Intussusception in Childhood
September 1, 2000
Intussusception in Childhood
Authors: Estevan A. Garcia, MD, Pediatric Emergency Medicine Fellow, University of Texas Southwestern Medical Center, Children’s Medical Center, Dallas, TX; and Robert A. Wiebe, MD, FAAP, FACEP, The Sarah M. and Charles E. Seay Distinguished Chair; Professor; Director of Pediatric Emergency Medicine, University of Texas Southwestern Medical Center at Dallas, TX.
Peer Reviewer: Daniel M. Cohen, MD, FAAP, FACEP, Pediatric Emergency Medicine Director, Urgent Care, Children’s Hospital, Columbus, OH.
Though it occurs infrequently, intussusception must be considered as a possible cause of abdominal pain in the pediatric age group. Since most children with intussusception are younger than 1 year of age and non-verbal, the clinician must maintain a high index of suspicion for this entity in any infant who presents with vomiting, irritability, and/or lethargy. It is the most common cause of intestinal obstruction in children between 3 months and 6 years of age.1 Intussusception is defined as an invagination or telescoping of a segment of intestine into an adjacent portion of bowel. The goal of the examining physician is early and accurate recognition of this condition, since a misdiagnosis or delay in diagnosis may result in the need for surgical reduction or intestinal resection.2
Intussusception is a true pediatric emergency that may pose a diagnostic challenge for even the most experienced physician. Unfortunately, a thorough physical exam and plain abdominal radiographs often do not provide sufficient information to reliably eliminate this disease entity from the differential diagnosis of pediatric abdominal pain. The diagnosis and management of intussusception has evolved over time as surgeons and radiologists attempt to improve the accuracy of diagnosis and the ease and effectiveness of reduction.3 All physicians caring for infants and children should maintain a high level of suspicion for intussusception as a cause for pediatric abdominal pain.
— The Editor
Epidemiology
Intussusception has been recognized for hundreds of years, but was not accurately described until 1793, when John Hunter described an ileocolic intussusception in a 9-month-old infant at autopsy.4 While most studies examining the prevalence of intussusception are more than 30 years old, the rate constantly varies between 1.5 and 4.3 cases per 1000 live births.5 Most recently, approximately 2.4 cases per 1000 live births was reported in the United States.5 There also may be annual or seasonal fluctuations secondary to environmental influences, but this finding has not been consistently supported in the literature.6
The condition can occur at any age, but it is estimated that more than 50% of cases present in children younger than 1 year of age, and most commonly between those 5 and 9 months of age.2,5,7 Fewer than 10% of cases occur in children older than 5 years of age. Intussusception has been reported neonatally and prenatally as a cause of intestinal atresia.8 There is a 2:1 male predominance ratio.9 The literature has not supported any familial or ethnic tendency for intussusception, though some investigators have reported possible associations.9 Contrary to what was once believed, intussusception occurs in both well-nourished and malnourished children.5,9
Morbidity and Mortality
Intussusception usually was fatal prior to the 20th century. The introduction of contrast enemas has reduced mortality to less than 10%, and early recognition with prompt intervention has reduced mortality to less than 1%.5 While the number of deaths due to intussusception has declined over the last several years, avoidable deaths continue to occur.10 The highest morbidity and mortality is found in older children with small bowel lesions that result in pathologic lead points and delayed diagnosis.5
Pathophysiology
Intussusception occurs when a portion of the intestine prolapses into itself. This "telescoping" process starts as the lead point of the prolapsed segment, the intussusceptum, slides by peristaltic contraction into the receiving segment of the intestine, the intussuscipiens. The progressing prolapsed segment will compress mesenteric vessels supplying the intussusceptum. This process limits blood flow, leading to obstruction, strangulation, and if uninterrupted, bowel necrosis. Necrosis begins at the outer layer of the intussusceptum and extends from the apex proximally.11 The intussuscipiens, or receiving segment of intestine, may become ischemic secondary to pressure from the intussusceptum, which may then perforate into the abdominal cavity. Bowel compromise usually is seen within 6-12 hours of the onset of symptoms.12
The disease process usually is classified according to the site of intussusceptum and intussuscipiens. Approximately 90% of cases are ileocolic, originating in the terminal ileum and extending through the ileocecal valve to the proximal colon.13 The intussusceptum may extend the entire length of the colon. Eighty percent of ileocolic intussusceptions have their apex in the ascending colon.14
Etiology
The vast majority of cases of intussusception are idiopathic, without an identifiable underlying cause.5,6,15 Lymphoid hyperplasia is the only consistent finding in approximately 90% of cases.5,7 Ravitch suggested that virus-induced lymphoid hyperplasia may be a significant factor in the development of intussusception since there is a ring of lymphoid tissue which surrounds the ileocecal valve, the most common anatomic lead point for intussusception.16 This tissue is much more pronounced in children younger than 2 years of age. Certain viruses have been implicated as a possible cause of intussusception, including adenovirus, echovirus, coxsackie virus, and rotavirus.16,17
During the summer of 1999, an association between the rotavirus vaccine, Rotashield, and the subsequent development of intussusception was recognized. The Centers for Disease Control and Prevention recommended postponement of vaccine administration, and revealed that 15 cases of intussusception following the first dose of the vaccine had been reported to the Vaccine Adverse Event Reporting System.18 The rhesus rotavirus vaccine-tetravalent (RRV-TV) was voluntarily withdrawn from the United States by the manufacturer on Oct. 16, 1999. The vaccine is no longer available in any part of the world. The Advisory Committee on Immunization Practices concluded that intussusception occurs with significantly increased frequency in the first 1-2 weeks after immunization with RRV-TV, especially after the first dose.18 No causal effect between the vaccine and the subsequent development of intussusception has been found. Vaccinated children who remain well carry no increased risk of intussusception.
