There are a number of suture materials available, but it is beyond the scope of this module to cover them in any detail. In selecting a particular suture, the physician needs to consider the physical and biological characteristics of the material in relation to the healing process.

Suture materials can be broadly categorized as absorbable and non-absorbable. Absorbable sutures do not require removal as they are digested by tissue enzymes. Non-absorbable or permanent sutures need to be removed at a later date.

Absorbable sutures can be further divided into rapidly absorbing (days) and slowly absorbing (months). The choice will depend on the rate at which the particular tissue regains its strength. Fortunately, the choice is often not an issue in the Emergency Department because most wounds encountered there require support for a matter of days to weeks. Sutures available in the Emergency Department will meet this requirement.

Both absorbable and non-absorbable sutures are graded for size or diameter of the strand. The grading system uses the letter O and the number of stated O's indicates the size. The more O's, the smaller the size. For example, a 6-O is smaller than a 4-O. Accordingly, tensile strength of a particular suture type increases as the number of O's decreases.

The needles supplied with sutures also have important features. In general, for Emergency Department use, needles are either large or small and either cutting or non-cutting. Large needles have the advantage of closing a deeper layer of tissue with each "bite". The concern with small needles is that there will be inadequate closure of deep subcutaneous tissues, leaving potential space for hematoma formation. However, small needles create smaller puncture wounds and may have the advantage of reducing scarring

Cutting needles have at least two opposing cutting edges to facilitate passage through tough tissue. These needles are used for skin closure. Non-cutting or tapered needles are used to close subcutaneous tissue, muscle and fascia. They have sharp points, but do not have cutting edges.