Vacuum bell: how to choose the size

By Javier Santana, founder of Pectus Academy · Updated October 2026

Short answer: the size is chosen by age and chest surface. The device described in the Basel studies comes in three diameters (16, 19 and 26 cm), with versions for women and for adults with a small, deep dip. Other manufacturers use different measurements, so you have to go by each one's chart.

What sizes are there?

Those diameters belong to one specific device. They are not a standard: a bell with a different shape may come in S, M and L with its own measurements.

How do I know which size I need?

1. Check the manufacturer's chart. Each one says what to measure. Some size the bell by the distance between the nipples.
2. Check where the center sits. In the published protocol, the middle of the bell's window is placed over the deepest point of the dip.
3. Ask your doctor first. In the Basel series the first application is done in the clinic, with the doctor present. That is a good moment to check the size.

What if I am between two sizes?

We have not found published guidance for that. Ask the manufacturer or the doctor who prescribes it. The published criterion is age and chest surface, and for an adult with a small, deep dip there is the reinforced model.

Does the size change as you grow?

Because it is chosen by age and chest surface, in a growing child or teenager it is worth rechecking at follow-up visits, which in the Basel series take place every 3 to 6 months.

Are there vacuum bells for women?

Yes. The Basel device has an adapted version for teenagers and adult women. In that series, 28 of the 140 patients were female.

Does size affect the result?

We have not found any study comparing sizes. What studies do link to results is the depth of the dip, the flexibility of the chest and the hours and months of use. We cover that in how many hours a day and for how long.

What we know and what we don't

What we know

• The sizes of the device used in the Basel studies and the criterion for choosing them.
• That in that series the first application is done in the clinic.

What we don't know

• Whether size affects the result.
• How sizes from different manufacturers map onto each other.

Before you use one

The Basel studies used their own device, so its sizes do not carry over to other bells. Talk to your doctor before using a vacuum bell: it has contraindications.

The 16-week program includes a module on the bell for those using one with their doctor: how to position it, how to progress and when to stop.

This content is educational and does not replace the advice of a healthcare professional. We do not promise a specific result.

Sources

1. Haecker FM, Sesia S. Vacuum bell therapy. Annals of Cardiothoracic Surgery, 2016. annalscts.com
2. van Braak H, de Beer SA, al Ghouch Y, et al. 15 Years of Vacuum Bell Therapy for Pectus Excavatum: Long-term Outcomes and Influencing Factors. Journal of Pediatric Surgery, 2025;60(2):161891.
3. Scottish Health Technologies Group. Vacuum bell device for the correction of pectus excavatum, June 2, 2025. shtg.scot