Vanessa Tamas and Paul Ishimine
Intussusception is an invagination of any segment of the intestine. This occurs when the proximal portion of the intestine invaginates into the distal, adjacent part. The majority of pediatric intussusceptions are ileocolic in origin (1).
Intussusception is the most common cause of intestinal obstruction in children, occurring with a frequency of 56 per 100,000 children per year (2) Typically, intussusception occurs in children less than 2 years of age, with most episodes occurring between the fifth and the ninth month. However, intussusceptions have been reported throughout the age spectrum, from the neonatal period through adulthood (3).
Idiopathic intussusceptions account for more than 90% of cases (4). Viral illness, immunization against rotavirus, and pharmaceuticals that include promotility medications and oral antibiotic agents have been implicated in these patients (5). In up to 10% of cases, a cause for intussusception is found, usually a well-defined pathologic lead point. A lead point is found with some frequency after 4 years of age, and is found consistently after 14 years of age (6). Conditions associated with intussusception include lymphoma, Henoch–Schonlein purpura, hemolytic-uremic syndrome, Meckel diverticulum, familial polyposis, Peutz–Jeghers syndrome, mesenteric adenopathy, and inverted appendiceal stumps. The possibility of an underlying lead point should be considered in patients who present with recurrent episodes, those out of the typical age range, and those with small bowel–small bowel intussusception. Irrespective of cause, early diagnosis is essential; the duration of intussusception before treatment bears a close relationship to its morbidity and mortality.
CLINICAL PRESENTATION
The cardinal symptoms of intussusception are abdominal pain, vomiting, and rectal bleeding (1). In a typical case, there is a sudden onset of severe abdominal pain that may last several minutes. After an asymptomatic interval, repeated paroxysms will cause the child to cry out again. The child may be impossible to console or may seem comfortable only in a knee-chest position in the arms of a caregiver. Vomiting may occur either with the initial painful episode or soon after. Concurrent with vomiting, the child usually has one or more bowel movements, which may vary from thin liquid to formed stools. Within 12 to 24 hours, mucus, blood, or both may be passed per rectum (7).
Only 25% to 65% of patients present with the classic triad of paroxysmal pain, vomiting, and rectal bleeding; most patients develop only colicky abdominal pain and vomiting. (2,4,7). Nonbilious vomiting may become bilious as bowel obstruction progresses. Rectal bleeding is a less constant historic feature and may be found in as few as 40% of patients (8). Frank blood, or blood-streaked stools, may be present in a few hours of the first painful episode. “Currant jelly” stools account for a minority of bloody stools and are typically observed only after prolonged illness (9).
Recognition of the stereotypic history facilitates the diagnosis. However, less-than-classic presentations are frequent and contribute to diagnostic uncertainty and increased morbidity. Among the main factors that contribute to misdiagnosis are altered mental status and listlessness. Valuable time may pass during a well-considered evaluation for altered mental status that is not focused on an abdominal etiology. Altered mental status with intussusception is frequently associated with a prolonged course of illness (10). Furthermore intussusception may be considered late or not at all in patients presenting outside the conventional window of the first 2 years of life. A painless event may occur in 15% of cases (11). Occasionally no blood passes per rectum. The rectal examination early in the course may show show that is normal in appearance, and guaiac testing may be negative.
The vital signs and physical appearance of an affected child may be variable. Most children will be alert and hydrated. Those with advanced disease complicated by either fluid or electrolyte imbalance, or blood loss, may appear less responsive. Not uncommonly, a child with a very brief history of enteric manifestations may be obtunded at presentation. It is speculated the decreased level of consciousness observed in some patients is due to the release of natural endorphins from the intussusceptum.
On inspection, the abdomen may appear scaphoid and the right lower quadrant may seem empty. A sausage-shaped mass, sometimes ill-defined, can be palpated occasionally in the right upper quadrant. Rectal examination may reveal blood, ranging from occult blood noted on guaiac testing to frankly bloody stools. Rarely, rectal prolapse may be noted.
DIFFERENTIAL DIAGNOSIS
Because the signs and symptoms of intussusception overlap with many other clinical diagnoses the differential diagnosis is broad. Conditions that are commonly confused with intussusception include gastroenteritis and constipation. Other entities that should be considered, especially in infants, include malrotation with volvulus, incarcerated hernia, necrotizing enterocolitis, allergic or infectious colitis, and gastroesophageal reflux.
Gastroesophageal reflux, the most common cause of emesis in infants can be misinterpreted as intussusception when it is accompanied by abdominal pain. Bloody stools in infants can also be indicative of underlying allergic colitis; however, patients with allergic colitis generally appear well without vomiting or abdominal pain. Appendicitis can present similarly, with abdominal pain and vomiting and is one of the most challenging entities to differentiate from intussusception.
