Suturing techniques and common surgical procedures

Tissue	Comment	Type
Skin	Non-absorbable	Monofilament / multifilament
Subcuticulis	Absorbable of short duration. Tissue heals quickly as it is not reliant on suture for much more than 14–21 days	Monofilament / multifilament
Fascia	Absorbable of long duration / non-absorbable. Tissue heals slowly and may rely on the strength of a suture for up to 9 months	Monofilament
Muscle	Absorbable of long duration / non-absorbable	Monofilament / multifilament
Hernia repair	Absorbable of long duration / non-absorbable	Monofilament
Viscera	Absorbable of short duration. Tissue heals quickly as it is not reliant on suture for much more than 14–21 days	Monofilament
Tendon	Non-absorbable	Monofilament
Vessel ligation	Absorbable of short duration. A non-absorbable multifilament (e.g. silk) may be used for large vessels (e.g. renal artery or vein)	Multifilament / monofilament
Vessel repair	Non-absorbable	Monofilament
Nerve	Non-absorbable	Monofilament

^*Adapted from Manual of Canine and Feline Surgical Principles. BSAVA. Gloucester.

As a general rule when selecting suture material, consider the following:

• Avoid multifilament material in contaminated wounds – there is a risk of ‘wicking’ and the spaces between the strands may harbour blood, which will become a medium for bacterial growth.

• Avoid non-absorbable materials in hollow organs (e.g. in the bladder the suture may become a focus for deposition of crystals forming calculi).

• Avoid burying any suture material from a multi-use cassette – there may be a risk of contamination from previous use.

• Avoid using catgut in inflamed, infected or acidic wounds – absorption is more rapid in these wounds.

• Avoid reactive materials in the creation of stoma.

• Use slowly absorbable materials in fascia or tendons – the rate of healing is slow and the tissue requires the support of the sutures for some time.

• Use inert material in the skin.

Suture needles

There are many different types of suture needle and the choice depends on:

• Type of tissue to be sutured

• Size of the wound

• Suture pattern

• Type of suture material

• Surgeon’s preference.

Table 10.3 and Figure 10.1 describe the basic components of suture needles.

Table 10.3

Basic components of suture needles

Figure 10.1 (A) Basic components of a needle. (B, C) Needle body shapes and sizes.

Examples of needle holders (Fig. 10.2) include Gillies (which also provides a scissor action but no ratchet), Olsen-Hegar (which has a ratchet and scissor action) and McPhails (which has a spring ratchet). All needles, with the exception of straight ones, should be held in needle holders, which will provide control as the needle is pushed through the tissue and, when using cutting needles, will protect your gloves or fingers.

Figure 10.2 Examples of scissors, needle holders and forceps.

The needle should be grasped by the tips of the needle holder at a point on the needle that is one-third to half of the way along the needle from the suture material end. If the tissue is delicate you hold the needle closer to the suture material end, and closer to the point for tougher tissues.

Interrupted cruciate suture – this is currently a popular type of suture formed by two linked simple sutures arranged as a figure-of-eight and tied with one knot (Fig. 10.4). The advantages are that there are fewer knots, making it quicker to place, and the tension is spread better over a larger area than it is with a simple suture. Remove by cutting both loops so that you avoid dragging pieces of the suture that have been exposed to the external environment through the tissues.

Figure 10.4 Interrupted cruciate suture pattern. (Reproduced with permission from Stephen Baines, Vicky Lipscomb and Tim Hutchinson: BSAVA Canine and Feline Surgical Principles, 2012, originally illustrated by Samantha J Elmhurst.)

Procedure: Horizontal mattress suture

This is an everting suture.

1. Action: Holding the needle with needle holders, insert it into the tissue on the far side of the incision about 2–5 mm away from the edge. Pass across the incision and bring the needle up on the near side (Fig. 10.5).

Figure 10.5 Horizontal mattress suture pattern. (Reproduced with permission from Stephen Baines, Vicky Lipscomb and Tim Hutchinson: BSAVA Canine and Feline Surgical Principles, 2012, originally illustrated by Samantha J Elmhurst.)

Rationale: This is the same as for a simple suture. The suture should be placed just below the dermis.

2. Action: Move about 6–8 mm along the incision and reinsert the needle into the tissue on the near side.

Rationale: The suture material has made a horizontal line parallel to the edge of the wound (Fig. 10.5).

3. Action: Pass across the incision and bring the needle up on the far side.

The suture material has described a rectangle across the incision (Fig. 10.5).

4. Action: Draw the suture material moderately tight so that the edges appose and then tie a knot.

Rationale: Do not pull so tight that the edges evert.

