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Chromic gut suture is made of purified connective tissue, mostly collagen, taken from the intestines of cattle or sheep, and then processed so it resists absorption longer than plain gut. Despite the name “catgut”, no cats are involved. This guide is for clinic staff, buyers and students who need to know what the material is, how plain and chromic gut differ, and where the official definitions come from.
This page describes products and general use; it is not medical advice.
What chromic gut suture is (and why it is called catgut)
Chromic gut is one of the two forms of surgical gut suture, an absorbable, sterile thread that the body gradually breaks down. The older trade word “catgut” survives in product names and search terms, and the device nomenclature still uses it: the Global Medical Device Nomenclature term in FDA’s AccessGUDID database for one chromic gut product is “Catgut suture, chromic”. The material itself comes from cattle (bovine) or sheep (ovine). In practice, “catgut suture”, “surgical gut suture” and “chromic gut suture” refer to the same family of products. For the broader picture of what a suture is, see what a suture is.
Who uses it: surgical and procedural clinicians who close soft tissue, and the staff who stock and buy wound-closure supplies.
What chromic gut suture is made of
FDA’s classification regulation, 21 CFR 878.4830, describes an absorbable surgical gut suture, “both plain and chromic”, as an absorbable, sterile, flexible thread prepared from either the serosal connective tissue layer of beef (bovine) or the submucosal fibrous tissue of sheep (ovine) intestine, intended for soft tissue approximation. J&J MedTech describes its chromic gut product in matching terms: purified connective tissue, mostly collagen, from the serosal layer of beef or the submucosal fibrous layer of sheep intestines.
The GMDN definition attached to a chromic gut record in AccessGUDID calls the thread a single-strand (monofilament), natural, bioabsorbable thread composed mostly of collagen fibres derived from mammals, and describes it as impregnated with chromium salts to increase tensile strength and retard absorption. That record also lists the product as packaged sterile and not requiring sterilization before use.
Plain gut vs chromic gut
Surgical gut sutures are available in plain or chromic. Both start from the same kind of collagen-rich intestinal tissue. The difference is processing: chromic gut is processed to provide greater resistance to absorption.
| Feature | Plain gut | Chromic gut | Source |
|---|---|---|---|
| Starting material | Bovine serosal or ovine submucosal intestinal connective tissue | Same | 21 CFR 878.4830 |
| Main component | Purified connective tissue, mostly collagen | Same | J&J MedTech product page |
| Added processing | None named in the sources | Processed for greater resistance to absorption (chromium-salt impregnation to retard absorption in the GMDN definition) | J&J MedTech; AccessGUDID |
| FDA classification | Class II, covered by 878.4830 | Class II, covered by 878.4830 | 21 CFR 878.4830 |
How FDA regulates gut suture
Under 21 CFR 878.4830, absorbable surgical gut suture is a Class II device, with the special controls guidance “Surgical Sutures” applying. Plain and chromic gut share a single regulation, so neither is treated as a different device type by FDA. Class II means the product is subject to special controls beyond general controls; it says nothing about which gut suture suits a given procedure.
Uses
The regulation states the intended use in one phrase: soft tissue approximation. Anything more specific, including which tissues, which size and how long the suture should last, belongs to the manufacturer’s instructions for use (the package insert) and to the treating clinician. The J&J MedTech product page likewise points readers to the full package insert rather than listing indications.
Size labels
Suture size is printed on the package. In the AccessGUDID record cited here, the size text reads “USP 0 EP 4”, showing that labels can carry both a United States Pharmacopeia (USP) size and a European Pharmacopoeia (EP) size. Treat that as one product’s label, not a conversion chart: use the size chart in the manufacturer’s package insert for the product in hand.
Safe handling basics
- Gut suture is supplied sterile; the AccessGUDID record lists it as a single-use device, packaged sterile. For how sterile supplies are categorised, see sterile versus non-sterile supply.
- Read the package insert before use. It, not a general web page, is the authority on handling, storage and contraindications for a specific product.
- Remember that this material is of animal origin; check the product label and insert for any related warnings.
Common mistakes
- Assuming “catgut” means cat intestine. The regulation names cattle and sheep.
- Treating plain and chromic as interchangeable. They share a source tissue but differ in resistance to absorption.
- Reading a USP size and an EP size as the same number. A label such as “USP 0 EP 4” shows two different scales.
- Confusing absorbable with non-absorbable. It is a product property; see absorbable vs non-absorbable sutures.
FAQ
What is chromic gut suture made of?
Purified connective tissue, mostly collagen, from the serosal layer of bovine intestine or the submucosal layer of ovine intestine, processed for greater resistance to absorption.
What is catgut suture made of?
The same material: bovine or ovine intestinal connective tissue. “Catgut” is a historical name, not a source animal.
What is plain gut suture made of?
The same collagen-rich intestinal tissue as chromic gut, without the added processing that gives chromic gut greater resistance to absorption.
What are catgut suture sizes and types?
The two types are plain and chromic. Sizes are set by the manufacturer and printed on the package, for example “USP 0 EP 4” on one AccessGUDID record; use the package insert’s size chart.
What are chromic and plain gut suture used for?
FDA describes the intended use as soft tissue approximation. Specific indications come from the package insert and the clinician.
For other suture types, lac.us lists braided sutures in its surgical and procedural range; gut sutures are monofilament, so that category covers different products. See also what a medical device is.
Sources (checked 2026-10-30)
- FDA, 21 CFR 878.4830, Absorbable surgical gut suture: https://www.ecfr.gov/current/title-21/chapter-I/subchapter-H/part-878/subpart-E/section-878.4830
- NLM AccessGUDID device record, chromic gut suture: https://accessgudid.nlm.nih.gov/devices/07500142000270
- J&J MedTech, Surgical Gut Suture, Chromic: https://www.jnjmedtech.com/en-US/product/surgical-gut-suture-chromic
