Suture methods

You will have to suture two kinds of wound: (1) Those caused by trauma, which are described in Chapter 54. (2) Those which you make yourself when you operate. You can sew up both in much the same way. Here, we are mostly concerned with the skin, the special sutures for other structures are described elsewhere[md]arteries (55.6), nerves (55.9), tendons (55.11), the scalp (63.6), and the gut (9.3).

''Over-and-over' sutures are the most common ones, and can be continuous (A, Fig. 4-7) or interrupted (B). Each interrupted suture needs its own knot; each knot can act as a nidus for infection; and each takes time to tie. So continuous sutures are quicker, but they are also less reliable, because, if the knot on a continuous suture unties, or the suture breaks, the whole wound may open up, whereas the loss of a single interrupted suture matters little. A beginner usually finds interrupted sutures easier. If you wish, you can lock a continuous skin suture to make it more secure; you can lock every stitch (G, Fig. 4-7), or every few stitches.

Vertical mattress sutures (C, Fig. 4-7) take a superficial bite to bring the skin edges together, and a deeper one to close the deeper tissues; so they are useful for deeper wounds, but they leave scars: they are always interrupted. Horizontal mattress sutures may be interrupted (D) or continuous, superficial or buried (E), and are merely alternatives to ''over- and-over' sutures without any special merit, except that they are better at everting the skin edges.

A subcuticular suture brings the skin edges together accurately, and is particularly useful in plastic surgery. It can be interrupted (F, Fig. 4-7) or continuous (I, and J, Fig. 61-2). If it is continuous, both ends have to be anchored, either with a button, or with split lead shot clamped to the suture.

G, and H, in Fig. 4-8 show a simple mattress suture contrasted with a figure of eight suture. Use this to stop bleeding from soft bulky tissue when there is no obvious vessel to tie. This sometimes happens when you have closed the uterus after Caesarean section with the usual two layers of sutures and the wound is still bleeding at one end[md]put a figure of eight suture through it.

Fig. 4-8 SOME OF THE BASICS. A, a sponge holder grasping a swab (''a swab on a stick') can be a useful instrument for dissecting delicate structures, as when separating the peritoneum from the vagus nerves (Fig. 11-4). B, as well as cutting with scissors you can push them into the tissues and then gently open them to spread structures apart. This is the ''push and spread technique'. Be gentle! It is useful for tissue planes, but forceful spreading can injure thin walled structures, such as veins. C, a ''reef' or ''square' knot. D, a ''granny knot' which does not hold so well. E, a surgeon's knot for monofilament has three hitches (or ''throws') with two turns (or more) on the first two hitches and one turn on the third. F, a surgeon's knot with multifilament is less likely to slip and need only have a single turn on each of the three hitches. Note that each hitch should ideally make a reef knot with the previous one. G, a mattress suture. H, a ''figure of eight' suture, which is like a mattress suture, except that the needle is inserted in the same direction both times.

KNOTS AND SUTURES SUTURING. Hold a straight needle in your hand. Hold a curved one in a holder about 2/5ths of its length from the eye.

You will also have to hold the tissue you are sewing. Hold a hollow viscus, such as stomach or gut, with plain forceps; hold skin or fascia with toothed ones. If the needle is curved, move the holder through an arc, so as to follow its curve.

In the skin, insert the needle about 5 mm from the edge of the wound, and place sutures about 5 mm apart. Include an equal amount of skin on each side of the wound.

Set knots down so that they lie square, and don't tie them too tight[md]just tight enough to bring the skin edges together. The skin will swell during the following day, and if the knots are already tight, they will become even tighter and impair the circulation, leading to necrosis.

CAUTION ! (1) Don't insert the needle at different depths, or the edges of the wound will overlap. (2) Don't leave dead spaces, or they will fill with fluid which may become infected. (3) Suture towards you. (3) When you suture two tissues together, one of them may be mobile and the other fixed (because you are holding it). Suture from the mobile tissue towards the fixed one. (4) Continue in the curve of the needle.

KNOTS. Tie reef (square) knots, not ''granny knots'. These are both made from two half hitches[md]in a reef knot they go in opposite directions, in a granny knot they go in the same direction. Pull equally on both ends, pull horizontally, and watch the knot go down. If one end is tense and the other loose, you will get a slip or sliding knot.

A surgeon's knot is merely a reef knot with a third half hitch in the same direction as the first one. This third half hitch makes the knot less likely to undo. Some surgeons tie three hitches in all suture materials.

Some suture materials undo more easily than others. Non- absorbable multifilament makes the safest knots. Knots in catgut seldom undo, but knots in monofilament undo much more easily. So always use a surgeon's knot when you tie monofilament. For important knots put two (or more) turns on the first and second hitches. With multifilament a single turn is enough on each hitch.

Practise these knots with string or your shoelaces, until you can do them quickly, and do them blind. Learn the various ways of doing them in the following order.

REEF KNOTS can be tied in several ways. The first method, as in Fig. 4-9, is the surest way of tying a knot and is the one to use if you want to exert continuous pressure while you tie. In the second method, Fig. 4-10, use forceps in your right hand. The third, Fig. 4-11, is an ''instrument tie' and is useful if one end of a suture is short, or if the knot is in a deep cavity. The short end can be quite short. First, make a loop with the instrument in front of the long end. Grasp the short end and pull it through this loop. Then pull the first half hitch tight in the plane of the knot. To make the second half hitch, start with the instrument behind the long end.

TO CUT A SUTURE almost close the scissors, slip their open ends over the suture material, and move them gently down towards the knot. Twist the tip to give you the length of tail you want, then cut. Cut the tails of interrupted skin sutures short enough to prevent them tangling in the next suture. Leave buried catgut sutures with 5 mm tails. Cut buried sutures close beside the surgeon's knot.

CAUTION ! Keep the tips of the scissors in view, and don't cut unless you can see what you are cutting.

Fig. 4-9 TYING A REEF KNOT[md]FIRST METHOD. This is the standard method without using instruments. The difficult steps are C, and D, in which you grasp one of the ends between your middle and ring fingers, and I, and J, where you do the same again.

Fig. 4-10 TYING A REEF KNOT[md]SECOND METHOD. This method is smiliar to the last one except that you are using forceps in your right hand. Use it if you are working in a hole.

REMOVING SUTURES. Leave them until the wound has healed properly. Some sutures can be removed on the 4th day, others not until the 14th. Here is a guide:

The tongue 4 days.

Skin sutures on the face and eyelids 4 days.

The scalp 6 to 7 days.

The hand and fingers 7 days.

The scrotum 5 days.

The abdomen: transverse incision 7 to 9 days, vertical incision 9 to 11 days.

The skin of the back over the shoulders 11 to 12 days.

Retention sutures 10 to 14 days (9.13).

When you remove a suture, try not to pull any part of the suture material which has been on the surface through the tissues, or you may contaminate the wound. Clean the skin, cut the suture where it dips under the skin, and pull it in such a way that it brings the edges of the wound together, as in Fig 54- 8.

Fig. 4-11 TYING A REEF KNOT[md]THIRD METHOD. If there is not enough room for your fingers, use forceps in each hand. This is an ''instrument tie'. Notice that for the first half hitch the instrument is in front of the long end (A), and for the second one it is behind (D). In this way you will tie a reef knot, not a granny knot.