5. Action: Repeat the process for the next suture, which should be about 4–5 mm away.

Rationale: This type of suture can be used in areas of tension as the pressure exerted by the horizontal sutures is spread evenly over a broad area, which reduces the likelihood of tearing through the tissue edges.

Procedure: Vertical mattress suture

This is a tension-relieving suture.

1. Action: Holding the needle with needle holders, insert the needle approximately 8–10 mm away from the edge of the incision on the far side (Fig. 10.6).

Figure 10.6 Vertical mattress suture pattern. (Reproduced with permission from Stephen Baines, Vicky Lipscomb and Tim Hutchinson: BSAVA Canine and Feline Surgical Principles, 2012, originally illustrated by Samantha J Elmhurst.)

Rationale: This will leave enough space to complete a stitch that is at right angles to the incision line. If you insert the needle too close there will not be enough room to complete the manoeuvre correctly.

2. Action: Pass through the incision line and bring the needle up at an equal distance on the near side (Fig. 10.6).

Rationale: This is for the same reason as in 1.

3. Action: Turn the needle around and insert it on the same side, but at a point approximately 4 mm from the incision edge (Fig. 10.6).

Rationale: This creates a stitch at right angles to the incision.

4. Action: Pass through the incision and bring the needle up at a point 4 mm from the incision.

Rationale: The path described by the suture material is a line at right angles to the incision.

5. Action: Tie a knot with the two ends after applying the appropriate tension.

Rationale: These sutures are stronger than horizontal mattress sutures in areas of tension. They are mainly used in the skin or fascia.

Halsted suture – the technique is essentially the same as for a vertical mattress suture except that two sutures are placed in a parallel fashion before they are tied (Fig. 10.7). This produces an interrupted pattern in which the edges of the wound are inverted.

Figure 10.7 Halsted suture pattern. (Reproduced with permission from Stephen Baines, Vicky Lipscomb and Tim Hutchinson: BSAVA Canine and Feline Surgical Principles, 2012, originally illustrated by Samantha J Elmhurst.)

Lembert suture – this is similar to the vertical mattress suture and is used to repair hollow organs. As the holding layer of an organ is the submucosa, the needle should penetrate only to this depth and never into the lumen. As the suture is tightened it inverts the tissues (Fig. 10.8).

Figure 10.8 (A) Lembert suture pattern. (B) Note how this inverts the tissues. (Reproduced with permission from Stephen Baines, Vicky Lipscomb and Tim Hutchinson: BSAVA Canine and Feline Surgical Principles, 2012, originally illustrated by Samantha J Elmhurst.)

Procedure: Gambee suture (Fig. 10.9)

This is a specialized suture used in the repair of the intestine.

Figure 10.9 Gambee suture. (Reproduced with permission from Stephen Baines, Vicky Lipscomb and Tim Hutchinson: BSAVA Canine and Feline Surgical Principles, 2012, originally illustrated by Samantha J Elmhurst.)

1. Action: Holding the needle in needle holders, insert the needle through the serosa of the intestine on one side of the incision.

Rationale: This is the outer layer of the area to be closed.

2. Action: Push the needle through the wall of the intestine right through to the mucosa and into the lumen and then return it through all the layers up to the serosal surface again (Fig. 10.9).

Rationale: When this is repeated on the other side, the suture will help to prevent excessive eversion of the mucosal surface.

3. Action: Now cross the incision and insert the needle down through the tissue layers on the other side; then bring the needle back up to the serosal surface again (Fig 10.9).

Rationale: This completes the suture.

4. Action: Tie a knot with the two ends of the suture material.

Rationale: The aim of the suture is to reduce eversion of the mucosa and reduce wicking of intestinal contents to the serosal surface.

A modified Gambee is placed in the same way, but does not penetrate the lumen of the intestine.

Continuous suture patterns

A line of continuous sutures starts and ends with a knot, which decreases the amount of foreign material in the wound. Continuous sutures are much quicker to do, but if one of the knots comes undone the entire line unravels. Tension forces are distributed more evenly and a continuous suture line has been shown to have no more leakage than a line of interrupted sutures.

Procedure: Simple continuous suture (Fig. 10.10)

Figure 10.10 (A) Standard simple continuous suture pattern. (B) Running simple continuous suture pattern. (Reproduced with permission from Stephen Baines, Vicky Lipscomb and Tim Hutchinson: BSAVA Canine and Feline Surgical Principles, 2012, originally illustrated by Samantha J Elmhurst.)

