Approach Considerations
Laboratory investigation is usually not helpful in the evaluation of patients with intussusception, although leukocytosis can be an indication of gangrene if the process is advanced. With persistent vomiting and sequestration of fluid in the obstructed bowel, dehydration and electrolyte imbalance occur.
Ultrasonographic imaging has been found to have a high sensitivity and specificity in the detection of ileocolic intussusception. Abdominal radiographs can also reveal diagnostic characteristics of intussusception, but their sensitivity and specificity has been called into question.
If a segment of intestine is resected at the time of operative reduction, intestinal obstruction with edema, congestion, lymphocytic infiltration, and transmural infarction are typical findings.
Radiographs
After obtaining a thorough history and performing a careful physical examination, obtain plain radiographs of the abdomen with the patient in the supine and upright positions.
Plain abdominal radiography reveals signs that suggest intussusception in only 60% of cases. (See the images below.) Plain radiograph findings may be normal early in the course of intussusception.[13] As the disease progresses, the earliest radiographic evidence includes an absence of air in the right lower and upper quadrants and a right upper quadrant soft tissue density present in 25-60% of patients.
Abdominal radiograph shows small bowel dilatation and paucity of gas in the right lower and upper quadrants. 
Note intussusception in the left upper quadrant on this plain film of an infant with pain vomiting. Courtesy of Dr. Kelly Marshall, Children's Healthcare of Atlanta at Scottish Rite. These findings are followed by an obvious pattern of small bowel obstruction, with dilatation and air-fluid levels in the small bowel only. If the distention is generalized and the air-fluid levels are also present in the colon, the findings more likely represent acute gastroenteritis than intussusception.
A left lateral decubitus view is also helpful.[14] If the view exhibits air in the cecum, the presence of ileocecal intussusception is highly unlikely.
Limitations of radiography
Morrison et al concluded that, when interpreted by pediatric emergency physicians, abdominal radiographs have a low sensitivity and specificity for diagnosing intussusception.[13] In a prospective experimental study, 14 pediatric emergency physicians interpreted radiographs of 50 cases of intussusception and 50 matched controls; these interpretations showed a sensitivity of 48% and a specificity of 21%. In 11% of cases, the abdominal radiographs were incorrectly interpreted as reassuring.
Ultrasonography and CT Scanning
Hallmarks of ultrasonography include the target and pseudokidney signs. (See the image below.)
Abdominal ultrasonography reveals the classic target sign of an intussusceptum inside an intussuscipiens. One study reported that the overall sensitivity and specificity of ultrasonography for detecting ileocolic intussusception was 97.9% and 97.8%, respectively. The authors concluded that ultrasonography should be used as a first-line examination for the assessment of possible pediatric intussusception.[15]
Ultrasonography eliminates the risk of exposure to ionizing radiation and can help to depict lead points and residual intussusceptions. It also helps to rule out other possible causes of abdominal pain. Even so, ultrasonography is highly operator dependent; therefore, interpret results with caution.
The presence of ascites and long segments of intussusception can be used as sonographic predictors of failure for nonoperative management.[16] Sonographic detection of ascites, air, and absence of blood flow in the intestinal wall strongly suggest bowel gangrene.
Computed tomography (CT) scanning has also been proposed as a useful tool to diagnose intussusception (see the image below); however, CT scan findings are unreliable, and CT scanning carries risks associated with intravenous contrast administration, radiation exposure, and sedation.
CT scan reveals the classic ying-yang sign of an intussusceptum inside an intussuscipiens. Contrast Enema
The traditional and most reliable way to make the diagnosis of intussusception in children is to obtain a contrast enema (either barium or air). Contrast enema is quick and reliable and has the potential to be therapeutic.[17] (See the images below.)
Barium enema shows intussusception in the descending colon. 
Intussusception evident during air contrast enema prior to reduction. Courtesy of Dr. Kelly Marshall, Children's Healthcare of Atlanta at Scottish Rite. Exercise caution when performing contrast enema in children older than 3 years, because most of these patients have a surgical lead point, usually in the small bowel. The diagnostic and therapeutic yield of the enema is lower in these patients. Enema is contraindicated in patients in whom bowel gangrene or perforation is suspected.
Milbrandt K, Sigalet D. Intussusception associated with a Meckel's diverticulum and a duplication cyst. J Pediatr Surg. Dec 2008;43(12):e21-3. [Medline].
Soccorso G, Puls F, Richards C, Pringle H, Nour S. A ganglioneuroma of the sigmoid colon presenting as leading point of intussusception in a child: a case report. J Pediatr Surg. Jan 2009;44(1):e17-20. [Medline].
