Chapter 70 Surgery of the Intestines
Surgical therapy is indicated for structural disease of the bowel. Most animals that require surgery of the small bowel are physiologically compromised. When obstruction of the small bowel is proximal in location (high obstruction), serious electrolyte and water abnormalities can place these patients at high risk.
Prophylactic antibiotics administered perioperatively are indicated in small bowel surgery.
• Before surgery of the upper and middle small bowel, give a first-generation cephalosporin such as cefazolin (20 mg/kg) intravenously (IV) initially; repeat IV 3 hours later.
• Before surgery of the distal small bowel and large intestine, give a second-generation cephalosporin such as cefmetazole (15 mg/kg) IV or cefoxitin (30 mg/kg) IV; repeat IV 3 hours later.
ANATOMY
• A portion of the proximal duodenum is supplied by the celiac artery and shares a source of blood with the right lobe of the pancreas via the pancreaticoduodenal artery.
ENTEROTOMY
Surgical Procedure
Technique
3. Place a 3-0 stay suture at both ends of the proposed enterotomy incision (Babcock forceps may be substituted).
4. Milk bowel contents away from the proposed enterotomy site; place non-crushing intestinal forceps (or an assistant’s fingers) across the bowel to minimize spillage.
5. Make a full-thickness stab incision into the lumen, using a #11 Bard-Parker scalpel blade. Place a suction tip in the bowel lumen and remove its contents. Enlarge the incision as needed with Metzenbaum scissors.
6. If removing a foreign body, perform the enterotomy over healthy bowel distal to the foreign body.
9. Close the enterotomy incision with 3-0 or 4-0 synthetic absorbable or monofilament non-absorbable suture material on a swaged-on taper-point or taper-cut needle. A full-thickness, simple interrupted or continuous appositional suture pattern is preferred.
11. Use omentum or a jejunal onlay patch to reinforce the suture line. I prefer to use omentum, even in relatively healthy tissue.
12. Some severely debilitated animals may benefit from placement of a jejunostomy tube for postoperative enteral nutritional support. (See Chapter 3 for nutritional support of critical patients.)
Postoperative Care and Complications
Short Term
• Monitor for signs of leakage peritonitis by abdominal palpation, body temperature measurements, and a complete blood count (CBC).
INTESTINAL RESECTION AND ANASTOMOSIS
Indications for intestinal resection and anastomosis include the following:
Preoperative Considerations
• Administer perioperative antibiotics starting 20 to 40 minutes before surgery, as described previously.
• Although controversy surrounds the choice of suture pattern for intestinal anastomosis, any of several techniques probably is acceptable in the hands of a competent surgeon who follows sound intestinal surgery principles.
• It is probably best to use synthetic monofilament absorbable sutures. Polypropylene used in a continuous pattern has been associated with attaching to foreign bodies after being extruded into the lumen of the bowel and was the cause of pyloric outflow obstruction in a dog following the formation of a granuloma around the suture.
• I prefer the simple interrupted appositional (SIA) suture pattern for intestinal (large or small) anastomoses. This non-crushing technique causes little compromise of the blood supply of the intestinal segments. (Disruption of vascularity is the most common biologic cause of failure of an anastomosis.)
• Assess bowel viability before determining the amount of bowel to be resected. Standard clinical criteria include color, peristalsis, and arterial pulsations.
• In the rare case in which standard criteria are not adequate to determine bowel viability, an intravenous fluorescein dye technique can be used.
• Inject 2 ml of 5% fluorescein dye IV; in a darkened surgery room, evaluate the pattern of fluorescence using #3600 ultraviolet illumination (Wood’s lamp).
Surgical Procedure
Objectives
• Remove the diseased or non-viable segment of bowel and restore bowel continuity with an end-to-end anastomosis.
Technique
1. Make a midline abdominal incision long enough to accommodate a thorough abdominal exploratory procedure.
3. Isolate and ligate the mesenteric vessels to the affected area. Ligate the arcadial vessels within the mesenteric fat similarly.
4. Place crushing clamps across the bowel at a 60 degree angle to the long axis of the bowel and just inside the arcadial vessels.
5. Milk the ingesta away from the crushing clamps. Place a non-crushing clamp across the viable segments of bowel to be anastomosed, or have an assistant gently hold the bowel segments during the anastomosis.
6. Excise the diseased bowel by incising between the crushing clamp and the arcadial vessel ligation.
7. The mucosal collar may evert around the ends of the transected bowel. This can be trimmed with scissors.
8. Atropine given in a mesenteric vessel at a dose of 0.04 mg/kg has been shown to decrease the amount of mucosal eversion of jejunal segments.
9. Correct lumen disparity by cutting the small lumen at a more acute angle, longitudinally incising the antimesenteric edge of the small end, or oversewing the larger end.
10. Use a 3-0 or 4-0 suture on a small taper-point needle to place the sutures. All knots are extraluminal.
11. Carefully place the first suture at the mesenteric border. The second suture apposes the antimesenteric border. Place sutures approximately 2 to 3 mm apart along the “near” side of the anastomosis. Include the entire thickness of the bowel. Pull down the sutures slowly so as to gently appose the edges of the bowel (SIA pattern). Alternatively, close the bowel in a simple continuous suture pattern (see study by Weisman et al for details).
