clinician (or the wearer) something to grip during removal. Biomechanical modeling shows the Gellhorn is more effective than the ring at limiting organ displacement and reducing stress on supporting ligaments, though it can create concentrated pressure spots where the disc meets tissue.1Journal of Biomechanics. Finite element analysis-based evaluation of different pessaries for female cystocele intervention
- Cube: A soft silicone block with concave sides, roughly the size of a large die. The concavities create gentle suction against the vaginal walls, which helps it stay put even when the pelvic floor muscles are weak. Cubes must be removed nightly because of that suction and the difficulty of cleaning them in place.
- Doughnut: A thick, solid ring that looks like a small inflatable pool toy. It fills more space than a standard ring but does not have the stem of a Gellhorn. It is sometimes chosen when a ring is too small to stay in position but a Gellhorn is uncomfortable.
All of these space-filling designs require removal before vaginal intercourse because they physically block the vaginal canal.2PubMed Central. Sexual Function and Pessary Management Among Women Using a Pessary for Pelvic Floor Disorders That is one of the key trade-offs: they offer stronger support but demand more hands-on management than a ring.
How Sizes Work
Pessary sizes are measured by diameter (for rings and doughnuts) or by the width of the disc (for Gellhorns). Most manufacturers offer each design in a range of sizes, often eight to twelve per type, typically spanning from around 45 mm up to 95 mm or more. The numbering systems vary by brand, so a “size 4” from one company is not necessarily the same diameter as a “size 4” from another. What matters is the millimeter measurement.
Fitting is not a one-measurement process. A clinician usually starts with an estimated size, inserts it, and then asks the person to stand, walk, cough, and bear down to see if the device stays in place and feels comfortable. If it slips out or causes discomfort, a different size goes in and the test repeats. Research shows that the width of the vaginal opening and the total vaginal length both influence which size works, but no single measurement perfectly predicts the correct pessary diameter.3PubMed. Which factors should be considered in choosing pessary type and size for pelvic organ prolapse patients in a fitting trial? For ring pessaries with support, vaginal opening width and total vaginal length mattered most; for Gellhorns, the stage of prolapse also played a role in determining size.
Some clinicians are experimenting with ultrasound imaging to improve first-try accuracy. Transperineal ultrasound can measure the opening in the pelvic floor muscles and compare it with the pessary diameter, producing a ratio that helps predict whether a given size will stay in place.4PubMed Central. Transperineal ultrasound to estimate the appropriate ring pessary size for women with pelvic organ prolapse This approach is still not standard practice everywhere, but it points toward a future where fitting involves less trial and error.
One important finding from fitting studies: about nine in ten women can be successfully fitted with either an incontinence ring or a dish pessary, which is an encouraging success rate.5PubMed Central. Incontinence pessaries: size, POPQ measures, and successful fitting A pessary that is too small may not provide enough support, while one that is too large can press too hard on the vaginal lining and increase the risk of tissue injury.1Journal of Biomechanics. Finite element analysis-based evaluation of different pessaries for female cystocele intervention
What They Are Made Of
Modern pessaries are made of medical-grade silicone, a non-reactive material that can be cleaned, autoclaved, and reused for months or even years. This is a relatively recent development in a surprisingly long history. Earlier pessaries were fashioned from cork, brass, and later rubber, all of which had obvious drawbacks in terms of comfort and tissue reactions.6PubMed. The history and evolution of pessaries for pelvic organ prolapse Silicone solved most of those problems. It is soft enough to fold for insertion, firm enough to hold its shape once positioned, and it does not absorb odors or secretions the way rubber did.
Silicone pessaries do come in different firmness levels. The stiffness matters because a firmer device holds its shape better under load but can be harder to fold for insertion, while a softer one is easier to manage but may deform too easily to provide reliable support. Engineering studies have tested the mechanical properties of pessary silicone under tension and compression to model how different firmnesses perform during the folding and insertion process.7Journal of the Mechanical Behavior of Biomedical Materials. Hyperelastic material models for simulating deformation of silicone ring pessaries
How a Pessary Stays in Place
People are often surprised that a smooth silicone device can stay inside the body without falling out. The answer lies in the pelvic anatomy itself. The vagina is not a wide-open tube; it is a collapsed space surrounded by muscles, ligaments, and the other pelvic organs. A properly sized pessary rests behind the pubic bone and is held in position primarily by the levator ani muscle, the hammock-shaped muscle that forms the floor of the pelvis, along with a lever effect created by the uterus or the vaginal cuff in people who have had a hysterectomy.8PubMed. Differences in pessary support between successful and unsuccessful fit: an analysis in upright position
MRI studies have shown what this looks like from the inside. At rest, the pessary sits behind and below the pubic bone, propping up both the front and back vaginal walls. When a person strains or bears down, the pessary moves downward along with the pelvic floor, and this movement tracks very closely with the widening of the pelvic opening.9PubMed Central. Automated Motion Tracking of Vaginal Pessaries and Pelvic Floor Structures on Dynamic MRI This is why fitting matters so much: a device that is the right diameter wedges itself between the pelvic walls snugly enough to resist slipping out during coughing, lifting, or exercise, but not so tightly that it presses painfully against tissue.
Pessaries and Sexual Activity
One of the first questions many people have is whether they can have sex with a pessary in place, and the answer depends almost entirely on the shape. Ring pessaries, including rings with support, can usually be left in during intercourse. The ring sits high enough in the vagina that it does not necessarily interfere, though some couples notice it and some do not. Space-filling pessaries like the Gellhorn, cube, and doughnut need to come out beforehand because they occupy too much of the vaginal canal.2PubMed Central. Sexual Function and Pessary Management Among Women Using a Pessary for Pelvic Floor Disorders
For people who are sexually active and want minimal disruption, this is often a reason clinicians try a ring first. If the prolapse is too advanced for a ring to stay in place, some people learn to remove and reinsert a Gellhorn or cube themselves, treating it more like a removable device they put in during the day and take out at night or before sex. Self-management of this kind does take some dexterity and practice, but many people get comfortable with it over time.
