Gastrointestinal surgery (Proceedings)

Gastrotomy is a common procedure most often performed for removal of gastric foreign bodies. The procedure is facilitated with the placement of stay sutures at each end of the proposed incision. The body of the stomach is opened with a stab incision into the lumen in a relatively avascular area between the greater and lesser curvatures. The incision is continued with Metzenbaum scissors to create an opening large enough to remove the foreign material. Synthetic absorbable monofilament suture with a swaged-on taper needle is the material of choice for most gastrointestinal surgery. There are numerous techniques to choose from when deciding how to close the stomach. Regardless of the suture pattern, the common theme for all gastrointestinal surgery is inclusion of the submucosal layer in the closure. Full-thickness purchase of the tissue ensures that this holding layer is incorporated in the suture line. Specific options for gastrotomy closure include:

• Two-layer continuous inverting pattern

o Full-thickness simple continuous pattern followed by,

o Partial-thickness (seromuscular) Lembert or Cushing pattern

• Two-layer continuous inverting pattern

o Simple continuous to close the mucosa and submucosa followed by,

o Partial-thickness (seromuscular) Lembert or Cushing pattern

• Single-layer full-thickness simple interrupted pattern

• Single-layer full-thickness simple continuous pattern

For simple gastrotomy, the author prefers a single-layer simple continuous pattern with 3-0 monofilament absorbable suture. A two-layer pattern may be more appropriate if performing a partial gastrectomy or if there was a concern about tissue viability.

Enterotomy/enterectomy

Although there are several significant differences in the healing properties of the small and large intestine, the same suturing principles apply regardless of the location of the foreign body within the gastrointestinal tract. Gentle tissue handling, adequate tissue purchase, use of appropriate suture material, and proper suture placement will ensure a secure closure. Luminal compromise is not usually an issue with simple enterotomies, however some surgeons prefer to routinely close longitudinal incisions transversely to avoid this problem altogether. Inverting patterns have been proposed to minimize mucosal eversion and the formation of adhesions. However, since adhesions are an infrequent problem in small animals and since luminal diameter would be decreased by inverting the tissue, this technique is not recommended. Options for simple enterotomy closure include:

• Single-layer simple interrupted approximating pattern

• Single-layer simple continuous approximating pattern

End-to-end intestinal anastomosis is most commonly performed following removal of nonviable tissue due to foreign body obstruction or intussusception. As with enterotomy closure, single-layer approximating patterns are preferred. Simple continuous patterns are faster and use less suture material, which is not only economical, but also decreases the amount of foreign material in the abdominal cavity. Tissue apposition is also thought to be better. The concern about creating a purse-string effect with a continuous pattern can be avoided if a modified simple continuous pattern is performed. In this technique, two suture lines are used, one originating at the mesenteric border and the other originating at the antimesenteric border. Good visualization of the mesenteric knot is imperative as this is the most common site for leakage. A single-layer full thickness continuous suture line is placed from the mesenteric knot to the stay suture at the antimesenteric knot with tissue purchases 2mm from the wound edge and 2 to 3mm apart. This is repeated on the other side from the antimesenteric knot to the mesenteric knot. There is no difference in reported rates of dehiscence between animals with simple continuous anastomotic closures and animals with simple interrupted closures.

Clinical examples in GI surgery

Linear foreign body

Gastrointestinal obstruction with linear material is a unique situation most commonly associated with cats. Foreign bodies such as string, thread, or cloth are ingested and become anchored typically at the base of the tongue or at the pylorus. Peristalsis advances the foreign body into the intestine. However, as a result of the anchor, the intestine will gather around the foreign body. This plication of the intestines may cause a complete or, more often, partial obstruction. Intestinal peristalsis continues against the fixed material and may lacerate the mucosa and cause perforations along the mesenteric border.

Diagnosis of this condition can be challenging. A thorough physical examination may provide the most information. Abdominal palpation is frequently painful and may reveal a large mass of bundled intestines. Occasionally, careful oral examination may reveal the foreign material anchored around the base of the tongue. On abdominal radiographs, the appearance of 3 or more small, eccentrically located, luminal gas bubbles tapered at one or both ends was diagnostic for linear foreign body in one study. If the diagnosis is still uncertain, other imaging techniques such as upper gastrointestinal contrast studies or abdominal ultrasonography may be required. Ultrasonographic appearance of a linear foreign body is described as a central hyperechoic line with intestine plicated on either side. Contrast agents should be administered with caution as it has been reported that 16% of cats had intestinal perforation found at surgery.

Linear foreign bodies are considered surgical emergencies. Conservative management of linear foreign bodies has been reported. However, in that study 42% of cats that were initially managed medically ultimately went to surgery. Given that perforated intestine from the linear foreign body carries a 50% mortality rate, early surgical intervention is the treatment of choice. Multiple enterotomies are typically required for removal for linear foreign bodies. This allows for segmental removal of the material and minimizes the risk of iatrogenic perforation from too much traction. Simple enterotomies are closed with an appositional simple interrupted or simple continuous pattern using monofilament absorbable suture material. Sutures are placed 2mm from the incised edge and 2 to 3mm apart.

Depending on the extent of damage, intestinal resection and anastomosis may be indicated. Intestinal viability is based on assessment of subjective parameters such as color, thickness, arterial pulsation, capillary bleeding, and peristalsis. Due to the mesenteric fat, perforations along the mesenteric border can be difficult to identify and to suture appropriately. This is the most common site for dehiscence following intestinal resection and anastomosis. In this scenario, resection and anastomosis may be preferable to primary closure of the site in the mesenteric border of the intestine. Intestinal anastomosis is most commonly performed using a simple interrupted or a modified simple continuous pattern. If peritonitis is present or if the sutured intestine is of questionable viability, omentalization or serosal patching can be used to reinforce the site.

Intussusception

Gastrointestinal obstruction due to intussusception is an uncommon, but notable condition in the dog and cat. Intussusception occurs when a segment of intestine (intussusceptum) moves into the lumen of an adjoining segment (intussuscipiens). Intussusception has been reported at all levels of the gastrointestinal tract with ileocolic intussusceptions being most common. Causes have been attributed to intestinal parasitism, linear foreign bodies, previous abdominal surgery, and gastroenteritis, although often the cause is unknown. Diagnostic imaging is mostly used to confirm what is already suspected from abdominal palpation. The characteristic ultrasonographic appearance of an intussusception is a multilayered target-like image in the transverse plane and alternating hyperechoic and hypoechoic parallel lines in the longitudinal plane.

Surgical intervention is the treatment of choice for intussusception. At surgery, manual reduction of the intussusception should be gently attempted, but it is often not successful. If reduced, the involved intestine (or intussusceptum) is evaluated for perforations and viability. Intestinal resection and anastomosis is indicated when manual reduction fails or if the reduced tissue is devitalized. The resected segment should be submitted for histopathological evaluation to potentially identify the cause of the intussusception. Enteroplication (or enteroenteropexy) is recommended to prevent recurrence; however, complications may result from this procedure as well. Both intussusception recurrence and severe postoperative complications associated with enteroplication have been reported in the dog and cat.

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