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Suturing, Stapling, and Tissue Adhesion
Surgical procedures typically involve excision, resection, or transection to address a pathologic situation. Subsequent reconstruction, which includes maneuvers to secure a restoration of function, often allows the choice of a variety of methods. Surgical and general medical principles, safeguards, and prophylactic measures require planning, vigilance, and support across the health care spectrum to facilitate a completely successful result. Preoperative planning should be anticipatory, perioperative monitoring appropriate, surgical technique thoughtful and carefully executed, and postoperative care robust. Frequently during the course of a gastrointestinal (GI) or abdominal operation, whether for benign or malignant disease, a resection of a hollow viscus with subsequent reconstruction is required. The anastomosis often anchors the procedure. Successful healing influences the outcome positively. Conversely, anastomotic failures not only increase morbidity and permanent stoma rates but delay adjunctive therapy, increase the intensity and duration of hospital care, and are associated with increased rates of distal recurrence (of malignancy) and mortality (short-term and long-term all cause). Because a majority of the factors influencing an anastomosis's subsequent behavior are determined by the time a patient leaves the operating room, attention must first include the timing and choice of procedure, as well as the technique itself.
Wound healing proceeds in a stepwise, time-dependent fashion. Healing a GI anastomosis has parallels but important differences. No chronic wound exists in a healing anastomosis, a situation in which repair must allow for rapid recovery of tensile strength and function. The goal of eliminating anastomotic leaks is challenged by our poor understanding of this pathophysiology. The multilayered architecture, the heavy colonization of the lumen, the influence of the different bowel layers, the vasoactive vascular supply, and variations in the rate and process of healing set the GI tract apart from subcutaneous tissues.
When the bowel is surgically transected, there is an immediate inflammatory response elicited by activation of the clotting cascade and by recruitment of platelets. The inflammatory cascade is propagated via the release of inflammatory mediators stored in platelet granules. Neutrophils are subsequently mobilized into the wound. At this time, the collagen matrix is degraded by collagenases and metalloproteinases. Collagenolysis is necessary to create a local pool of amino acids, especially those unique to collagen—proline and lysine. The newly formed collagen “recycles” these amino acids. The extent of collagenolysis varies among tissue, proceeding along the sides of the wound for variable distances. These tissues undergoing collagenolysis around the wound become weaker than normal tissue and are the site most susceptible to failure in the early phases of wound healing. It is during this initial phase that the integrity of the anastomosis depends almost entirely on the mechanical sealing of the lumen by sutures or staples.
Between the third and fifth postoperative day there is a transition from the inflammatory phase to the proliferative phase of wound healing. With the proliferation of fibroblasts and smooth muscle cells, there is a shift from collagen degradation to collagen deposition. Once collagen deposition predominates over collagenolysis, the approximation of the two ends of bowel is no longer dependent on sutures or staples but on the cellular matrix surrounding the collagen fibers. Although bursting strength is 50% of normal in small bowel anastomoses (35% to 75% of normal in large bowel anastomoses) at 2 to 3 days post procedure, it approaches 100% by 7 days.
It is important to recognize that the time frames of tissue healing stages are shifted by factors impairing wound healing, potentially with catastrophic consequences. Corticosteroids, chemotherapeutics, and antirejection medications attenuate and prolong the inflammatory phase. Antiangiogenic drugs and nutrient deficiencies extend collagenolysis and blunt collagen synthesis, as does hypoxia. Similarly, the presence of local infection intensifies collagenolysis. Consequently, the selection of materials, sutures, and/or staples should be made with consideration to these factors.
Successful gastrointestinal anastomosis (GIA) healing relies on a good blood supply to the bowel that is not under tension as it is accurately (“watertight”) anastomosed. Adequate vascular supply includes local anatomy as well as systemic perfusion. Ischemia inhibits collagen deposition and maturation in particular. Tension leads to ischemia in addition to loss of closure (of the defect), especially with stapled anastomoses. Although the submucosa is the strongest layer of the bowel wall and must be included in all anastomoses, all layers of the bowel wall contribute to wound healing. Closure in the process of creating anastomoses must be watertight/airtight, involving healthy and “clean” bowel edges. Distal obstruction, whether mechanical or not, leads to increasing bowel diameter, with increasing wall tension resulting in local ischemia. Hypoalbuminemia represents a marker of a much broader physiologic derangement than just malnutrition. Animal experiments have demonstrated that the body prioritizes visceral wound healing over most other sources of protein consumption, including parietal wound healing.
