Intestinal surgery (part 2) (Proceedings)

Intestinal resection and anastomosis is a relatively commonly performed surgical procedure in small animals. Observing surgical principles and utilizing selected ancillary techniques help to reduce complications. Ancillary techniques that help reduce complications of intestinal resection and anastomosis include enteroplication and intra-operative peritoneal lavage. Potential indications for enteroplication will be reviewed, as its use is somewhat controversial in veterinary patients.

Intestinal resection and anastomosis

Indications for intestinal resection and anastomosis include intussusception, neoplasia, focal necrosis (e g, foreign body, volvulus, trauma), perforation(s) (e.g., linear foreign body, gunshot wound, penetrating abdominal injury), and focally infiltrative disease (e.g., pythiosis). Extent of the resection should be based on extent of the disease process and assessment of the viability of the affected intestine. Excision of the dilated portion of the intestine is not usually performed, because the dilatation usually results from partial or complete obstruction. Intestinal viability is assessed visually, and such assessment is used to determine extent of resection. Criteria for assessing intestinal viability include presence of arterial pulsations, tissue color, character of blood from a partial-thickness test incision, wall texture, and peristalsis. The single most reliable criterion for assessing intestinal viability is the presence of arterial pulsations. Neoplastic and focally infiltrative lesions should be excised with wide margins of normal tissue. Plan the resection to preserve as much intestine as possible but also to avoid multiple anastomotic sites. Evisceration with self-inflicted intestinal trauma or mesenteric volvulus may necessitate massive resection and anastomosis and potentially result in short bowel syndrome.

Exteriorize and isolate the affected segment of intestine, and pack it off with moistened laparotomy sponges. Resection and anastomosis of the caudal duodenal flexure (duodenojejunal junction) and the ileocolic junction present additional challenges, in part, because of the short mesentery at these locations that tends to limit exteriorization of these segments. Presence of a linear foreign body with plicated intestine also presents challenges regarding exteriorization of intestine. Removal of the linear foreign body is indicated prior to the performance of a resection and anastomosis. Ligate the mesenteric vessels to the affected area, and incise the mesentery so as to preserve as much mesentery to make closure of the mesenteric defect easier. Occlude the intestinal segments atraumatically near the point of resection (assistant's fingers are least traumatic; Doyen intestinal forceps are also acceptable). Excise the affected intestine using a scalpel blade. Orient incisions to leave the antimesenteric border shorter than the mesenteric border on the remaining intestine. Correct any luminal disparity by longitudinally incising the antimesenteric aspect of the smaller end. Use 3-0 or 4-0 synthetic absorbable suture (e.g., polydioxanone) with an appropriately-sized swaged-on taper needle (e.g., SH) to perform the anastomosis. Place the first suture at the mesenteric border and the second suture at the antimesenteric border. Leave these initial sutures long to act as stay sutures when manipulating the intestine. Place sutures 3 to 4 mm apart, 4 to 5 mm from the wound margin, and through the full thickness of the intestinal wall to complete the anastomosis. Check for integrity of the anastomotic line by injecting saline (8 to 10 ml in a 6 cm segment of intestine) into the lumen of the occluded segment and observing for leaks. Place additional sutures, if leaks are observed. Cover the anastomosis with omentum, and close the mesenteric defect with a continuous suture line, while carefully avoiding mesenteric vessels.

Enteroplication

Enteroplication is a technique that is designed to promote the formation of controlled adhesions between adjacent loops of small intestine. A report of complications associated with enteroplication in small animals has been published.

The primary indication for performing enteroplication is in concert with an intestinal resection and anastomosis, particularly when used to treat an intussusception. Other causes of intestinal obstruction that require intestinal resection and anastomosis also may be candidates for an enteroplication procedure. In short, any situation in which controlled adhesion formation between segments of small intestine is desired may be an indication for performing an enteroplication procedure.

The technique used for enteroplication involves the use of multiple intestinal wall sutures. Principles of performing an enteroplication include the need to free all adhesions prior to plication, to include essentially all of the small intestine in the plication, to position the small intestine in gentle long loops (approximately 12 to 16 cm long) to avoid severe angulation to the intestine and possible obstruction, and to position the anastomotic site in the middle of a loop. Strategically place simple interrupted sutures (e.g.., 3-0 polydioxanone) near the antimesenteric borders of adjacent loops of small intestine. Depth of suture penetration should be adequate to incorporate the submucosa of each intestinal loop. Two or three sutures are placed between adjacent loops of intestine. Potential problems with enteroplication are the potential for fistula and abscess formation at suture penetration sites between adjacent loops of intestine and the potential for intestinal obstruction.

In summary, a technique for the production of controlled adhesion formation between adjacent loops of intestine is indicated primarily following intestinal resection and anastomosis. When properly performed, this technique should reduce the occurrence of intussusception following intestinal surgery and hence the need to re-explore postoperative patients.

Intra-operative peritoneal lavage

Often after intestinal surgery, particularly intestinal resection and anastomosis, and prior to body wall closure, the abdomen should be lavaged. Peritoneal lavage using large volumes (1 to 3 L) of warm, isotonic solution is beneficial for several reasons. It facilitates aspiration of contaminants (e.g., tissue fragments, bacteria, blood clots, and fat), and helps to warm the patient (particularly smaller patients). Intra-operative peritoneal lavage is technically easy to perform, requiring only a fluid source, suction apparatus, tubing, and suction tip. Fill the abdomen with warm, isotonic solution, and gently manipulate the abdominal contents to facilitate retrieval of particulate material. Evacuate the fluid, and repeat this process until no appreciable particulate material remains. Completely evacuate the lavage fluid prior to closure, as residual saline solution will impair peritoneal cavity defense mechanisms. Heparin (100 IU/kg) may reduce the entrapment of bacteria by fibrin, with the net beneficial effect being an improved clearance of bacteria from the peritoneal cavity. For patients with gross intraperitoneal contamination, heparin can be added to the last container of isotonic solution prior to its placement in the peritoneal cavity.

References & suggested reading

Applewhite AA. Diagnosis and treatment of intussusceptions in dogs. Compend Contin Educ Pract Vet 2002;24: 110-127.

Applewhite AA, Hawthorne JC, Cornell KK. Complications of enteroplication for the prevention of intussusception recurrence in dogs: 35 cases (1989-1999). J Am Vet Med Assoc 2001;219: 1415-1418.

Nawrocki MA, McLaughlin R, Hendrix PK. The effect of heated and room- temperature abdominal lavage solutions on core body temperatures in dogs undergoing celiotomy. J Am Anim Hosp Assoc 2005, 41: 61-67.