1. Action: Holding the needle with needle holders, place a simple interrupted suture and knot it, but only cut the end of the suture material that is not attached to the needle.

Rationale: The knot should be positioned away from the incision (see simple interrupted above). This suture will be the anchor for the rest of the suture line.

2. Action: Insert the needle into the skin perpendicular to the incision and at an appropriate distance from the first suture.

Rationale: Sutures are usually placed at about 5 mm apart.

3. Action: Take the needle across to the other side and bring it up through the tissue directly opposite the entry point (Fig. 10.10A).

Rationale: Do not knot the suture.

4. Action: Insert the needle on the opposite side perpendicular to and 5 mm along the incision. Continue until you reach the end of the incision.

Rationale: The resulting suture line has sutures that are perpendicular to the incision below the tissue and advances forward above it (Fig. 10.10A).

5. Action: To end the line of sutures, tie a knot using the suture material attached to the needle and the last loop of suture that is exterior to the tissue.

Rationale: The knot must be secure to ensure that the whole line does not come undone.

A simple continuous pattern provides maximum tissue apposition and is relatively leak proof compared with a line of simple interrupted sutures.

Running simple continuous sutures (Fig. 10.10B) – in this pattern both the sutures below and above the incision advance along the line.

Subcutaneous sutures – these are placed in a simple continuous pattern below the skin and the bites of the suture lie vertical to the incision (Fig. 10.11A). They are used to eliminate dead space and to relieve tension on the skin sutures. This pattern should be used in conjunction with a buried knot(s). (See later description.)

Figure 10.11 Suture patterns: (A) subcutaneous; (B) intradermal.

Intradermal sutures – these are often used to replace skin sutures and to reduce scarring. They are useful to reduce patient interference and to eliminate the need for suture removal in sensitive areas (e.g. post castration or in fractious patients). The suture is started by burying the knot in the dermis (see later description) and the suture line lies intradermally. The bites of the suture lie parallel to the line of the incision (Fig. 10.11B) and the suture line is completed with another buried knot. Absorbable suture material should be used.

Procedure: Ford interlocking suture (Fig. 10.12)

Figure 10.12 Ford interlocking sutures. (Reproduced with permission from Stephen Baines, Vicky Lipscomb and Tim Hutchinson: BSAVA Canine and Feline Surgical Principles, 2012, originally illustrated by Samantha J Elmhurst.)

1. Action: Holding the needle with needle holders, place a simple interrupted suture and knot it, but cut only the end of the suture material that is not attached to the needle.

Rationale: The knot should be positioned away from the incision (see simple interrupted above). This suture will be the anchor for the rest of the suture line.

2. Action: Bring the needle up through the loop of the suture and then cross the incision and insert it into the tissue on the opposite side as you would for a simple continuous pattern (Fig. 10.12).

Rationale: This action locks the simple suture in place.

3. Action: Take the needle across the incision and bring it up through the tissue on the opposite side. As the needle exits the tissue, bring it up through the loop of the previous suture.

Rationale: This locks the previous suture in place.

4. Action: Repeat as you go along the incision (Fig. 10.12).

Rationale: This interlocking suture is a form of ‘blanket stitch’ and can be placed quite quickly. It apposes the tissue more effectively than a simple interrupted pattern and distributes the tension better.

5. Action: To finish the line, insert the needle back down into the tissue on the same side as it has just been brought out from and pass it across the incision to exit on the other side. Retain the single end of the suture material on the first side. Tie the loop of material close to the needle to the single end. (Fig 10.12).

Rationale: The locking effect means that the line is less likely to unravel as a result of patient interference.

This pattern uses up more suture material than other patterns. It can be time consuming to remove as each loop must be cut individually to avoid pulling suture material that has been exposed to the external environment through the inner tissues of the wound.

Continuous Lembert sutures – these are interrupted sutures (Fig. 10.8) placed as a continuous line and are inverting sutures used to close hollow organs. The needle must not penetrate into the lumen and the suture bites are placed perpendicular to the incision as in the vertical mattress suture pattern.

Continuous horizontal mattress sutures – start with a simple interrupted suture and then continue with linked sutures as described above (Fig. 10.5). The suture bites are parallel to the line of the incision. More tension on the suture line will produce greater tissue eversion.

Specialized suture techniques

A. Purse ring suture (Fig. 10.13) – This technique may be used to close visceral stumps and to secure percutaneous tubes into a viscus such as may be seen in gastrostomy and cystostomy procedures.

Figure 10.13 Purse ring suture. (Reproduced with permission from Stephen Baines, Vicky Lipscomb and Tim Hutchinson: BSAVA Canine and Feline Surgical Principles, 2012, originally illustrated by Samantha J Elmhurst.)

