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Chromic catgut is a fibrous material made from collagen taken from cow or sheep intestines and then treated with chromic acid salts. It is used to make surgical sutures that can be absorbed by the body. Due to its treatment with chromic acid, this type of suture has several benefits that can make it preferable to regular catgut and some other types of sutures. Although catgut and chromic catgut have been replaced in many cases by sutures made of synthetic materials, they are still available and used in some surgeries.
To make chromic catgut, the bovine or ovine intestinal collagen is twisted into strands of varying sizes. These threads are then sterilized so they are suitable for surgery. Finally, a chromium salt solution is applied to infuse the sutures, and the strands are spun electronically to ensure the chromic coating is applied evenly. The resulting sutures are brown in color, making them slightly darker than plain catgut.
All catgut sutures are designed to be absorbed by the body so there is no need to remove them manually. The body’s enzymes gradually dissolve them, making them ideal for certain procedures, particularly those done internally that are not able to be accessed again. Absorption time of chromic catgut is roughly double that of plain catgut, lasting around 90 days or more. This offers a distinct advantage if the sutured area is slow-healing and requires the additional time.
Another advantage of chromic catgut is its tensile strength. Although all catgut is fairly strong, the chromic variety maintains its strength within body tissues two to three times longer than the regular, untreated type. Knots made with chromic catgut are very secure, and since sutures maintain their integrity for a greater period of time, this is another advantage for slower healing incisions.
The surface of a chromic catgut suture is dry and smooth, in comparison to normal catgut, which is wet. This makes it easier to handle when sewing an incision, a plus for the surgeon working with it. This type of surface also allows for a strong, secure knot to be made during stitching, minimizing the risk of knots not staying in place.
Using chromic catgut can also help minimize irritation at the surgical site. The chromic covering causes less of a reaction in the body’s tissues than other non-treated types of sutures do. This leads to less inflammation and faster healing.