Pathologic lead points consistently have been demonstrated in approximately 10% of cases of intussusception.6,7,16,17 The vast majority of these patients are older than 2 years of age. The most common lead point is a Meckel’s diverticulum, but polyps, appendicitis, neoplasms, and foreign bodies also can serve as lead points.19 Lead points are more common in patients with cystic fibrosis, Henoch-Schonlein purpura (HSP), and Peutz-Jeghers syndrome.19,20
HSP is a small vessel systemic vasculitis that requires special consideration in any discussion of intussusception. One group reviewed the intra-abdominal manifestations of HSP and found intussusception to occur in approximately 3.5% of patients.21 Intussusception can develop at any time during the illness, though it is uncommon in patients younger than 2 years of age.22 Since HSP often is associated with abdominal pain and rectal bleeding, the clinicians must be cautious not to miss this serious complication.
Differential Diagnosis
The clinical presentation of a child with intussusception can be confusing and is generally nonspecific. Similar presenting symptoms can be seen with all of the following disease processes: gastroenteritis, colitis, colic, incarcerated hernia, appendicitis, inflammatory bowel disease, trauma, polyps, and Meckel’s diverticulitis. Previous studies have reported that up to 60% of cases of intussusception are initially misdiagnosed.2,7 Gastroenteritis most commonly is confused with intussusception.23 Because the majority of patients are too young to communicate or cooperate with an exam, the nonspecific signs and symptoms of vomiting, irritability, anorexia, and lethargy initially may be attributed to other diagnoses.
Signs and Symptoms
The classic symptom triad of intermittent abdominal pain, red currant jelly stools, and vomiting, when present, facilitates the diagnosis. (See Table 1.) Unfortunately, the majority of patients do not present with classic symptoms. Bruce and colleagues found that only 21% of patients presented with the classic triad.6 In this series of 583 patients, 70% had two of these symptoms, while 9% had only one symptom.6 Colicky abdominal pain, the most consistent finding, occurs in 80-95% of patients.20 Intermittent abdominal pain is, by far, the most significant symptom and, when present, should be taken very seriously. The pain, described as episodic, persists for 4-5 minutes. The infant may pull his knees up to his chest while screaming or crying. Pain may recur every 5-30 minutes, and children can appear normal between episodes. Researchers found that 28% of patients who were diagnosed with intussusception initially had a normal physical exam.23
| Table 1. Clinical Features of Intussusception |
| • Colicky abdominal pain |
| • Vomiting (bilious/non-bilious) |
| • Irritability |
| • Bloody stools (occult/gross) |
| • Abdominal mass |
| • Diarrhea/fever |
| • Altered mental status |
The vast majority of patients experience vomiting secondary to obstruction. Bruce et al found that 70% of patients had vomiting.6 Initially, the emesis is non-bilious, but as the obstruction progresses, it can become bilious or even feculent. Mucoid, bloody stool is not considered a reliable sign, especially if symptoms are of short duration. Hematochezia was the cardinal symptom in only 8% of patients.6 It is important to realize that grossly bloody stools are a late sign of intussusception and are evidence of bowel ischemia. Occult blood is much more common, even if patients are asymptomatic at time of presentation.5 Patients also may complain of fever and diarrhea, but these are not frequent findings.
A palpable, sausage-shaped abdominal mass is present in 60-85% of cases of intussusception.20 The mass usually lies in the area of the hepatic flexure, but may occur anywhere along the course of the bowel.24 Dance’s sign, which is a concavity in the right lower quadrant due to absence of underlying bowel, also may be present.24,25 Ileocolic intussusception usually will have a palpable mass in the right upper quadrant and a concavity in the right lower quadrant, since the telescoping process pulls the bowel structures upward in the abdomen. Even the most experienced physician may find it difficult to palpate a mass in a crying infant with abdominal pain, but once the child is adequately sedated or under general anesthesia, a mass is almost always palpable unless spontaneous reduction occurs during induction.
