How is the simple interrupted suture placed?

Updated: Mar 05, 2020
  • Author: Desiree Ratner, MD; Chief Editor: Dirk M Elston, MD  more...
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Answer

The most commonly used and most versatile suture in cutaneous surgery is the simple interrupted suture. [43] This suture is placed by inserting the needle perpendicular to the epidermis, traversing the epidermis and the full thickness of the dermis, and exiting perpendicular to the epidermis on the opposite side of the wound. The two sides of the stitch should be symmetrically placed in terms of depth and width.

In general, the suture should have a flask-shaped configuration, that is, the stitch should be wider at its base (dermal side) than at its superficial portion (epidermal side). If the stitch encompasses a greater volume of tissue at the base than at its apex, the resulting compression at the base forces the tissue upward and promotes eversion of the wound edges (see the image below). This maneuver decreases the likelihood of creating a depressed scar as the wound retracts during healing.

Simple interrupted suture placement. Bottom right Simple interrupted suture placement. Bottom right image shows a flask-shaped stitch, which maximizes eversion.

As a rule, tissue bites should be evenly placed so that the wound edges meet at the same level; this minimizes the possibility of mismatched wound-edge heights (ie, stepping). However, the size of the bite taken from the two sides of the wound can be deliberately varied by modifying the distance of the needle insertion site from the wound edge, the distance of the needle exit site from the wound edge, and the depth of the bite taken.

The use of differently sized needle bites on each side of the wound can correct preexisting asymmetry in edge thickness or height. Small bites can be used to precisely coapt wound edges. Large bites can be used to reduce wound tension. Proper tension is important to ensure precise wound approximation while preventing tissue strangulation. (See the image below.)

Line of interrupted sutures. Line of interrupted sutures.

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