Sanni RB, Nandiolo R, Coulibaly Diaoudia MT, Vodi L, Mobiot ML. Acute intussusception due to intestinal Kaposi's sarcoma in an infant. Afr J Paediatr Surg. Jul-Dec 2009;6(2):131. [Medline].
Earl TM, Wellen JR, Anderson CD, et al. Small bowel obstruction after pediatric liver transplantation: the unusual is the usual. J Am Coll Surg. Jan 2011;212(1):62-7. [Medline].
Bai YZ, Chen H, Wang WL. A special type of postoperative intussusception: ileoileal intussusception after surgical reduction of ileocolic intussusception in infants and children. J Pediatr Surg. Apr 2009;44(4):755-8. [Medline].
Turkyilmaz Z, Karabulut R, Gulen S, et al. Role of nitric oxide and cyclooxygenase pathway in lipopolysaccharide-induced intussusception. Pediatr Surg Int. Aug 2004;20(8):598-601. [Medline].
Zanardi LR, Haber P, Mootrey GT, et al. Intussusception among recipients of rotavirus vaccine: reports to the vaccine adverse event reporting system. Pediatrics. Jun 2001;107(6):E97. [Medline].
Christie CD, Duncan ND, Thame KA, et al. Pentavalent rotavirus vaccine in developing countries: safety and health care resource utilization. Pediatrics. Dec 2010;126(6):e1499-506. [Medline].
[Best Evidence] Ruiz-Palacios GM, Pérez-Schael I, Velázquez FR, et al. Safety and efficacy of an attenuated vaccine against severe rotavirus gastroenteritis. N Engl J Med. Jan 5 2006;354(1):11-22. [Medline].
Zickafoose JS, Benneyworth BD, Riebschleger MP, Espinosa CM, Davis MM. Hospitalizations for Intussusception Before and After the Reintroduction of Rotavirus Vaccine in the United States. Arch Pediatr Adolesc Med. Jan 2 2012;[Medline].
Niramis R, Watanatittan S, Kruatrachue A, et al. Management of recurrent intussusception: nonoperative or operative reduction?. J Pediatr Surg. Nov 2010;45(11):2175-80. [Medline].
Weihmiller SN, Buonomo C, Bachur R. Risk stratification of children being evaluated for intussusception. Pediatrics. Feb 2011;127(2):e296-303. [Medline].
[Best Evidence] Morrison J, Lucas N, Gravel J. The role of abdominal radiography in the diagnosis of intussusception when interpreted by pediatric emergency physicians. J Pediatr. Oct 2009;155(4):556-9. [Medline].
Hooker RL, Hernanz-Schulman M, Yu C, Kan JH. Radiographic evaluation of intussusception: utility of left-side-down decubitus view. Radiology. Sep 2008;248(3):987-94. [Medline]. [Full Text].
Hryhorczuk AL, Strouse PJ. Validation of US as a first-line diagnostic test for assessment of pediatric ileocolic intussusception. Pediatr Radiol. Oct 2009;39(10):1075-9. [Medline].
Munden MM, Bruzzi JF, Coley BD, Munden RF. Sonography of pediatric small-bowel intussusception: differentiating surgical from nonsurgical cases. AJR Am J Roentgenol. Jan 2007;188(1):275-9. [Medline].
Shekherdimian S, Lee SL, Sydorak RM, Applebaum H. Contrast enema for pediatric intussusception: is reflux into the terminal ileum necessary for complete reduction?. J Pediatr Surg. Jan 2009;44(1):247-9; discussion 249-50. [Medline].
Jen HC, Shew SB. The impact of hospital type and experience on the operative utilization in pediatric intussusception: a nationwide study. J Pediatr Surg. Jan 2009;44(1):241-6. [Medline].
Sandler AD, Ein SH, Connolly B, Daneman A, Filler RM. Unsuccessful air-enema reduction of intussusception: is a second attempt worthwhile?. Pediatr Surg Int. 1999;15(3-4):214-6. [Medline].
Bonnard A, Demarche M, Dimitriu C, et al. Indications for laparoscopy in the management of intussusception: A multicenter retrospective study conducted by the French Study Group for Pediatric Laparoscopy (GECI). J Pediatr Surg. Jul 2008;43(7):1249-53. [Medline].
Fraser JD, Aguayo P, Ho B, et al. Laparoscopic management of intussusception in pediatric patients. J Laparoendosc Adv Surg Tech A. Aug 2009;19(4):563-5. [Medline].
Herwig K, Brenkert T, Losek JD. Enema-reduced intussusception management: is hospitalization necessary?. Pediatr Emerg Care. Feb 2009;25(2):74-7. [Medline].
Gilmore AW, Reed M, Tenenbein M. Management of childhood intussusception after reduction by enema. Am J Emerg Med. Oct 25 2010;[Medline].
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