As a GIA is created, the tolerance for anastomotic leak is essentially zero. Multiple approaches have been shown to be effective, including surgical stapling as equally secure to suturing under many conditions. The indications to staple are generally the same as those to suture. Given that surgical stapling or suturing is not equally applicable in every situation, the surgeons' facility with both techniques may vastly improve the outcome of an operation requiring an intestinal anastomosis. A number of older studies looked at differences between handsewn and stapled bowel anastomoses. In general, no differences were noted in the leak rate, morbidity, mortality, and cancer recurrence. A meta-analysis of the emergency laparotomy setting suggested, in the context of sparse evidence and high bias, neither technique was favored. Preference for handsewn repair of small bowel injuries in trauma settings remains strong.
Surgical Suturing and Technique
As with any other skill, handsewing an intestinal anastomosis requires practice. Having observed or done a few handsewn intestinal anastomoses under direct supervision does not necessarily allow for the development of the skills necessary to perform an anastomosis, particularly in critical situations (i.e., any situation where a stapler cannot be used). Therefore it may be to everyone's benefit (patient, surgeon, and operating team) to perform handsewn anastomoses, particularly in straightforward cases.
The ideal suture material for intestinal anastomosis is one that produces the smallest amount of tissue reaction while providing maximal strength during the lag or inflammatory phase of wound healing. All sutures result in some degree of tissue inflammation because the act of pulling the suture thread through the bowel wall causes some tissue injury. This inflammatory reaction affects levels of activated collagenases and matrix metalloproteinases leading to decreased tensile strength of the healing wound. It is critical to avoid this strength imbalance during the critical lag period (days 1 to 5) as the wound transitions from the inflammatory phase to the proliferative phase. Similarly, other factors that foster inflammation (e.g., necrotic tissue, debris, and infection) will delay healing of the anastomosis, and should be minimized.
In current clinical practice, most handsewn colorectal anastomoses are constructed with polydioxanone sutures. These possess most of the qualities of the ideal suture for this purpose. As a monofilament suture, coupled with an appropriate needle, it allows for the least amount of tissue injury from the act of suturing. It is slowly absorbed with good retention of strength for up to 6 weeks, well past the critical lag period.
With the pathophysiology of wound healing in mind, other types of suture and coatings have been experimented with. Application of basic fibroblast growth factor (bFGF) on the rat anastomosis was shown to significantly increase neovascularization, fibroblast infiltration, and collagen production around the anastomotic site, along with significant increases in the bursting pressure. Coating suture with a matrix metalloproteinase inhibitor (in this case, doxycycline) resulted in higher breaking strength in rat intestinal anastomosis. Using a knotless barbed suture for intestinal anastomosis has also been shown to be safe and reproducible. These adjuncts have variably reached clinical use, but warrant further research.
The adherence of bacteria to the suture material has been postulated as a possible explanation for bacterial infection and weakening of the intestinal anastomosis. Polydioxanone has been shown to have the lowest affinity to adherence of bacteria among the absorbable sutures. This same group of researchers showed that bacterial adherence is 5 to 8 times higher for braided versus monofilament sutures. Others showed the degree of infection in mice in the presence of suture correlated with the adherence properties of that suture for bacteria. A different group of researchers showed that polyglycolic acid suture had the highest rate of bacterial adherence, concluding that absorbable braided suture should not be used in closure of contaminated wounds or wounds at risk for developing infection.
With this evidence of suture potentiating wound infection, it is not surprising that research has focused on the effects of coating suture with antibiotic. Coating suture with an antibacterial agent (triclosan) significantly reduces adherent bacteria to polyglactin, is associated with decreased microbial viability and significantly increased bursting pressure in colonic anastomoses. PVDF (polyvinylidene fluoride; a permanent suture) coated with gentamicin was shown to increase the stability and bursting strength of colonic anastomosis in the rat. In summary, polydioxanone suture has low affinity for bacterial adherence, furthering its position as the suture of choice for intestinal anastomosis. Although there are animal data supporting the use of antibacterial-coated suture for this purpose, it will require human study before this becomes routine clinical practice.