The Arabin Cervical Pessary
Not all pessaries are used for prolapse. The Arabin pessary is a specialized silicone device used during pregnancy to help prevent preterm birth in people with a short cervix. It looks quite different from the pelvic-floor pessaries described above. The Arabin is a perforated dish or shallow cup with a wider outer diameter and a smaller inner opening. It fits around the cervix and tilts it backward, changing the angle at which the weight of the growing uterus presses down.10PubMed Central. The Arabin pessary to prevent preterm birth in women with a twin pregnancy and a short cervix: the STOPPIT 2 RCT
The Arabin comes in a small range of sizes. In one large trial, clinicians chose from three options based on whether the person had given birth before and how the pessary sat once placed: two had an outer diameter of 65 or 70 mm with a 32 mm inner opening, and a third measured 70 mm with a 35 mm inner opening.11JAMA. Cervical Pessary for Prevention of Preterm Birth in Individuals With a Short Cervix: The TOPS Randomized Clinical Trial The device can be placed in a clinic without anesthesia, though it can cause discomfort during insertion. It stays in until about 36 to 37 weeks of pregnancy.
Biofilm, Cleaning, and Long-Term Wear
Any device that sits inside the body for weeks or months will accumulate bacteria. Scanning electron microscopy of used ring pessaries confirmed that biofilm, a structured community of bacteria embedded in a protective slime layer, formed on every single pessary examined in one study. Roughly 40 percent of those pessaries had a biofilm dominated by lactobacilli (the “healthy” vaginal bacteria), while 60 percent had shifted toward communities with more anaerobic bacteria.12PubMed. Bacterial biofilm formation on vaginal ring pessaries used for pelvic organ prolapse
This does not mean pessaries are inherently dangerous, but it does explain why regular cleaning matters. People who manage their own pessary typically remove it every night or every few days, wash it with mild soap and water, and reinsert it. Those who rely on clinic visits for management usually have the device removed and cleaned every three to six months. Postmenopausal people who use a pessary are sometimes prescribed vaginal estrogen alongside it. The estrogen helps maintain the thickness and resilience of the vaginal lining, and a systematic review found it lowered the odds of bacterial vaginosis in pessary users by about 70 percent, though it did not significantly reduce vaginal ulceration or bleeding.13PubMed. Effect of estrogen on vaginal complications of pessary use: a systematic review and meta-analysis
Custom and 3D-Printed Pessaries
Standard pessaries work well for most people, but vaginal anatomy varies widely, and a handful of fixed sizes do not fit everyone. Researchers have begun 3D-printing pessaries from medical-grade silicone, tailored to an individual’s measurements. A pilot study used silicone with a specific firmness rating and tensile strength designed to give the printed pessary adequate mechanical durability while still being soft enough for comfortable wear.14PubMed Central. Tailor-made three-dimensional printing vaginal pessary to treat pelvic organ prolapse: a pilot study The idea is that a scan of the vaginal canal could generate a pessary shape matched precisely to that person’s anatomy, potentially improving comfort and reducing the trial-and-error of traditional fitting.
Custom printing is still in early stages and is not widely available, but it points toward where pessary design is headed. A recurring frustration in pessary care is the iterative fitting process, with different sizes tried and sometimes multiple office visits needed. If imaging and printing technology matures enough, the fitting appointment of the future might produce a device on the spot.
Pessaries Compared With Surgery
Many people first encounter pessaries when they are deciding between conservative management and surgical repair for prolapse. A large prospective study followed women who chose either a pessary or surgery and found that after two years, about 74 percent of the pessary group reported improvement in their symptoms, compared with about 84 percent in the surgery group. Both groups experienced meaningful reductions in symptom severity.15PubMed Central. Pessary or surgery for a symptomatic pelvic organ prolapse: the PEOPLE study, a multicentre prospective cohort study Roughly a quarter of the pessary group eventually switched to surgery, while about one in ten in the surgery group needed additional procedures.
A smaller study found a similar pattern at 12 months: symptom scores were low in both groups, but about 28 percent of pessary users went on to have surgery, compared with only 3 percent needing reoperation in the surgery group.16PubMed Central. Primary treatment of pelvic organ prolapse: pessary use versus prolapse surgery The takeaway is not that one option is clearly better, but that a pessary can be a reasonable first step. It is reversible, does not carry surgical risks, and works well enough for the majority of people who try it. For those who find it insufficient, surgery remains available.
Who Ends Up With Which Shape
The choice between a ring, a Gellhorn, a cube, or another design is not just about the severity of prolapse. Functional factors play a real role. A retrospective study found stark differences between people who could manage their own pessary removal and reinsertion versus those who relied on a clinician. Self-managing users were far more likely to be physically active, sexually active, and to have good hand function and eyesight. Those who needed clinic-based management were more likely to have reduced mobility or weakened hand function.17PubMed Central. Demographic, socioeconomic and functional health-related factors in the selection of vaginal pessaries used for the conservative treatment of pelvic organ prolapse: a retrospective study
In practical terms, a person with arthritis who cannot easily reach inside the vagina to grip and remove a device is probably not going to thrive with a cube pessary that requires nightly removal. She may do better with a ring that a clinician replaces every few months. Conversely, a younger, active person who wants to remove the device for exercise or sex may prefer a Gellhorn or cube she can manage herself. The “right” pessary shape is as much about the person’s daily life, hand dexterity, and preferences as it is about the anatomy of their prolapse.