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INTUSSUSCEPTION
Overview
The term intussusception (pronounced in-tuh-sus-sep-shun) is used to describe a condition in which one segment of the intestine (the intussusceptum) telescopes or invaginates into the lumen of and adjacent segment of intestine (the intussuscipiens). Intussusceptions may occur at any location in the gastrointestinal tract from the stomach to the large intestine, however, most commonly the bowel segments involved are the jejunum (in the middle of the small intestine) or the ileocecocolic junction (where the small intestine joins the large intestine or colon. Generally the intussusceptum is a more proximal portion of bowel (i.e. closer to the mouth) which telescopes into a more distal (closer to the anus) segment. This pattern follows the normal direction of peristalsis. The reverse, however, is occasionally found.
Figure 1. Illustration of an intussusception showing the invaginated intussusceptum (blue) and the invaginating intussuscipiens (red) . (A) demonstrates a direct or normograde intussusception occurring in the direction of normal peristalsis. (B) demonstrates an indirect or retrograde intussusception occurring against the normal direction of peristalsis.
Figure 2: An intra-operative view of an intussusception Notice that one section of the small intestine has telescoped into the adjoining section.
Causes
Most commonly intussusceptions are associated with some problem that causes inflammation of the intestine (enteritis). Common causes of enteritis are intestinal parasites (hookworms, whipworms, and roundworms), protozoal, bacterial or viral infections (Giardia, Salmonella, canine distemper, and parvovirus), intestinal foreign bodies (bones, plastic toys, etc.), abrupt dietary changes, intestinal masses (tumors) and any surgical procedure performed on the intestine. Increased motility in a segment of intestine (hypermotility) which is adjacent to a segment that has lack of motility (ileus) can cause the hypermotile segment to telescope into the segment with ileus, resulting in an intussusception.
Incidence and Prevalence
Intussusceptions occur mostly in dogs and rarely in cats. The German shepherd dog may have a higher incidence of intussusception than other breeds. More commonly, intussusception occurs in young dogs, (less than a year of age) possibly because of the higher incidence of parasite problems and viral enteritis (distemper and parvovirus)
Signs and Symptoms.
Dogs that develop intussusceptions have generally been having episodes of diarrhea or vomiting before the intussusception occurs. Small volumes of bloody diarrhea, abdominal pain, or a palpable abdominal mass are suggestive of an intussusception. The severity of the clinical signs depends somewhat on the location of the intussusception, with problems lower in the intestinal tract causing less severe clinical signs. Intussusceptions can be chronic or intermittent, meaning that they will reduce themselves spontaneously and then reform.
When to seek Veterinary care
Dogs or cats with a history of vomiting or diarrhea for more than a day or two should be evaluated by a veterinarian, particularly if associated with depression, and loss of appetite.
Physical Exam, Testing, and Differential Diagnosis
Intussusception should be a consideration in a patient with a history of vomiting or diarrhea that has a palpable mass in the abdomen. The mass can be felt as a thickened sausage shaped intestinal loop. Occasionally the small bowel can be felt entering the mass. Radiographs will show a typical pattern of intestinal obstruction with gas and fluid filled dilated loops of bowel if the obstruction caused by the intussusception is complete. In cases of partial obstruction, there may not be significant signs on plain radiographs and a barium contrast study may be needed to identify the problem. If ultrasound examination of the abdomen s available, the intussusception area can often be identified, (Figures 3a and 3b) making this exam preferential to the barium series which requires multiple X-rays, more time, and creates a problem of liquid barium at the surgery site if a section of bowel has to be removed to repair the problem.
Figure 3a,b: Ultrasound views of an intussusception. Figure 3a shows a transverse view. Alternating hyperechoic and hypoechoic concentric rings are present within the lumen of a distended loop of bowel, giving the typical "target" sign.
Figure 3b shows a longitudinal view of the intussusception. Notice that multiple layers of bowel wall are within the lumen of the intussuscipiens.
Intussusception must be differentiated from all other causes of intestinal obstruction. These include:
- Intestinal foreign bodies
- Intestinal volvulus (a twisting of the intestine)
- Intestinal tumors
- Intestine trapped in a hernia
- Intestinal infections causing marked thickening or abscess formation
- Ileus (loss of motility from any cause-frequently seen with parvoviral enteritis
Treatment options
Occasionally intussusceptions can be manually reduced by manipulation of the affected bowel through the abdomen. They will also occasionally reduce themselves spontaneously. In most cases, however, surgery is required to treat this problem. Recurrence of intussusceptions is common, so even the intussusception can be manually reduced, surgery is often recommended to perform procedures designed to decrease the incidence of recurrence. During surgery the affected area bowel is easily identified (Figure ). It is occasionally possible for the surgeon to manually reduce the intussusception. Many times, however, either the intussusception cannot be reduced, or the bowel is so badly damaged that resection of the affected bowel is required. In this case, the area of damaged bowel is removed and the cut ends of the intestine are joined together with sutures or staples (a procedure called an intestinal anastomosis).
Because most patients that develop intussusceptions have had episodes of vomiting and diarrhea, the hydration and electrolyte status of the patients should be addressed prior to surgery if possible. This involves some blood chemistry analysis and treatment with an appropriate intravenous fluid. Treatment of animals with intussusception can be complicated and difficult. Many veterinarians prefer to send these patients to a surgical specialist for care. To find an ACVS Veterinary Surgeon in your area, click here.
Prognosis and Complications Following Treatment
The prognosis following surgical repair of an intussusception depends on several factors including the duration of the problem, the amount of intestine involved, the location of the problem and the extent of the blockage that has been caused. Intussusceptions that are chronic almost always require removal of a section of bowel and anastomosis of the ends to re-establish bowel integrity. Anytime bowel has to be removed there is a chance of leakage from the surgery site which can result if potentially fatal peritonitis. Patients that are in poor condition because of the intussusception may have a diminished ability to heal, making leakage more likely. If large amounts of bowel have to be removed, the patient may not do well because of the relatively short length of bowel left behind. Generally a high obstruction, (close to the stomach) will cause more severe vomiting and result in more serious dehydration and electrolyte disturbances, which may make anesthesia a more risky procedure. If an intussusception only causes a partial obstruction, the patient will not have nearly the extent of clinical signs that are present in those with a complete obstruction.
The prognosis for patients with an intussusception are good as long as recurrence of the problem can be prevented, and excessive amounts of bowel do not have to be removed. It has been reported that between 11% and 20% of dogs will have a recurrence of the problem following surgical correction. The incidence is higher (25%) if only manual reduction and no surgery is done. A procedure known as enteroplication can be performed to prevent recurrence of the intussusception, however, may make the patient more susceptible to other complications such as intestinal obstructions with foreign material that may have been able to pass without complication if the bowel had not been plicated.
Aftercare
Post-operative care following intussusception involves efforts to manage pain, generally with opioids, which help to slow bowel motility as well. Re-establishment of hydration and normal electrolyte values is essential and appropriate intravenous fluids are generally used until the patient is back eating normally. Antibiotics may be required depending on the amount of contamination from the surgery and the preference of the surgeon.
—Dr. Aric A. Applewhite, DVM
Diplomate ACVS
—Dr. William R. Daly, DVM
Diplomate ACVS
Posted 8/21/2006
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