Gastrointestinal Surgical Techniques in Small Animals. Группа авторов

3 Suture Patterns for Gastrointestinal Surgery

       Daniel D. Smeak

       Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO, USA

3.1 One‐ or Two‐Layer Closure

      Although this is still a controversial topic, both techniques have potential downfalls that could endanger an anastomosis. One would think two‐layer closures are better than one‐layer since they might provide added strength initially. However, they increase the inflammatory response in the early stages of visceral healing owing to the extra tissue handling, suture material, and ischemia of the inverted tissue cuff (Orr 1969; McAdams et al. 1970; Goligher et al. 1977). Excess inflammation at the healing site results in a weaker anastomosis as more collagen is broken down during the inflammatory and debridement phases of healing. Advocates of single‐layer closures argue that this technique results in a larger lumen with less damage to the tissue edges (Thornton and Barbul 1997). Currently, in most conditions, a single‐layer closure for most gastrointestinal repairs is considered adequate (Sajid et al. 2012). Provided the lumen is not compromised, double‐layer repairs are sometimes elected when the surgeon expects higher intraluminal pressures, or when the tissue edge is considered extra friable or when sutures in the first layer tend to cut through the tissue.

3.2 Tissue Inversion, Eversion, or Apposition

      Inverting suture patterns cause greater initial narrowing of the intestinal lumen (Bellenger 1982) but their main advantage is that these patterns provide more consistent initial leak‐proof closures (higher leak pressures). Everting patterns elicit greater adhesion formation to exposed mucosal edges, and provide the least leak‐proof closures, and therefore they are not currently recommended for gastrointestinal closure (Hamilton 1967). In theory, approximating (appositional) patterns accurately align tissue layers compared to inverting and everting patterns, and therefore, these patterns are now preferred for gastrointestinal closures. However, in practice, consistent tissue apposition with approximating suture patterns infrequently occurs when anastomoses were evaluated histologically. Nevertheless, direct apposition of all intestinal layers, particularly the submucosal layer, has been found to result in the most rapid direct bridging of the repair (Jansen et al. 1981).

3.3 Stapled or Hand‐Sutured Anastomosis

Stapled anastomoses are technically easier and faster but they do not replace adherence to the principles of good surgical technique for successful intestinal healing (Chassin et al. 1984). Regardless of technique, an adequate blood supply and absence of contamination or tension is paramount to successful repair. Linear staples in thicker visceral tissue may not purchase the strength holding layer on both sides of the staple line leading to a weakened repair (Snowden et al. 2016). It is critical that the correct staple leg length is chosen when visceral edges are edematous or inflamed. In most situations, linear staple cartridges with 3.5 mm staples are acceptable for most intestinal repairs in dogs and cats. Linear staples with 4.8 mm staples are chosen for thicker intestinal edges and for stomach repairs. Stapled anastomoses were not at more risk for dehiscence when performed in the face of septic peritonitis, unlike what has been encountered in hand‐sewn repairs in multiple retrospective studies (Snowden et al., 2016; Davis et al. 2018).

3.4 Appositional Suture Patterns

      3.4.1 Simple Interrupted

      The major advantage of simple interrupted suture patterns is the ability to precisely control tension at each stitch along the wound with variable spreading forces along the margins (Moy et al. 1992). Another advantage is that each interrupted stitch is a separate entity, and failure of the single suture or knot may be inconsequential. Interrupted suture patterns take longer to place and knot, the individual knots increase the volume of foreign material in repairs, and suture economy suffers. A retrospective study comparing simple interrupted and continuous appositional patterns for enterotomy and anastomosis in dogs and cats found a low and comparable rate of enteric leakage with either pattern (Weisman et al. 1999).

      3.4.2 Simple Continuous

      The major advantage of simple continuous patterns is the speed of placement, and they generally create a more leak‐proof closure when compared to their interrupted counterparts. Continuous lines use less suture and minimize exposure of knots that can untie or cause tissue reaction. Surgeons have less precise control of suture tension and wound approximation throughout the repair. Insecure knots, lack of adequate needle purchase of the strength holding layer, or suture breakage can have disastrous effects on gastrointestinal repairs.

      3.4.3 Patterns to Reduce Excess Mucosal Eversion

      After gastric and intestinal incision, it is common that muscle fibers within the wall contract, causing retraction and spasm. The underlying loosely attached mucosa aggressively everts and rolls over the incised edge of intestine or stomach. When simple interrupted or simple continuous sutures are placed while the mucosa is remains everted, true apposition of intestinal layers cannot be attained. Everted mucosa is caught between the incised edges. Intestinal healing in this instance is slowed, when compared to accurately aligned intestinal layers. Excess mucosal eversion also lowers leak pressure of the repair and may increase the incidence of adhesion formation. The Gambee and modified Gambee patterns help reduce mucosal eversion.

      3.4.3.1 Gambee

In the Gambee pattern on the first side, the needle is inserted 3–4 mm away from the cut edge of serosa directly through the full‐thickness wall of the intestine into the lumen (Figure 3.1a). The needle is backed up just enough to advance and pierce the middle of the cut surface of the everted mucosal edge. The second purchase on the opposite side begins with the needle inserted in the cut edge of the everted mucosa down into the lumen of the bowel. The needle is then advanced and driven full thickness directly from the bowel lumen to the serosa, catching 3–4 mm of wall. The advantage of this suture over the modified Gambee stitch (below) is that since the needle pierces the bowel wall full thickness, a good purchase of submucosa is guaranteed to be included with each needle bite.

      3.4.3.2 Modified Gambee

      In this suture pattern, the needle penetrates the serosa, muscularis, and submucosa, but the everting mucosal layer is not incorporated (Figure 3.1b). On the opposite side a mirror image of the needle purchase is taken; the needle incorporates the submucosa, muscularis, and serosa only. When the suture is pulled snuggly, the mucosa is buried within the lumen. This pattern can be used as a simple interrupted pattern or in a continuous fashion. Caution should be taken when considering this pattern. The downside to this modification is that the serosa and muscularis layers may be included, but because mucosal eversion hides the incised bowel edge, either the submucosa may not be included or too small of purchase if this layer is included, rendering the suture line susceptible to premature dehiscence (Kieves et al. 2014).

      3.4.3.3 Luminal Interrupted Vertical Mattress Pattern

      During intestinal anastomosis and other tubular anastomoses, occasionally the deep side of the bowel edges are difficult to mobilize and expose. In this instance, surgeons may elect to use vertical mattress