Key gastrointestinal surgeries: Intestinal anastomosis

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

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

SURGICAL OPTIONS

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

Sutures

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

Staples

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

For general perioperative considerations when performing this procedure, including diagnostic testing, patient monitoring, and postoperative support, please see the symposium introduction.

Figures 1,2

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).

Place stay sutures at the mesenteric and antimesenteric borders (Figure 3) to ensure that the remaining sutures are properly spaced and to facilitate intestinal manipulation.5 Start a simple continuous suture pattern at the mesenteric border, leaving the suture end long. Take bites about 3 mm wide and 3 mm apart, depending on the size of the intestines.2 If mucosa begins to evert, use a modified Gambee suture pattern: Pass the needle full thickness through the intestinal wall and then back through the mucosa on the near side. Then insert the needle at the mucosa-submucosa border on the far side to push the mucosa into the lumen, and pass the needle full thickness back out that side. Continue the pattern to the antimesenteric surface, and tie it in a knot to prevent a purse-string effect (Figure 4). Flip over the intestines to expose the opposite surface, and continue suturing back to the initial mesenteric suture and tie (Figures 5 & 6). Then close the mesentery with a simple continuous pattern of 4-0 absorbable suture material (Figure 7); take suture bites at the edge of the mesentery to avoid damaging the intestinal blood vessels.

Figures 3,4,5,6,7

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.

COMPLICATIONS

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

REFERENCES

1. Fossum TW. Surgery of the digestive system. In: Small animal surgery. 2nd ed. St. Louis, Mo: Mosby, 2002;369-414.

2. Brown CD. Small intestines. In: Slatter D, ed. Textbook of small animal surgery. 3rd ed. Philadelphia, Pa: WB Saunders Co, 2003;644-664.

3. Holt DE, Brockman D. Large intestines. In: Slatter D, ed. Textbook of small animal surgery. 3rd ed. Philadelphia, Pa: WB Saunders Co, 2003;665-682.

4. Ralphs SC, Jessen CR, Lipowitz AJ. Risk factors for leakage following intestinal anastomosis in dogs and cats: 115 cases (1991-2000). J Am Vet Med Assoc 2003;223:73-77.

5. Weisman DL, Smeak DD, Birchard SJ, et al. Comparison of a continuous suture pattern with a simple interrupted pattern for enteric closure in dogs and cats: 83 cases (1991-1997). J Am Vet Med Assoc 1999;214:1507-1510.

6. Coolman BR, Ehrhart N, Pijanowski G, et al. Comparison of skin staples with sutures for anastomosis of the small intestine of dogs. Vet Surg 2000;29:293-302.

7. Huss BT, Payne JT, Johnson GC, et al. Comparison of a biofragmentable intestinal anastomosis ring with appositional suturing for subtotal colectomy in normal cats. Vet Surg 1994;23:466-474.

8. Bellenger CR. Comparison of inverting and appositional methods for anastomosis of the small intestine in cats. Vet Rec 1982;110:265-268.

9. Milovancev M, Weisman DL, Palmisano MP. Foreign body attachment to polypropylene suture material extruded into the small intestine lumen after enteric closure in three dogs. J Am Vet Med Assoc 2004;225:1713-1715.

10. Ellison GW, Jokinen MP, Park RD. End-to-end approximating intestinal anastomosis in the dog: a comparative fluorescein dye, angiographic, and histopathologic evaluation. J Am Anim Hosp Assoc 1982;18:729-736.

11. Kudisch M, Pavletic MM. Subtotal colectomy with surgical stapling instruments via a trans-cecal approach for treatment of acquired megacolon in cats. Vet Surg 1993;22:457-463.

12. Ullman SL, Pavletic MM, Clark GN. Open intestinal anastomosis with surgical stapling equipment in 24 dogs and cats. Vet Surg 1991;20:385-391.

13. Thompson SE, Trenka Benthin S, Freeman LJ, et al. Laparoscopic small intestinal anastomosis (abst). Vet Surg 1992;21:407.

14. Allen DA, Smeak DD, Schertel ER. Prevalence of small intestinal dehiscence and associated clinical factors: a retrospective study of 121 dogs. J Am Anim Hosp Assoc 1992;28:70-76.

15. Rasmusen L. Stomach. In: Slatter D, ed. Textbook of small animal surgery. 3rd ed. Philadelphia, Pa: WB Saunders Co, 2003;592-618.

16. Yanoff SR, Willard MD, Boothe HW, et al. Short-bowel syndrome in four dogs. Vet Surg 1992;21:217-222.