In patients who present primarily with lethargy, the differential diagnosis is similarly broad and complex. Electrolyte abnormalities, notably hypoglycemia and hyperglycemia should be ruled out. Primary neurologic diseases such as intracranial masses, hemorrhage, ingestion, or seizures need to be considered.
If a right upper quadrant mass is present, other causes of abdominal mass in children in this age should be considered. Wilms tumor is generally characterized as painless and is not usually associated with vomiting. The presence of hematuria would differentiate this from intussusception. Hepatoblastoma can be felt originating from the liver. In patients with neuroblastoma, there can be a history of weight loss, flushing, irritability, diarrhea, and possible electrolyte abnormalities such as acidosis and hypokalemia. If neuroblastoma invades or encroaches upon the spinal cord, lower extremity hyperreflexia and flaccidity may be present.
ED EVALUATION
There are no laboratory tests that can confirm the diagnosis of intussusception, but testing can assist with risk stratification of patients in whom this diagnosis is considered. A stool examination for occult blood has a high benefit-to-cost ratio. A negative guaiac should not be used to exclude the diagnosis, yet a positive stool guaiac should reduce the threshold for further evaluation and management decisions. Other laboratory tests are generally used to exclude other conditions that may have similar presentations. Tests that may help narrow the differential diagnosis include a complete blood count, C-reactive protein, glucose, electrolyte panel, liver function testing, urine analysis, and stool culture. In an ill-appearing child in whom there is concern for underlying peritonitis, sepsis, or perforation, an arterial or venous blood gas, lactate level, and coagulation studies may be helpful. Urine drug screen and computed tomography scan should be considered in patients who have painless intussusception presenting as profound lethargy. The child who appears septic should undergo blood, urine, and cerebrospinal fluid testing.
When intussusception is considered, abdominal radiographs can be utilized to help with risk stratification. Most centers perform two-view radiographs, including supine and left lateral decubitus, but the addition of a third prone view has been argued to further assist in diagnosis (12). Common findings on radiographs that are consistent with intussusception include the presence of a soft tissue mass (typically in the right upper quadrant, often with loss of the visible liver margin), a target sign (concentric radiolucent circles overlying the right kidney), a crescent sign (the cap of the intussusceptum seen within the lumen of the intussuscipiens), paucity of air within the ascending colon or right lower quadrant, and evidence of small bowel obstruction. However, radiographs may be normal, especially early in the course of the disease, or equivocal (13,14). Interobserver reliability among radiologists remains imperfect as well. Thus, negative plain abdominal x-rays do not rule out intussusception and should be followed by ultrasound if intussusception is suspected clinically. The presence of free air precludes reduction by enema.
Children in whom the history and physical examination are highly suggestive of intussusception, should proceed directly to an abdominal ultrasound. Ultrasound is superior to abdominal radiographs, with a sensitivity and specificity that both approach 100%. Ultrasound has been successfully performed by both radiologists and pediatric emergency physicians (15). Ultrasound findings consistent with intussusception include a “target sign” on transverse scan, as well as a “pseudokidney” or “sandwich” sign on longitudinal scan. Ultrasound is the initial diagnostic study of choice for most patients, as it provides a rapid diagnosis without exposure to radiation and allows for evaluation of possible pathologic lead points or alternative diagnoses. Studies have shown that emergency physicians, with limited training, can accurately diagnose idiopathic ileocolic intussusception utilizing bedside ultrasound. If ultrasound is not available, or if the ultrasound results are equivocal, either a barium or contrast enema can be performed, since it is both diagnostic and therapeutic. Abdominal computed tomography scans can accurately detect intussusception, but because of the significant associated radiation exposure involved, ultrasound is preferred when the suspicion for intussusception is high.
KEY TESTING
• Abdominal ultrasound
• Air or contrast enema
ED MANAGEMENT
Most patients who have suspected intussusception require the placement of an intravenous line. These patients should undergo fluid resuscitation as well as correction of any underlying electrolyte imbalances. Although not universally performed, pending imaging procedures, a nasogastric tube should be considered. All patients should be made NPO (i.e., nothing by mouth).
Once intussusception has been confirmed, the patient should be referred for reduction, either via pneumatic or barium enema. Successful reduction rates are variable, but reported to be as high as 80% to 95% (16). Pneumatic enemas are currently favored over barium enemas given the risk of chemical peritonitis if perforation were to occur. Perforation is more likely to occur in patients who are diagnosed later, presumably owing to the higher degree of bowel edema and friability. Surgical reduction is indicated in patients in whom the diagnosis has been delayed or in those in whom reduction cannot be completed by enema. Patients who present with recurrent intussusception should also be considered for surgical reduction, to allow for exploration for a pathologic lead point (17). Surgical options for reduction are at the discretion of the surgeon and include both open and laparoscopic techniques. In patients in whom sepsis, peritonitis, or perforation is suspected, immediate fluid resuscitation, antibiotics, and surgical consultation should be obtained immediately. Antibiotics are not routinely recommended for patients in whom perforation is not suspected.
