Ring Pessary Sizes 0–9 Explained: Diameters, How to Choose, and What Each Size Treats

If your gynecologist recommended a pessary, the next question is which size. Ring pessaries are sized 0 to 9 — ten sizes, with diameters from 44 mm (1.75 inches) to 102 mm (4 inches). This guide walks through every size: exact dimensions, when each is typically prescribed, the three most common sizes that cover most patients, and what to do if you're between two sizes.

Quick answer: The three most-prescribed ring pessary sizes are 3 (64 mm), 4 (70 mm), and 5 (76 mm), which together fit the majority of patients. SciMed offers ring pessary sizes 0–8 with support and sizes 0–9 without support, all FDA 510(k) cleared, from $49.99 each. If you're uncertain between two sizes, the 2-size Combo Pack ($89.99) lets you trial both.

Complete ring pessary size chart

Size Diameter (mm) Diameter (inches) Typical use Frequency
0 44 mm 1.75″ Small-framed patients, mild prolapse Less common
1 51 mm 2.00″ Light support, smaller anatomy Less common
2 57 mm 2.25″ Average frame, mild-moderate POP Common
3 64 mm 2.50″ Most common fitting size Most common
4 70 mm 2.75″ Most common fitting size Most common
5 76 mm 3.00″ Common, fits larger anatomy Most common
6 83 mm 3.25″ Larger frame or significant laxity Common
7 89 mm 3.50″ Post-surgical or marked laxity Less common
8 95 mm 3.75″ Largest with-support size Less common
9 102 mm 4.00″ Without-support only — largest available Uncommon

Sizes 3, 4, and 5 (highlighted) fit approximately 60–70% of patients in clinical practice. If you've never been measured, your clinician will likely start with one of these three.

How clinicians measure for pessary size

Pessary sizing is done by a clinician during a pelvic examination. The exam follows a standard sequence:

  1. Vaginal-width measurement using the clinician's fingers from the posterior fornix to behind the pubic bone. This distance correlates roughly to ring diameter.
  2. Trial fitting with a ring pessary of an estimated size from a fitting kit. The clinician inserts the device and asks you to stand, walk, bear down, and sometimes cough.
  3. Adjustment if the ring slips during bearing down (size too small) or causes discomfort (size too large).
  4. Final confirmation: the correct-sized pessary stays in place during all activities and is comfortable.
Clinical practices use a 7-size Clinical Fitting Kit for in-office sizing — 7 ring pessaries covering sizes 1–7 (51–89 mm), the range that fits ~95% of patients. Devices are autoclavable for re-use between patients.

What each size typically treats

Sizes 0–1 (44–51 mm)

The smallest sizes. Typically used for small-framed patients, post-partum prolapse in younger patients, or as a starting size when anatomy is on the smaller end.

Size 2 (57 mm)

The smallest of the "common" range. Fits patients with mild to moderate pelvic organ prolapse and average-to-small anatomy.

Sizes 3–5 (64–76 mm) — the workhorses

These three sizes fit the majority of patients. Most clinicians starting a new pessary fitting trial size 4 first — the size that fits typical adult anatomy with moderate prolapse.

Sizes 6–7 (83–89 mm)

Larger sizes for patients with larger frames or more significant vaginal-vault laxity. Also commonly used post-hysterectomy when the vaginal vault has expanded.

Size 8 (95 mm)

The largest with-support pessary size. Used for marked laxity or post-surgical anatomy where smaller sizes won't stay seated.

Size 9 (102 mm) — without support only

The largest available ring pessary, sold without support membrane only. Used for the most marked vaginal-vault laxity, often post-hysterectomy with significant descent.

What if I'm between two sizes?

Between-sizes is common. Options:

  1. Try the larger size with care. Sometimes a slightly larger ring needs 1–2 weeks of break-in before feeling normal.
  2. Try the smaller size with support. A size 3 with support membrane fits differently than a size 3 without — the membrane can stabilize a ring that would otherwise slip.
  3. Buy a 2-size combo pack and trial both. SciMed's Combo Pack ($89.99) includes two adjacent sizes — cheaper than two singles.
  4. Ask your provider about a different style. If neither adjacent ring size fits, a different pessary type (Gellhorn, donut, or cube) may be more appropriate.

What sizes SciMed offers

Type Sizes available Price
Ring Pessary With Support (for POP + bladder support) 0–8 (44–95 mm) $49.99
Ring Pessary Without Support (for POP only) 0–9 (44–102 mm) $49.99
Combo Pack — 2 adjacent sizes Pick any 2 consecutive sizes $89.99 (~10% off)
Right-Size Pack — 3 adjacent sizes Pick any 3 consecutive sizes $129.99 (~13% off)
Clinical Fitting Kit — sizes 1–7 for OB-GYN practices 1–7 (51–89 mm) From $289.99
FDA 510(k) cleared · OB-GYN approved · Doctor recommended
Free US shipping · Same-day dispatch from California.
Shop SciMed pessaries by size →

FAQ

What is the most common ring pessary size?

Sizes 3, 4, and 5 (64–76 mm) are the most-prescribed. Size 4 is often the starting point for a new fitting.

What does "size 4" mean in mm?

Size 4 ring pessary has a 70 mm outer diameter (2.75 inches). Sizing is standardized across major manufacturers (Milex, Bioteque, SciMed).

Is the SciMed sizing the same as Milex sizing?

Yes. Ring pessary sizing is standardized: size 3 is 64 mm, size 4 is 70 mm, etc., across all FDA-cleared manufacturers.

Can I order without being fitted by a clinician?

Pessaries can be ordered without a prescription in the United States. However, for first-time use, a clinical fitting is strongly recommended. If you can't get in-clinic, a 2-size or 3-size combo pack lets you trial multiple sizes at home.

What if my pessary worked at size 4 last year and now it's loose?

Size change usually signals an anatomy change — weight loss/gain of 15+ lbs, menopause transition, starting vaginal estrogen, or post-surgical changes can shift fit. See your provider for refitting.

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