09.05 Suturing Techniques - Subcuticular Sutures
Inserting each suture correctly is the key to good wound closure. Here you will learn how to place a suture and how to avoid damage to the wound edges.
You should be familiar with how to use the needle holder and suture needle to insert a suture with minimal tissue damage.
This module covers simple interrupted, continuous, subcuticular, mattress and pulley sutures and has plenty of tips on how to overcome common problems.
In this module
09.05 Subcuticular Sutures
A single unbroken suture snakes to and fro in the subcuticular plane, parallel to the skin surface. This closure relies on suture friction and can only be used on straight or slightly curved wounds where there is minimal wound tension.
It is not suitable for wounds where the skin edges are irregular, unequal lengths, or ragged and traumatised.
Absorbable braided (multifilament) sutures are usually used for subcuticular closure because they do not need to be removed and are gradually absorbed. They also have more friction than monofilament sutures and so do not gape easily.
09.05.01 Principles Video 1
Before you can practise this technique, you must be able to identify the subcuticular plane. This glistening layer lies between the skin and the subcutaneous fat. The needle is guided in through the skin, a short distance from the end of the wound, and emerges in the subcuticular plane.
The free end of the suture is grasped with artery forceps to stop it pulling through.
09.05.02 Principles Video 2
The needle is held parallel to the surface of the skin and stays in this plane throughout the closure. The needle follows the path of its curvature and care must be taken not to traumatise the wound edge. Each new bite starts at a point exactly opposite the place where the previous bite emerged, so that the closure is regular and symmetrical.
The suture should be left loose as the closure progresses, with the wound edges separated. This makes it easier to see what you are doing and to make adjustments as you go.
When the end of the wound is reached, the needle is brought out through the skin at a little distance from the wound.
Gently pulling both ends of the suture will draw the wound edges snugly together. A steri strip can be used to secure each suture end.
09.05.03 Principles Video 3
Most subcuticular closures are now performed using absorbable sutures that are not removed, and a buried knot technique rather than steri-strips to secure each end. When starting the suture line, the first bite goes deep into the subcutaneous tissue and then a second bite is taken back to the starting position. A standard surgeon’s knot is tied and the short end is cut as close as possible to the knot.
To secure the other end of the suture line, a short loop is left when pulling through the last suture and a surgeon’s knot is tied using the loop as a substitute for the free end. The looped end is then cut as close as possible to the knot and the long end is taken down through the subcutaneous tissue and emerges beyond the end of the wound. Now this long end is cut flush with the skin. The finished result is a wound with no visible knots.
09.05.04 Principles Video 4
Some surgeons prefer to use a hand held straight needle and an absorbable suture for subcuticular closure, since it is quicker and therefore more suited to larger incisions. However, this technique requires great care because of the higher risk of needlestick injury.
In this demonstration the surgeon is using a 60mm reverse cutting hand held straight needle with a 3/0 undyed vicryl suture. The needle is inserted a long way from the wound edge in the subcuticular plane and emerges right in the corner of the wound. The closure then proceeds with a series of horizontal, looping bites in the subcuticular plane. Tension is adjusted as required and then the needle is taken out along the subcuticular plane, emerging through the skin at some distance from the end of the incision. Both suture ends are then cut flush with the skin.
09.05.05 Practise
Guide the needle in through the skin a little way from the start of the incision and emerge in the subcuticular plane. Grasp the free end of the suture with the artery forceps to stop it inadvertently pulling through, then reposition the needle in the needle holder.
Hold the needle parallel to the surface of the skin. Take a curved bite in the subcuticular plane, allowing the needle to follow its own curve. Readjust the needle. Start the second bite exactly opposite the place where the needle emerged from the first bite on the other side.
Repeat this process with a series of looping bites along the wound length, all in the subcuticular layer. Always insert and remove the needle along the line of its curvature.
When you reach the end of the wound, bring the needle out through the skin at a little distance from the wound. Gently pull the ends of the suture. The wound should close neatly and remain closed when you let go.
A steri-strip can be used to secure each suture end.
09.05.05.01 Buried Knot Technique
Starting at one end of the wound, insert your first bite deep in the subcutaneous tissue. Reverse your needle and take a second bite back to your starting position. Tie a standard surgeon’s knot then cut the short end as close as possible to the knot.
Now pick up the long end and take a deep bite in the subcutaneous tissue, emerging in the skin at the beginning of the incision. The closure now proceeds with a series of horizontal, looping bites along the wound length, all in the subcuticular layer.
When you reach the end, adjust tension as required before taking a deep bite in the subcutaneous tissue. Pull through leaving a short loop which will act as a substitute for the short end of the suture. Tie a standard surgeon’s knot and cut the short looped end only, as close as possible to the knot. Don’t cut the long end of the suture at this stage.
Now pick up the long end and take a final bite emerging in the skin a short distance beyond the end of the incision. Cut your suture flush with the skin.
The finished result should be a wound with even tension and no visible knots.
09.05.06 Things To Avoid
The next few videos will show examples of common problems with subcuticular closure, together with suggestions for solving them.
09.05.06.01 Buttonholing
If you do not keep the needle parallel to the skin surface while suturing, the needle may come out of the skin and go back in again. This ugly effect is called 'buttonholing'.
09.05.06.02 Incorrect Spacing of Bites
Taking a needle bite which starts nearer to the insertion point of the suture than where the previous bite emerged will make the closure bunch up, causing ugly wrinkles.
Taking a needle bite which is not exactly opposite from where the previous suture emerged will leave a gap in the suture line, with too much room between the bites.
Ensure that each bite starts exactly opposite the point where the previous bite came out.
If you make the bites that run parallel to the skin too long, this will result in too few bites for the overall wound length and will cause gaps when the wound is drawn together.
09.05.06.03 Bite Pulling Out
Too shallow a bite in the subcuticular layer will give inadequate purchase. The needle will pull out of the subcuticular tissue.
Ensure that each bite is deep enough to get a firm purchase in the subcuticular layer.
Take a substantial bite along the curvature of the needle, remaining at the same depth throughout.
09.05.06.04 Suture In Wrong Layer
A suture in the subcutaneous fat is very likely not to hold. It may pull through the fat and come out.
Ensure that you have correctly identified the subcuticular layer. Ensure that your suture bite remains within the subcuticular plane.
09.05.06.05 Suture End Pulling Through
The free end of the suture can pull out as you are inserting the continuous subcuticular suture. To avoid this problem, secure the free end of the suture with artery forceps after entering the subcuticular plane.
When grasping a fine suture with artery forceps, hold the suture so that it runs at right angles to the grooves in the artery forceps' jaws. Failure to do this will allow the suture to slip out.
09.05.06.06 Too Fine A Suture
Too fine a suture will provide inadequate friction to hold the wound together and the edges will gape.
3-0 (2 metric) is suitable for most subcuticular closures.
09.05.06.07 Wound Edge Tension
The wound edges are held together with friction on the suture in the subcuticular layer. The closure will only succeed if there is no significant tension pulling the wound edges apart.
Judicious undermining with a scalpel may be needed in some cases.
Sometimes you may need to insert absorbable sutures in the subcutaneous layer to bring the wound edges together before you attempt the subcuticular closure.
Even with two or three throws you may experience problems with slippage using an instrument-tied knot. Tying your knot by hand will allow you to hold both strands under tension and snug the knot down to alleviate this problem.
The ends of the knot should be cut as short as possible.
If tension is still too great, use interrupted sutures to close the wound instead, and the technique of progressive halving to distribute the tension equally across the wound