Procedure: Purse ring suture

1. Action: This suture is placed before you insert an ‘ostomy’ tube, or may be used to reduce a rectal prolapse or to temporarily close the anal sphincter prior to surgery of the rectum. It may also be used to close a hole in the thoracic wall after penetration by a foreign body (e.g. a stick).

Rationale: If you place the suture after you insert the tube, you may compromise the tube lumen. Placing a purse ring suture around the anal sphincter prevents the passage of faeces, which may contaminate the surgical site – do not forget to remove it!

2. Action: Place a line of running sutures around the stump or – ‘ostomy’ tube so that the suture needle ends up at the same point as it started.

Rationale: When this is pulled tight it will gather up the tissue like the top of a cloth purse.

3. Action: Leave a length of suture material free from each end.

Rationale: This will allow you to pull the suture tight and will be used to tie the knot.

4. Action: Pull up the ends of the suture around the tube and tie the ends together (Fig. 10.13).

Rationale: This will create a seal around the tube.

5. Action: If the purse ring suture is around a penetrating foreign body, slowly withdraw the foreign body as you tighten the suture.

Rationale: This will create a seal as the hole is vacated. It may be necessary to roll the edges inwards with an instrument to achieve mucosal inversion and a tight seal.

B. Quilled suture (Fig. 10.14) – A quill is material such as a piece of rolled gauze or a piece of tubing from an old giving set that is used to distribute the tension of a suture over a greater surface area. You can use either vertical or horizontal mattress sutures.

Figure 10.14 Quilled vertical mattress suture. (Reproduced with permission from Stephen Baines, Vicky Lipscomb and Tim Hutchinson: BSAVA Canine and Feline Surgical Principles, 2012, originally illustrated by Samantha J Elmhurst.)

Procedure: Quilled sutures

This uses vertical mattress sutures and tubing from a giving set.

1. Action: Cut two pieces of intravenous drip tubing to the approximate length of the incision.

Rationale: You can use two pieces of rolled up gauze instead of tubing.

2. Action: Insert the needle approximately 8–10 mm away from the edge of the incision on the far side.

Rationale: This will allow sufficient space to place the mattress suture at right angles to the line of the incision (Fig. 10.6).

3. Action: Pass through the incision line and bring the needle up through the tissue at an equal distance from the edge on the near side of the incision.

Rationale: This is the same reason as no. 1.

4. Action: Turn the needle around and insert it on the same side, but at a point approximately 4 mm from the edge.

Rationale: This creates a stitch at right angles to the line of the incision.

5. Action: Pass back through the incision and bring the needle up at a point 4 mm from the far edge.

Rationale: This has now created a loop on the near side of the incision through which you place the piece of tubing.

6. Action: Before you pull the suture material completely through, place a short length of the tubing under the suture on the near side and then pull the suture tight (Fig. 10.14).

Rationale: The tubing should lie parallel to the line of the incision. Pulling the suture tight will hold the tubing in place.

7. Action: On the far side of the incision, place the other piece of tubing parallel to the incision and between the two entry points of the suture. Secure the suture with a knot, which should lie on top of the tubing.

Rationale: This will hold the tubing in place on the far side (Fig. 10.14).

8. Action: Continue to place a line of interrupted vertical mattress sutures along the incision line so that each one helps to hold the piece of tubing in place (Fig. 10.14).

Rationale: The two lines of tubing help to spread the tension from the suture over a greater surface area.

C. Chinese finger-trap suture (Fig. 10.15) – This is a technique consisting of a series of knots that is used to secure a tube such as a suction drain to the skin. Tension on the tube increases as the tube is pulled, thus preventing its removal.

Figure 10.15 A Chinese finger-trap suture used to secure an active suction drain. (With permission from Baines S, Lipscomb V and Hutchinson T (2012) Manual of Canine and Feline Surgical Principles. BSAVA Gloucester, p 289.)

Procedure: To tie a Chinese finger-trap suture

1. Action: Place a simple interrupted suture in the skin at a point close to the exit of the tube.

Rationale: This will form a firm attachment of the tube to the body.

2. Action: Leave both ends of the suture material long.

Rationale: These ends will allow you to wind them along the length of the tube.

3. Action: Take one end between the thumb and forefinger of your left hand and the other end in your right hand and pass them over each in the front of the tube and form the first throw of a simple knot.

Rationale: You can tie a full surgical knot if you want, but one throw is usually sufficient to anchor the tube. The tension on the throw should slightly indent the tube, but must not be so tight that it occludes the lumen of the tube.