CRITICAL INTERVENTIONS
• There should be a low threshold for ordering an ultrasound to evaluate for intussusception.
• Children with apparent intussusception require hemodynamic stabilization before undergoing imaging.
• After stabilization, further treatment of intussusception is directed at reduction of the intussusception, most commonly by air or contrast enema.
• Appreciating the importance of timely reduction after the diagnosis is made—“time is bowel.”
DISPOSITION
Well-appearing patients who have undergone successful contrast enema reduction can be discharged after a period of observation and successfully tolerating oral intake (18,19). If the patient continues to appear ill or dehydrated admission is warranted for further resuscitation. If the enema reduction was particularly difficult, indicating delayed diagnosis and more severe ischemia, observation should be considered. Parents should be counseled that in approximately 10% of children (20), intussusception recurs, the majority of which occur in the first 24 hours. Parents should be advised to return to the ED if pain or vomiting recurs.
Common Pitfalls
• Obstacles to accurate diagnosis include failure to recognize the typical history, failure to perform a rectal examination, reluctance to accept the diagnosis in a well-appearing child with a prolonged history, and failure to consider the disease in older children.
• Marked variation from the classic picture may lead to misdiagnosis. The absence of pain, lack of a mass, presence of bright red rectal bleeding, or altered mental status should not dissuade one from considering the diagnosis.
• A normal plain abdominal radiograph in a suspected case of intussusception should not deter performance of further imaging studies such as ultrasound.
ACKNOWLEDGMENT
The authors of this chapter wish to credit the previous edition author, Dr. Adam Singer for is past contributions.
REFERENCES
1. O’Ryan M, Lucero Y, Pena A, et al. Two year review of intestinal intussusception in six large public hospitals of Santiago, Chile. Pediatr Infect Dis J. 2003;22:717–721.
2. Applegate KE. Intussusception in children: Evidence-based diagnosis and treatment. Pediatr Radiol. 2009;S140–S143.
3. Luks FI, Yazbeck S, Perreault G, et al. Changes in the presentation of intussusception. Am J Emerg Med. 1992;10:574–576.
4. Mandeville K, Chien M, Willyerd FA, et al. Intussusception: Clinical presentations and imaging characteristics. Pediatr Emerg Care. 2012;28:842–844.
5. Spiro DM, Arnold DH, Barbone F. Association between antibiotic use and primary idiopathic intussusception. Arch Pediatr Adolesc Med. 2003;157:54–59.
6. Blakelock RT, Beasley SW. The clinical implications of non-idiopathic intussusception. Pediatr Surg Int. 1998;14:163–167.
7. Harrington L, Connolly B, Hu X, et al. Ultrasonographic and clinical predictors of intussusception. J Pediatr. 1998;132:836–839.
8. Bergdahl S, Hugosson C, Lauren T, et al. Atypical intussusception. J Pediatr Surg. 1972;7:700–705.
9. Yamamoto LG, Morita SY, Boychuk RB, et al. Stool appearance in intussusception: Assessing the value of the term “currant jelly.” Am J Emerg Med. 1997;15:293–298.
10. Singer J. Altered consciousness as an early manifestation of intussusception. Pediatrics. 1979;64:93–95.
11. Birkhahn R, Fiorini M, Gaeta TJ. Painless intussusception and altered mental status. Am J Emerg Med. 1999;17:345–347.
12. Roskind CG, Kamdar G, Ruzal-Shapiro CB, et al. Accuracy of plain radiographs to exclude the diagnosis of intussusception. Pediatr Emerg Care. 2012;28:855–858.
13. Applegate KE. Intussusception in children: Imaging choices. Semin Roentgenol. 2008;43:15–21.
14. Weihmiller SN, Buonomo C, Bachur R. Risk stratification of children being evaluated for intussusception. Pediatrics. 2011;127(2):e296–e303.
15. Riera A, Hsiao AL, Langhan ML, et al. Diagnosis of intussusception by physician novice sonographers in the emergency department. Ann Emerg Med. 2012;60:264–268.
16. Daneman A, Navarro O. Intussusception. Part 2: An update on the evolution of management. Pediatr Radiol. 2004;34:97–108.
17. Hsu WL, Lee HC, Yeung CY, et al. Recurrent intussusception: When should surgical intervention be performed? Pediatr Neonatol. 2012;53:300–303.
18. Herwig K, Brenkert T, Losek JD. Enema-reduced intussusception management, is hospitalization necessary? Pediatr Emerg Care. 2009;25(2):74–77.
19. Adekunle-Ojo A, Craig A, Ma L, et al. Intussusception: Postreduction fasting is not necessary to prevent complications and recurrences in the emergency department observation unit. Pediatr Emerg Care.2011;27:897–899.
20. Bajaj L, Roback MG. Postreduction management of intussusception in a children’s hospital emergency department. Pediatrics. 2003;112:1302–1307.