Written and maintained by CASRAI Editorial Board
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This page describes products and general use; it is not medical advice.
An introducer sheath is, in U.S. federal regulation, “a sheath used to facilitate placing a catheter through the skin into a vein or artery.” It is a Class II medical device. The part buyers and clinic staff rarely see is how FDA splits the category into two product codes: DYB for the device and OFC for the kit.
Who uses it: clinicians who place vascular catheters, and the clinic staff, buyers and students who need to identify, classify or order the product correctly.
What an introducer sheath is
The U.S. Code of Federal Regulations calls the device a “catheter introducer” and identifies it in 21 CFR 870.1340(a) as “a sheath used to facilitate placing a catheter through the skin into a vein or artery.” Its purpose is therefore to serve as the passage through which another catheter is placed, not to be the catheter that stays in the patient for treatment. Under 21 CFR 870.1340(b) it is classified as Class II (performance standards).
Search results use several names for the same regulatory object: introducer sheath, sheath introducer, catheter introducer and vascular sheath. FDA’s product code name for the device is “introducer, catheter”.
Where it sits among catheter products
Because the sheath exists to help place another catheter, it appears as a component or companion product in other catheter topics. Guides on this site that mention it in that role include what a PICC line is, the central line kit and the Broviac catheter. In each of those the sheath is part of the placement set, and the catheter being placed is the product the page is about.
FDA classification: DYB versus OFC
Both product codes fall under the same regulation, 21 CFR 870.1340, and both are Class II. They differ in what is being sold and in the premarket route.
| FDA product code | FDA device name | Regulation | Class | Premarket and review note |
|---|---|---|---|---|
| DYB | Introducer, catheter | 21 CFR 870.1340 | 2 | Eligible for the 510(k) Third Party Review program; not GMP exempt |
| OFC | Catheter introducer kit | 21 CFR 870.1340 | 2 | Set up under FDA’s 1997 convenience kits interim guidance; under enforcement discretion, so no 510(k) is required if the kit meets all criteria in that guidance; not eligible for Third Party Review; not GMP exempt |
In practice, DYB is the code for the introducer device itself, and OFC is the code FDA created for a packaged kit that includes an introducer.
Safe use and handling basics
Product-specific details such as compatible catheter sizes, flushing and placement technique belong to the manufacturer’s instructions for use for that exact model, and this page does not give procedure steps. Two general points follow from the classification above: an introducer is a regulated Class II device, and a kit is regulated under its own product code, so the labeling and instructions that come with a specific product are the authority for how that product is used.
Common mistakes
- Treating the sheath as the catheter. The regulation defines the sheath as the aid for placing a catheter, so the two are different products with different roles.
- Mixing up the device and the kit. DYB (device) and OFC (kit) are separate FDA product codes with different premarket routes, even though both sit under 21 CFR 870.1340.
- Reading “enforcement discretion” as “unregulated”. For OFC kits, FDA states that no 510(k) is needed only if the kit meets all criteria in the convenience kits guidance, and the code is not GMP exempt.
Frequently asked questions
What is an introducer sheath?
It is a sheath used to facilitate placing a catheter through the skin into a vein or artery (21 CFR 870.1340(a)). FDA lists it as “introducer, catheter” under product code DYB.
What FDA class is an introducer sheath?
Class II (performance standards) under 21 CFR 870.1340(b). Both DYB and OFC are class 2 in FDA’s Product Classification database.
What is the difference between DYB and OFC?
DYB is the introducer device. OFC is the catheter introducer kit, established under FDA’s 1997 convenience kits guidance and under enforcement discretion when the kit meets all criteria in that guidance.
Is an introducer sheath the same as a catheter?
No. The regulation defines the sheath by its job of helping place a catheter.
Related supplies
Medical supply listings for this product class are grouped under introducer sheaths.
Sources
- 21 CFR 870.1340, Catheter introducer, Cornell Legal Information Institute mirror of the eCFR: law.cornell.edu/cfr/text/21/870.1340 (checked 2026-10-31).
- FDA Product Classification, product code DYB: accessdata.fda.gov, ID=DYB (checked 2026-10-31).
- FDA Product Classification, product code OFC: accessdata.fda.gov, ID=OFC (checked 2026-10-31).
- openFDA device classification API, product codes DYB and OFC (GMP exempt flag), open.fda.gov (data last updated 2026-10-19, checked 2026-10-31).
