Definition

• Invagination of one intestinal segment into the lumen of the adjacent segment.
• Intussusceptions are classified according to their localization within the gastrointestinal tract.
• Ileocolic and jejunojejunal intussusceptions are the types most commonly encountered in small animals. Others that have been described include gastroesophageal, duodenojejunal, and cecocolic.
• The segment entrapped within the lumen of the intussusception is called the intussusceptum. The engulfing segment is called the intussuscipiens.
• Most commonly, the orad segment is found to be engulfed within the aborad segment.

Pathophysiology

• The exact mechanism of intussusception generation is not known.
• Many affected animals are young (<1 year of age), and have a history of recent enteritis.
• Gastrointestinal irritation may cause the orad segment to undergo a hyperperistaltic state, and invaginate into the more flaccid aborad segment.
• The occurrence of an intussusception leads to a mechanical obstruction of the gastrointestinal tract. This obstruction can be either partial or complete.
• Vascular compromise commonly occurs in the intussusceptum and can occasionally occur in the intussuscipiens. Compromise of venous drainage in the face of an intact arterial blood supply leads to marked edema and intramural hemorrhage that may eventually progress to extravasation of blood into the intestinal lumen.
• Persistence of the intussusception can lead to eventual decreased oxygen delivery to the mucosal layer. This can lead to the eventual failure of the mucosal barrier and loss of an effective barrier to bacteria and endotoxin entering the bloodstream from the bowel lumen.
• With time, vascular compromise can lead to intestinal necrosis and eventual leakage of contents into the peritoneal cavity. This leads to the development of septic peritonitis.

Systems Affected

• Gastrointestinal-mechanical obstruction, ileus.
• Cardiovascular-fluid loss (vomiting and diarrhea) can lead to hypovolemia.

Signalment

Signs

Causes

• Any disease that alters gastrointestinal motility may lead to an intussusception. Known causes include: enteritis, recent abdominal surgery, intestinal mural disease, and intestinal parasitism.
• Intussusceptions occur in 8–33% of dogs that undergo renal allograft transplantation and 5% of dogs that undergo hematopoietic cell grafts. The reason for this is unclear, but may be related to immunosuppressive drugs.

Differential Diagnosis

• Any disease that can cause vomiting and diarrhea.
• Some intussusceptions can be chronic in nature; therefore, a chronic history of vomiting and/or diarrhea does not rule out an intussusception. This list includes but is not limited to intestinal parasites, viral enteritis (e.g., parvoviral infections), bacterial enteritis, foreign bodies, inflammatory bowel disease, mesenteric volvulus, and intestinal neoplasia.

CBC/Biochemistry/Urinalysis

• Leukogram-can range from normal to leukopenia (especially with sepsis or parvoviral infection) to leukocytosis (either stress response or in some septic patients).
• Hematocrit can be elevated (dehydration or underlying hemorrhagic gastroenteritis) or decreased (cases of intraluminal hemorrhage).
• Biochemical analysis-can show derangements of electrolytes due to loss through vomiting or diarrhea. These can include hyponatremia, hypochloridemia, hypokalemia. May be azotemic (prerenal) if significantly dehydrated. May also be hypoalbuminemic due to effusive loss into intestinal lumen. This can occur in the event of intestinal permeation changes subsequent to eventual intestinal mucosal necrosis.
• Urinalysis-may reveal elevated specific gravity in response to dehydration.

Other Laboratory Tests

• May see elevated lactate levels due to vascular compromise to intestinal segment.
• Blood gas evaluation may reveal a metabolic acidosis secondary to dehydration and hypoperfusion. Alternately, if the obstruction results in primarily gastric vomiting (pyloric obstruction), a hypochloremic, hypokalemic, metabolic alkalosis may be present.

Imaging

• Plain radiographs may reveal an obstructive intestinal pattern. The degree of intestinal distention may be related to the degree of obstruction.
• Plain radiographs may or may not reveal evidence of a soft tissue mass consistent with the intussusception.
• With gastroesophageal intussusception, a soft tissue mass may be seen within the lumen of the esophagus near the esophageal hiatus of the diaphragm. These findings can be confused with a hiatal hernia, but the severity of the clinical signs typically associated with a hiatal hernia are much more mild compared to a gastroesophageal intussusception.
• Abdominal ultrasound is very helpful in the diagnosis of abdominal intussusceptions. The intussusception appears as a target patterned mass on transverse sections, and as a multitude of parallel lines on longitudinal sections.
• Upper GI contrast studies or barium enemas can be helpful in supporting the diagnosis of an intussusception.

