INTESTINAL ANASTOMOSIS is an important surgical procedure that connects two sections of the intestines once a diseased portion has been removed. A key concern is to prevent leakage at the anastomosis site and subsequent peritonitis, but this complication can be avoided if the procedure is done correctly and preventive measures are taken.
Indications for intestinal resection and anastomosis include devitalization, irresolvable obstruction or segmental dysfunction, or irreparable perforation of the intestines.1-4 These conditions can result from a variety of causes, including foreign bodies, intussusception, neoplasia, abscess, trauma, volvulus or torsion, herniation, neurologic disorders, chronic constipation (e.g. feline idiopathic megacolon), or ulceration secondary to corticosteroid administration.4 Intestinal resection and anastomosis are most frequently performed in dogs and cats because of foreign bodies, neoplasia, and trauma.4,5
Intestinal anastomosis can be performed with sutures, staples, or anastomotic devices.1-3,6,7 Intestinal anastomoses can be strengthened by omentalization or serosal patch graft techniques, which reduce the risk of postoperative leakage and improve vascularity.1
A sutured anastomosis is the most common option because of the availability and cost of materials and familiarity with the procedure. Perform sutured anastomoses with appositional suture patterns since inversion reduces the lumen diameter and eversion can increase adhesion formation.2,3,8 Avoid double-layer closure because of luminal compromise, poor submucosal apposition, avascular necrosis, and prolonged healing time.2
Monofilament sutures are recommended for sutured anastomosis because multifilament material has more drag and is more likely to promote inflammation.2 Although nonabsorbable suture can be used for anastomosis, avoid it when using continuous suture patterns because of potential luminal extrusion and subsequent foreign body entrapment.2,9 Swaged, tapercut needles penetrate easily through the submucosa, which is the holding layer of the intestines, and limit tissue trauma.5 Tapercut needles have a round shaft and a cutting point that can penetrate both delicate and dense tissue. Taper needles, which are more commonly found in practice than tapercut needles, are also acceptable for intestinal surgery.2
Simple continuous suture patterns are quick to perform and provide better approximation than interrupted patterns.2,5,10 Histologically, mucosal eversion is reported in 66% of simple interrupted closures while inversion, eversion, or malalignment is seen in only 38% of simple continuous closures.2,6 With both techniques, mucosal eversion can be reduced by trimming excess mucosa or by using a modified Gambee suture pattern.5
Using surgical staplers to anastomose intestines reduces surgery time and provides bursting strength, lumen diameter, and healing similar to anastomosis with simple interrupted sutures.6 Complications are reported in 13% to 14% of animals undergoing stapled anastomoses and include severe hemorrhage (13%), postoperative leakage at the anastomosis site (8%), and localized abscess formation at the staple line (4%).11,12
Anastomosis ring and laparoscopy
Other options for anastomosis include biofragmentable intestinal anastomosis ring placement and laparoscopic-assisted anastomosis.7,13 Little information is available in the veterinary literature on the clinical use of these techniques.
TECHNIQUE FOR SINGLE-LAYER CONTINUOUS END-TO-END INTESTINAL ANASTOMOSIS
To begin the procedure, isolate the affected area of intestines with moistened laparotomy pads. Ligate the blood vessels to the transection sites with absorbable suture (Figure 1); ligate the arcuate branches along the mesenteric surface by taking suture bites around the vessels immediately adjacent to the proposed transection sites. Milk luminal contents away from the area, and clamp the diseased intestines, along with 2 or 3 cm of healthy tissue, with Kelly or Carmalt forceps. Confine the luminal contents within the retained healthy intestines by using noncrushing forceps (e.g. Doyen intestinal forceps), umbilical tape, or Penrose drain tourniquets that collapse the intestinal lumen but do not inhibit blood flow. Alternatively, an assistant can occlude the intestinal lumen near the proposed transection sites with index and middle fingers. Place the occluding devices at least 3 cm away from the anastomotic ends to prevent interference with suturing. Transect the intestines adjacent to the ligated arcuate vessels. Luminal disparity can be corrected at this time by increasing the angle of the cut on the narrower segment of intestines so that the antimesenteric border of the intestines is shorter than the mesenteric border (Figure 2).
Check the anastomotic site for leaks by distending the segment with sterile saline injected into the lumen while continuing to occlude the intestinal segments distal to the site. Seal any leaks with interrupted sutures; the omentum can be tacked over the anastomotic site by using a separate omental flap for each side.
Potential complications include dehiscence, peritonitis from leakage or necrosis, ileus, recurrence of clinical disease, or short-bowel syndrome. Anastomotic leakage is reported in 3% of animals undergoing continuous sutured anastomosis and up to 11% of animals undergoing interrupted sutured anastomosis; leakage is more likely to be associated with anastomoses performed for foreign body removal or resection of traumatized intestines.4,5,14 The risk for anastomotic leakage also increases in patients with preexisting peritonitis or hypoalbuminemia.4 Dehiscence and leakage can be reduced by ensuring adequate blood supply, reducing tension across the anastomotic site, and providing adequate apposition.5
Ileus may result from chronic intestinal distention, excessive tissue handling, pain, sepsis, opioid use, or electrolyte imbalances.2 Magnesium, potassium, calcium, and fluid imbalances should be corrected, and food should be offered as soon as possible. Prokinetics such as metoclopramide, erythromycin, and lidocaine may be useful for stimulating motility.5,15
Resecting more than 70% of the intestines may result in short-bowel syndrome, depending on the site of the resection and the health of the remaining intestines.2,16 Maldigestion and malabsorption from reduced surface area will result in persistent watery diarrhea and weight loss. Dietary modifications, including increasing soluble fiber content, may reduce clinical signs.2
Anastomosis of the ileum to the distal colon or rectum in cats with megacolon may result in the development of watery feces because of loss of the ileocolic valve, which reduces access of colonic bacteria into the small intestines.3 Additionally, loss of ileum may reduce water absorption capacity of the intestines. Colocolic anastomosis results in more tension across the anastomotic site because the vascular pedicle to the ascending colon is shorter than that to the ileum.3
Karen M. Tobias, DVM, MS, DACVS
Ryan Ayres, BS
Department of Small Animal Clinical Sciences
College of Veterinary Medicine
The University of Tennessee
Knoxville, TN 37996-4544
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