Suture Methods
Suture lines can be created either in an interrupted fashion or in a continuous, running manner. The continuous suture has the advantage of being more watertight with the disadvantage that the integrity of the entire suture line is based on one stitch. Although hemostasis is also improved with a continuous suture, the converse effect, that continuous suture may constrict anastomotic blood flow leading to ischemia and anastomotic dehiscence, is also true. Most human studies indicate that a continuous anastomosis can be performed safely and quickly, with no significant difference between continuous and interrupted suture pattern.
Intestinal anastomosis can be constructed in a single-layer or double-layer method. Single-layer anastomosis consists of one layer of interrupted or continuous absorbable sutures, whereas a double-layer typically consists of an inner full-thickness layer of absorbable suture and an outer layer of interrupted absorbable or nonabsorbable sutures. Single-layer does not differ from double-layer anastomosis in terms of rates of anastomotic leak, perioperative complications, length of hospital stay, and mortality, while also shortening operative time and total cost. These findings were confirmed in a Cochrane review encompassing seven randomized controlled trials and 842 patients. Anastomosis in the trauma setting gravitates toward the double-layer anastomosis.
Anastomoses with the inverted technique heal faster with superior bursting pressure and more prompt return to normal bowel architecture. The majority of both animal and human studies indicate the superiority of the inverting anastomotic technique. Everted anastomoses are associated with increased rates of adhesion formation, anastomotic leak, wound infection, peritonitis, and fecal fistulation. Regardless of the suture particulars, a bowel anastomosis must adhere to the following principles (in addition to those articulated earlier): the anastomosis must be watertight and have mucosal apposition; the submucosa, which supplies much of the strength to a bowel anastomosis, must be incorporated into the closure; and care must be taken not to strangulate or instrument the edges of the bowel during closure to avoid stricture or necrosis and subsequent anastomotic leakage.
The Lembert suture is the most commonly used suture in GI surgery ( Fig. 85.1 ). It is used as the outer layer of a two-layer bowel anastomosis and is also used to repair seromuscular tears in the bowel wall. The stitch is started approximately 3 to 4 mm lateral to the incision and placed at a right angle to the long axis of the incision (“follow the curve of the needle”). It incorporates only the seromuscular layer; care must be taken to not incorporate the full thickness of the bowel wall. The tip of the needle is brought out close to the edge of the incision and is then reinserted in the apposing wound edge and brought out 3 to 4 mm lateral to the wound edge. The suture is then tied down to a tension that approximates the tissue but not tight enough to tear the tissue. The most commonly used material for a Lembert suture is either (3-0) silk or PDS. This stitch can be performed in an interrupted or continuous manner.
A horizontal mattress suture, or Halsted suture, is predominantly used for seromuscular apposition in multilayer bowel anastomoses (see Fig. 85.1 ). The suture is passed through the seromuscular layer 2 to 3 mm lateral to the wound edge and brought out at the wound edge; the needle is then passed through the opposing edge of the wound and brought out 2 to 3 mm lateral. On that same side of the wound, approximately 2 mm distal, the suture is passed through both edges of the wound to create two free ends of the suture on one side of the wound edge with the loop of the suture on the other side. This stitch is particularly useful in damaged, inflamed, or abnormal tissue where a Lembert suture pulls through the tissue. Because the horizontal mattress stitch distributes tension in a plane perpendicular to that of a Lembert suture, it allows for apposition of tissues with less crushing effect.
A purse-string suture is used to invert appendiceal stumps or to secure feeding tubes or drainage tubes in place. It is basically a circular continuous Lembert suture about a fixed point or opening in the GI tract. It is most commonly performed with nonabsorbable suture (see Fig. 85.1 ).
The Connell suture is a full-thickness, usually continuous, suture that allows for the mucosa to be inverted into the lumen of a bowel anastomosis (see Fig. 85.1 ). The suture is started at the edge of the anastomosis and brought, full thickness, from inside to out on one side and then outside to in on the opposite side. The suture is tied so that the knot is inside the lumen. The suture is then passed through the tissues from inside to out on one side to begin the Connell stitch. On the other limb of the anastomosis the suture is driven through the tissues, full thickness, from outside to in. On the inside of the bowel lumen the stitch is advanced 2 to 3 mm along the wall and then driven through the (transmural) bowel wall from inside to out on the same side. With the suture now on the outside of the bowel, the next pass is performed on the opposite side in an identical manner. This creates a U -shaped, full-thickness, running inverted suture line. It usually serves as an inner layer of a two-layer anastomosis. Absorbable sutures are generally used for these applications. The Cushing suture is the same as the Connell, except the suture does not enter the lumen, rather it exits through the submucosa.