Pathologic Findings

• Examination of the intussusception reveals a telescoping of a segment of bowel into the adjacent segment.
• Histopathologic examination reveals variable degrees of venous congestion, vascular compromise, bowel wall necrosis, and peritonitis.

Appropriate Health Care

Initial efforts should be focused on patient stabilization as well as correction of dehydration and existing electrolyte abnormalities.

Nursing Care

• Intravenous fluid administration to correct dehydration as well as replace anticipated ongoing losses through vomiting and diarrhea.
• Typically, isotonic crystalloids are used. Specific choice of fluid type is dictated by electrolyte derangements.

Activity

Recommend controlled activity for 10–14 days postoperatively.

Diet

• If patient is vomiting intractably-NPO. If this occurs postoperatively, ileus may be an underlying cause.
• Most patients can readily be fed within 24 hours of surgical correction.

Client Education

• Immediate surgical intervention is the recommended treatment for intussusceptions.
• Stress the importance of the identification and treatment of an underlying cause.
• Complications may include: perioperative mortality, septic peritonitis, protracted hospital stay to stabilize, and recurrence. Recurrence rates have been reported to be 6–27%.

Surgical Considerations

• Surgical correction should be performed as soon as the patient is stable enough to withstand anesthesia and surgery. This is a surgical emergency.
• A full abdominal exploratory should be performed to assist in the identification of any potential underlying causes. Also, multiple intussusceptions may be present in one patient.
• Some intussusceptions can be manually reduced by gently milking the intussusceptum from within the intussuscipiens. Upon reduction, the bowel may or may not be viable.
• In the event that manual reduction is not possible, or the bowel has questionable viability, an intestinal resection and anastomosis is necessary.
• Enteroplication has been proposed as a procedure for preventing recurrence. A recent article identified some dogs that necessitated a second surgical procedure to correct problems sustained from the enteroplication procedure. It is important to exercise care when performing this procedure. Briefly, the loops created in the bowel should be gentle, and sharp turns in the bowel loops are to be avoided. The submucosal layer of the adjacent loops of bowel should be included in the sutures, but the lumen should not be entered.

Drug(s) Of Choice

• The prophylactic use of antibiotics is recommended. The choice of antibiotics should be dictated by the bacteria that are encountered.
• Manual reduction of an intussusception is considered a clean surgical procedure, while an intestinal resection and anastomosis is considered a clean-contaminated procedure.
• Long-term antibiotic administration is not recommended except in cases in which septic peritonitis is present either preoperatively or postoperatively.

Contraindications

Some surgeons feel that medications that stimulate peristalsis (e.g., metoclopramide) are contraindicated due to the potential for facilitating an environment for the recurrence of an intussusception.

Patient Monitoring

• Postoperatively, patients should be maintained on intravenous fluids and pain medications.
• Most recurrences occur within the first few days of surgery, but recurrences have been reported up to 3 weeks after surgery.
• Intestinal dehiscence typically occurs 3–5 days postoperatively. The signs, diagnosis, and treatment of septic peritonitis are covered elsewhere in this book.

Prevention/Avoidance

Prevention of many of the underlying causes can be achieved through such actions as vaccination against parvovirus, intestinal parasite control, limiting situations in which patients can be exposed to dietary indiscretion or foreign body ingestion.

Possible Complications

• Recurrence-6–27% of patients.
• Septic peritonitis-may result from postoperative intestinal dehiscence or intraoperative contamination.
• Short bowel syndrome is a rare complication that can occur with massive resections (generally >70% in dogs) of the small intestine.

Expected Course and Prognosis

• Highly dependent upon underlying cause, location of intussusception, and condition at presentation.
• Generally, as the intussusception moves more aborad, the prognosis improves as these patients are less severely affected. Gastroesophageal intussusceptions have a grave prognosis with mortality rates approaching 95%, while intestinal intussusceptions hold a good prognosis.

Associated Conditions

• Can be associated with intestinal parasites, viral enteritis, intestinal mural diseases.
• Gastroesophageal intussusceptions are typically associated with an underlying esophageal disorder.

Age-Related Factors

Younger patients are typically affected with underlying enteritis (viral or bacterial) or intestinal parasitism. Older patients are more commonly affected with intestinal neoplasia.

See Also

• Gastrointestinal Obstruction
• Peritonitis

Abbreviations

• GI = gastrointestinal

Author S. Brent Reimer

Consulting Editor Stanley L. Marks

Client Education Handout Available Online