Chromic Catgut Sutures: Different Sizes, Indication, and Contraindication

Surgical sutures can be plain or chromic. Chromic catgut sutures are absorbable sterile surgical sutures made by twisting together strands of purified connective tissue (mostly collagen), derived from the serosal layer of bovine intestines (sheep and goat). They have twisted multifilament structure with a monofilament appearance.

The sutures are treated with chromic salt solution. The chromic salt is to enhance the absorption and also reduce the adverse reaction.

Chromic catgut sutures are also packaged dry or in a solution of 89% isopropanol, 10% water and 1% triethanolmaine. Mild chromic sutures are specially treated for ophthalmic and cuticular applications. The sterilization of the catgut is achieved with EO (ethylene oxide) and gamma radiation.

In the application of the suture, chromic catgut sutures will cause a minimal acute inflammatory reaction in tissues, characteristic of foreign body response to a substance. This is followed by the suture gradually losing the tensile strength and mass due to enzymatic dissolution of the catgut as it absorbed completely. The absorption process is through phagocytosis.

The absorption is not as predictable as in synthetic sutures, but tends to absorb faster on infected wounds. The enzymatic dissolution is similar to the digestion of an animal protein by the body.

After enzymatic hydrolysis, the chromic catgut starts loosing tensile strength about 18 to 21 days of implantation. It retains about 50% of the initial tensile strength after 21 – 28 days of implantation but is completely absorbed within 90 days.

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The rate of the loss of the tensile strength of the suture depends on the type of the suture, site of the tissue and presence of infection.

A unique feature of the chromic catgut suture is the ability to join and regenerate tissues rapidly.


A good chromic catgut suture material should ensure:

  • Non-adhering and biologically inert.
  • The collagen should be pure to ensure optimal tensile strength, and performance
  • The chromic salt treatment should be uniformed to ensure strength and absorption of the suture
  • Surface smoothness to facilitate not run-down and knot strength, as a result of the electronic polishing of each strand
  • Chromic treatment salt should delay the absorption
  • Resistant to tissue liquid enzymes
  • The needle must be sharp enough to enhance smooth riding on tissue during suturing.
  • The chromic catgut must be sterile and cause only minimal tissue reaction during absorption

Clinical Uses of Chromic Catgut Suture

The suture is used in general closure, soft tissue approximation, fast healing tissue and muscles, and in ligation, like ophthalmic surgery, gastrointestinal tract surgery, obstetrics/gynecology.

Just as other absorbable suture material, supplemental non-absorbable sutures should be used as a follow-up for the management of contaminated or infected wounds.

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The suture material is a collagen based material, and is also treated with chromic salt solutions. It is therefore contraindicated in patients with known sensitivities or allergies to collagen or chromium, as it may cause immune reaction.

They are not used in cardiovascular or neurological surgery.

Caution should be applied in using absorbable sutures in region of the body with poor blood supply, as there could be incidence of suture extrusion and delayed absorption.

Different Sizes of Chromic Catgut Suture

The absorbable suture is available in EP and USP sizes 2 (6 metric) through 7-0 (0.7 metric) — USP 6/0 (0.7 Metric), USP 5/0 (1 Metric), USP 4/0 (1.5 Metric), USP 3/0 (2 Metric), USP 2/0 (3 Metric), USP 0 (3.5 Metric), USP 1 (4 Metric), USP 2 (5 Metric), USP 3 (6 Metric)

They can come without needles or with stainless steel needle types like heavy, round body, double armed, or reverse cutting. The suture length can come in different lengths ranging from 75 cm, 100 cm, 150 cm, while the needle length can be 12 mm, 16 mm, 20 mm, 22 mm, 30 mm, 36 mm, 40 mm, 45 mm, 50 mm.

Chrome Catgut is colored brown with pyrogallol, but can also come in indigo color.

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