Surgery - Will's Medic Portal

Suturing is the process of stitching tissues of the body together to maintain position and promote unionised healing. This usually requires a needle (typically curved) and thread. Although commonly used to repair wounds, they can be used to alter tissues in the body even when no wound was initially present such as to repair a congenital abnormality or create an anastomosis of the intestine, or to secure new material such as heart valves or mesh implants.

Part of a surgeon's job is to choose appropriate suturing materials and techniques depending on the specific task and patient they are presented with. A 'bite' refers to tissue being tissue being penetrated and therefore encompassed by a single pass of the suture needle during the stitch. Each bite must be controlled, as adequate thickness and depth is required to achieve proper wound closure.

Suturing - Common Patterns

Interrupted Sutures

In interrupted sutures, each stitch is individually tied. This creates a series of separate knots along the wound. This allows for precision in wound edge approximation, and allows for customization of tension per stitch. However, it can be more time-consuming to a continuous technique, and may also result in greater use of suture materials.

Continuous Sutures

Continuous sutures use a single strand of suture material to create a line of stitches along a wound. They are generally faster to place than interrupted sutures and ensure a roughly even distribution of tension along the wound. However, if one part of the suture fails, the entire line could be compromised.

Mattress Sutures

Mattress sutures take bites of tisssue both deep and superficial to the wound. They can be stitched horizontally or vertically relative to the wound. These provide better tissue eversion (turning the edges outward) than simple interrupted sutures, and offer increased strength/support. However, the increased compression may reduce the blood supply causing tissue ischaemia.

Subcuticular Sutures

For subcuticular sutures, they are placed underneath the surface of the skin, reducing visibility. This enhances their cosmetic outcome, as it also does not leave suture marks on skin, and reduces the risk of wound infection. However, subcuticular sutures don't provide the same strength as some other suture patterns, and are limited to use on superficial wounds.

Suturing - Common Materials

Needles

Needles are defined by their size, shape and tip. Most needles are curved, as these are easy to use in small spaces and can penetrate tissues with convenience via rotating the tip into the tissue. Straight needles can be used for shallow wounds to achieve precision and good cosmetic outcomes, but they require more space to manouevre so can't be used in deep tissues, such as inside the body in a surgery.

Not all needles need to be equally sharp. Blunt ends are less likely to injure the user or the patient, although they require more force per bite. The abdominal wall is usually sutured with a blunt needle, as there is a risk of serious consequences if there is an accidental perforation of the bowel.

Threads

Sutures can be made with absorbable or non-absorbable materials. Absorbable materials will break down within a couple of months of application, once initial healing is complete. 'Non-absorbable' in the context of sutures generally refers to those that won't break down within the several weeks since application. Not all will remain in the body permanently, but some can if they aren't removed. Long-term sutures can be helpful for tissues that will not heal to take the tensile strength on their own, or to hold synthetic materials in place. Non-absorbable materials can also be preferred for application and removal for wounds on skin as absorbable materials, often made with organic proteins, can react with local tissues.

Suture threads can be made up of one or more strands/filaments. Monofilament strands are low friction, and are waterproof. They result in minimal tissue trauma, reactivity and infection, and offer some more elasticity compared with multifilamnet sutures. They can, however, cause pain and damage weaker tissues, due to their relatively firm and sharp edges. Multifilament sutures can increase the risk of infection and reactivity, but they are more pliable, stronger, and more secure.