The Gambee suture is an interrupted single-layer suture that inverts the mucosa into the lumen ( Fig. 85.2 ). The suture is brought full thickness from outside to in and then passed back through the mucosa to exit through the submucosal layer on the same side. It is then passed from the submucosa through the mucosa on the opposite limb. The final pass is a full-thickness one from inside to out on this side. The suture is tied extraluminally. This creates a full-thickness, inverting suture line. Absorbable sutures are typically used for this type of anastomosis. Some surgeons prefer the Gambee stitch for closure of a pyloroplasty; it is rarely used elsewhere.
A double-layer closure, also known as the Czerny-Lembert suture, is still considered by some as the “gold standard” of bowel anastomoses. This technique features an inner, full-thickness, continuous, absorbable suture layer surrounded by an outer layer of interrupted, often permanent, seromuscular (Lembert) sutures. Typically the deep or posterior outer layer is placed first, after (seromuscular) stay sutures of the lateral aspects of this layer had been placed to allow the bowel to be aligned. With the deep, outer layer completed between the stay sutures, a simple running suture of all layers commences in both directions of the posterior wall, converting to running Connell, or Cushing, on the anterior surface to meet in closure on the antimesenteric aspect. The anterior aspect of the second layer is completed last. The outer layer might be constructed with 3-0 silk, the inner transmural layer with 3-0 polyglycolic acid, polyglactic acid, or chromic gut suture.
A single-layer anastomosis begins at the mesenteric border and sequentially moves in both directions to the antimesenteric aspect. This can be done as interrupted or continuous suture. The interrupted approach described by Gambee used permanent suture (cotton or silk originally). The continuous suture described by others starts on the outside of the lumen at the mesentery. Using a double-armed suture to sew in both directions, it includes all layers except mucosa and will end on the antimesenteric border. Being on the outside, the two ends are tied to produce watertight/airtight anastomosis without compromising the luminal diameter. Polypropylene or polydiaxonone (3-0) are typically used.
Staplers and Stapling Technique
Staplers permit or facilitate surgical techniques, specifically resection, transection, and/or anastomosis, in a rapid, accurate, and reproducible fashion. Part of the attraction (historically) was the need to generate high-quality surgical work by individuals who did not possess the skills (training and/or experience) to successfully complete surgical maneuvers. The continued refinement of the stapler has allowed their widespread deployment and adaptation (to open, laparoscopic, or robotic uses) by all members of the surgical community. Although not a replacement for sound surgical judgment or competence, staplers enlarge the spectrum of approaches available to address problems, situations, pathologies, and/or locations.
Almost 200 years ago the Belgian surgeon Dr. Henroz DeMarche devised a ring for small bowel anastomoses that he tested successfully in dogs. In 1892 John B. Murphy of Chicago developed a sutureless metallic compression device for GIA. Both inventions were in recognition of high anastomotic leak rates with handsewn anastomoses. The “Murphy button” enjoyed human use for several decades. Concerned with spillage at a time of frequent gastric surgeries (resections, partial or complete), Húmer Hültt, MD, of Budapest developed a bulky stapler and elaborated several fundamental stapling principles. After World War II, the USSR's Scientific Institute for Surgical Devices made a major step forward studying and developing a number of staplers, thereby promoting safe, standardized surgical treatment nationwide. A visiting American surgeon from Johns Hopkins, Mark Ravitch, MD, brought a stapler to the United States in 1958, eventually leading to the founding of the United States Surgical Corporation and much research into and development of surgical stapling.
The principles underlying surgical stapling began with Húmer Hültt. He stressed compression of the tissue, placing (metal) staples in a closed “ B ” shape, with two rows of staples in a staggered formation. Similar to a standard office stapler, a B -shaped staple is formed from the interaction with an anvil. This action allows maintenance of the compression, with its hemostasis and watertight/airtight sealing, while encouraging viability, minimizing tissue damage, and stabilizing the new configuration. Formed in the tissue at the time of deployment, each staple, individually and collectively, contributes to these goals. The promotion of compression, accurate staple formation, and desired tissue configuration must underlie the methods needed in deployment of the stapler.
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