Suture material and suturing
Sutures and ligatures consist of absorbable or non-absorbable materials. Catgut remains the most popular absorbable material because of its pliability and superior handling qualities. Chromic catgut lasts for 2 or 3 weeks in the tissues and is excellent for ligatures and for approximating tissues, though it is no longer used for closing abdominal wounds and in other situations where prolonged support is needed, because of the rapid loss of tensile strength as it is absorbed. Plain catgut is absorbed in 5-7 days, but is useful when healing is expected within this period, and for suturing the bladder mucosa.
Non-absorbable materials include braided lengths of natural products (such as silk, linen, and cotton) and synthetic monofilaments (such as nylon and polypropamide). Choice among these materials depends on cost, availability, individual preference in handling, security of knots, and the behaviour of the material in the presence of infection.
Suture is a thread like material used to close surgical wounds and unite two edges of cut tissue.
Types of Suture Materials
Suture materials can generally be classified as absorbable and non absorbable.
Absorbable: This is a type of suture material that gets absorbed by the tissue. E.g. Catgut (natural or biologic type) Vicryl (Synthetic)
Non absorbable: This is a type of suture material that remains unabsorbed by the tissue. E.g. Silk (natural or biologic type) Nylon (Synthetic)
Never use thread for sutures deep in a wound that may be contaminated. Monofilament nylon, however, may be left in the deeper layers; it is better used as a continuous stitch, as its knots are less secure than those of thread. All varieties of suture material may be used in the skin. Thread is easier to use for interrupted stitches, while nylon marks the skin least and is convenient for continuous stitches. Use absorbable material in the urinary tract to avoid the encrustation and stone formation associated with non-absorbable sutures.
Selection of suture materials
Different surgical stitches are used in various types of tissues for different purposes. Important factors considered when selecting suture material for surgery include:
- Type and site of the operation
- Healing characteristics of the tissue involved
- Properties of the suture and needle
- Security of knots
- Behavior of the material in presence of infection
- Suture size (The commonest surgical suture size is between 4/0 and 1)
Size and strength of materials
Sutures are graded according to size on two scales: an old system that runs upwards from O to 4 and downwards to about 6/0, and a metric system running from O to 8.
Old: 6/0 5/0 4/0 3/0 2/0 0 1 2 3 4
Metric: 1 1.5 2 2.5 3 4 5 6 7 8
The basic principles of suturing technique include:
- Inserting the needle at right angle and gently advance through the tissue
- Avoiding tension
- Size and interval between bites are dependent on the tissue thickness and type of tissue to be sutured
Forms of suturing techniques
Important types of suturing techniques commonly used include:
- Simple interrupted
- Continuous simple
- Vertical and horizontal mattress
- Subcuticular stitches