Suture Material, Suturing Techniques, and Knot Tying

Suture Types

Sutures are used to close wounds, to secure bleeding vessels, and to seal off visceral structures. A wide variety of suture materials are available, which vary in terms of size, material, content, and consistency. For purposes of explanation, sundry sutures can be divided into absorbable and nonabsorbable. Absorbable materials are broken down by the body’s enzyme systems and virtually disintegrate ( Fig. 5.1 ). Nonabsorbable sutures resist enzymatic action and remain more or less permanently (with the exception of silk, which is gone within 2 years) in the body ( Tables 5.1 and 5.2 , Fig. 5.2 ). Tensile strength, particularly over time, is greater with nonabsorbable sutures. Sutures are sized on the basis of U.S. Pharmacopeia (USP)-equivalent diameters ( Table 5.3 ). In infected tissues and otherwise dirty areas, absorbable sutures have an advantage in that they provide short-term tensile strength and then disappear. They are less likely to provide a foreign body nidus for continuous inflammation and infection and for subsequent sinus formation. On the other hand, abdominal closure in the face of gross infection is an indication for the use of nonabsorbable suture material, to minimize the risk of dehiscence and/or evisceration. Almost all modern sutures are swaged onto a needle ( Fig. 5.3 ). Needles generally may be divided into two overall groups: cutting and tapered. Cutting needles are used to penetrate denser and firmer tissues (e.g., fibrous tissue, periosteum, ligament fascia). Cutting needles have a triangular point ( Fig. 5.4 ). If the additional cutting edge is on the inside curve of the needle, it is a standard cutting needle. If it is on the outside curvature of the needle, it is a reverse cutting needle. Tapered needles have a cone-shaped tip and are ideal for penetrating soft tissue and for producing the smallest hole ( Fig. 5.5 ).

A number of needle variations and configurations are available to the surgeon. Straight needles are very well suited for subcuticular closures. Circle pop-off needle and sutures allow the suture to disengage from the needle with a slight tug. The latter is ideal for rapid placement and tying of individual stitches. A circle non–pop-off suture/needle is significantly longer and permits placement of several stitches from the singular length of suture. Most needles used for gynecologic surgery will be ½c (one-half circle) or ⅝c; the ⅝c is obviously closer to completing the circle than is the ½c. The next needle designation relates to relative size and gauge. Zero Vicryl (0-vicryl) is typically fitted to A CT-1 or CT-2 needle, whereas a 1-Vicryl is coupled to the larger CT (CT-0) or CT-X needle. On the other hand, finer suture (e.g., 4-0 or 3-0 Vicryl) is attached to a thinner SH needle ( Fig. 5.6A ).

Suture Selection

Suture should be selected on the basis of several parameters: (1) the volume of tissue to be secured, (2) the tensile strength of the tissue to be sutured, and (3) the potential for bacterial contamination. A general guideline that can guide a gynecologic surgeon recommends that the smallest suture that can adequately accomplish the work at hand is the best suture for the job. For example, to select a 0 or 1 suture to secure a small bleeding arteriole deep in the pelvis makes no sense when a 3-0 or 4-0 stitch would suffice. On the other hand, attempting to secure a uterine vessel pedicle or infundibulopelvic ligament pedicle with a 3-0 suture rather than a 0 suture is equally foolhardy. Braided suture has a greater propensity to become contaminated with debris and bacteria within the interstices of the braid compared with monofilament suture. Silk suture is easy to handle and easy to tie down; hence, it forms a secure knot. It should never be used in the urinary bladder and, for that matter, neither should any nonabsorbable suture material. Nylon suture is very strong but requires many throws to avoid unraveling. Polyester suture material has all the advantages of silk and better strength and integrity. Polypropylene (Prolene) does not adhere to tissue and is less reactive than nylon. It is ideal for situations in which tissues are infected or contaminated. A relatively recent structure concept has been developed by Covidien (New Haven, Conn.). The unidirectional barbed technology does not slip and does not require knot tying ( Fig. 5.6B ).