4. Action: Cross them over each other behind the tube and perform a throw again.

Rationale: The suture will have moved along the tube.

5. Action: Cross them over each other in front of the tube and perform another throw.

Rationale: The gap between each knot should be about 0.5–1 cm.

6. Action: Repeat this at least 5–6 times and terminate with a secure knot consisting of several throws.

Rationale: The suture material will have entwined the tube in a net-like structure, which will hold it firmly in place (Fig. 10.15).

Suture removal – sutures should be removed once there is sufficient healing to prevent the wound reopening. This is usually at 10–14 days, but healing may take longer in debilitated patients or if there has been patient interference. If sutures are left in for too long then granulation tissue may cover the knots, making removal both difficult and painful.

Knots

A knot may be defined as two throws laid one on top of the other and tightened. It is the weakest point in a line of sutures and if it is incorrectly tied it will come undone and lead to reopening of the wound, which at the very least will delay healing but most severely could lead to evisceration and other complications.

Knot security depends on:

• The type of suture material – multifilament suture materials tend to have better knot-holding ability than monofilament suture materials (Table 10.1).

• The length of the cut ends – if they are too short the knot may unravel.

• The structure of the knot.

The tension applied to the knot is also important. The knot should not be too tight unless it is used as part of a ligature for haemostasis. Excessive tension may strangulate the tissue and will cause the patient some discomfort, which may lead to patient interference.

Knots may be tied:

• Using instruments – this is easier and more common than using hand tying and the advantage is that there is less wastage of suture material. There may be a loss of feeling when using instruments, but once you are proficient you will learn to gauge the tension of each throw.

• By hand – this technique is useful in confined or hard-to-reach spaces or when sutures have been preplaced (e.g. in closure of a thoracotomy). It is usually necessary to leave the ends of the suture material longer than when using instruments, which can lead to wastage. The technique may be one handed, which is useful in small spaces, or two handed, which allows better control.

Types of knot

The type of knot (Fig. 10.16) formed tends to depend on the surgeon’s technique.

Figure 10.16 Types of knot.

Procedure: Tying a square knot using instruments

1. Action: Place a simple interrupted suture and leave the two ends of suture material free.

Rationale: One end attached to the needle will be longer than the other end, which should be about 2–3 cm long.

2. Action: Holding the needle holders in your right hand, place the tips between the two strands of suture material and wrap the strand nearest to you (long end) around the needle holders to form a loop.

Rationale: The long end is attached to the needle.

3. Action: Open the tips of the needle holders a little and grasp the short end of the suture material.

Rationale: The short end is the end without the needle.

4. Action: Bring the short end through the loop towards you by reversing your hands and tighten the suture gently.

Rationale: You have now formed the first throw.

5. Action: Now wrap the strand furthest away from you (long end) over the needle holders to form a loop.

Rationale: This is the beginning of the second throw.

6. Action: Open the tips of the needle holder a little and grasp the short end of the suture material and pull it through the loop.

Rationale: Gently allow this throw to form the knot to prevent the suture tightening excessively.

7. Action: Keep your hands low and parallel to prevent the knot tumbling.

Rationale: Each throw should be directly on top of the other if it is not to become a half-hitch (Fig. 10.16).

NB Even pressure must be applied to each end; if one end is pulled with greater tension than the other a half-hitch will form. Hands should be on the same level – if one hand is lifted the suture will tumble and form a sliding two-half-hitch knot. If the ends are crossed incorrectly a granny knot will form (Fig. 10.16). Tumbled knots, half-hitches and granny knots are incorrect and may come undone.

Square knot – this is the most common type of knot and is used to anchor most suture patterns.

Slip knot – this is the same as a square knot except that the tension is uneven. One strand is held with more upwards pressure, resulting in a knot that can slide easily to tighten or to loosen.

Surgeon’s knot (Fig. 10.16) – this is similar to the square knot except that the first throw has the strand of suture material thrown over the needle holders twice before the short strand is pulled through. This has the advantage of creating more friction so that the first throw is kept snug while the second standard throw is placed on top. A surgeon’s knot is asymmetrical so must be followed by a square knot on top to ensure security.

Buried knots – this technique is used to start a line of subcutaneous or intradermal sutures to reduce the irritation that may be caused by the knots rubbing against superficial tissues. To bury the knot, introduce the needle deep in the far subcutaneous or intradermal tissue passing it up into the tissue, across the incision and then down into the tissue on the near side (Fig. 10.17), exiting deep in the incision line. Now form a knot, which will be buried within the incision line.