Reports of behavioral changes as a presenting symptom of intussusception have been well documented in the literature.26,27 The exact mechanism for lethargy is not well understood. One researcher reported lethargy as the prominent symptom in 19 of 37 patients.28 Tenenbein and associates theorized that release of endogenous opioids secondary to ischemia of the bowel may cause the decreased level of consciousness.29 He described a case of a 10-month-old infant presenting with coma and miosis who responded to repeated injections of naloxone.29 A more recent study examining the levels of plasma beta-endorphins and intussusception did not support the previous findings.30 Most authors believe that intussusception should be included in the differential of any child presenting to the emergency department (ED) with altered mental status. The associated presence of gastrointestinal symptoms, particularly vomiting, also should increase the suspicion of the examining physician.
Imaging Aids to Diagnosis
Plain Radiography. The clinical diagnosis of intussusception remains challenging, and clinicians often must rely on imaging procedures to assist with the diagnosis. Plain abdominal radiographs have been used for many years to aid in the diagnosis of intussusception. However, no plain radiograph findings can be considered pathognomonic or completely reliable in supporting or ruling out the diagnosis of intussusception. The first reported radiographic diagnosis was in 1914.31 Suggestive signs on plain radiograph include: soft-tissue mass (the most common finding), absence of fecal gas and stool, loss of visualization of the tip of the liver, and paucity of bowel gas.32,33 (See Figure 1.) The most specific radiologic findings when present are: the target sign (two concentric, circular, radiolucent lines caused by mesenteric fat, to the right of the spine and superimposed on the kidney) and the meniscus sign (a crescent of gas within the colonic lumen that outlines the apex of the intussusception).34,35 One study found that the target sign was the most common finding on plain radiographs, being present on approximately 68% of films.35 Another group found the best positive predictors of intussusception were a soft-tissue mass and sparse large bowel gas, while the presence of cecal stool or gas made a diagnosis of intussusception unlikely.36
The accuracy of plain films in the diagnosis or exclusion of intussusception ranges from 40% to 90%.32 While the value of plain abdominal radiography in the diagnosis of intussusception is controversial, many authors still feel that it does have a role in certain situations. One study states that when clinical suspicion is low and vague abdominal symptoms predominate, plain radiography may be helpful.32 If clinical suspicion is high and symptoms are of short duration, a more definitive and sensitive imaging study is mandatory.31,32 Plain radiography also may have a role in eliminating free air as a possibility in children with prolonged symptoms in which peritonitis is clinically evident. The "presence of free air" is always a contraindication to enema reduction.31
Ultrasound. Ultrasound, because of its wide availability, lack of ionizing radiation, and accuracy of nearly 100% in identifying intussusception, has become the noninvasive, diagnostic procedure of choice in some institutions.37 Swischuk and colleagues performed the first prospective series on the use of ultrasound in patients with suspected intussusception in 1985.38 Since that time, the sensitivity, specificity, and negative predictive value of ultrasonography have been examined repeatedly in the literature. One study found that ultrasound had a sensitivity of 98.5% and a specificity of 100% in a retrospective review of 163 children with clinical suspicion of intussusception.39 Another study found that ultrasound had a sensitivity of 100%, specificity of 93%, and a negative predictive value of 100%.40
The ultrasonographic diagnosis of intussusception may be made by both axial and longitudinal scans. The longitudinal scan may show the mesentery (hyperechoic bands) on one or both sides of the central limb of the intussusceptum (hypoechoic bands), which is known as the sandwich sign.32,38-40 The pseudokidney sign occurs if the mesentery is seen on only one side of the intussusceptum. The axial scan image is described as a target sign or doughnut, which is caused by a hypoechoic ring surrounding a hyperechoic center.32,38,39,40 Sonography may also aid in identification of lead points, such as Meckel’s diverticulum.5 Ultrasonography is not only useful in the diagnosis of intussusception, but also in evaluation of the acute abdomen by identifying other intra-abdominal lesions distinct from intussusception. Daneman and Altan believe that, as more radiologists become comfortable with relying solely on sonography for the diagnosis and exclusion of intussusception, enemas can be limited to a therapeutic intervention only.31
In older children, or in children with HSP where a pathologic lead point is suspected, ultrasonography may be the diagnostic procedure of choice.41,21 Since intussusception with a pathologic lead point is unlikely to resolve with enema reduction, diagnosis by ultrasonography should direct the clinician to seek definitive surgical reduction.
Computed Tomography and Magnetic Resonance Imaging. Computed tomography (CT) may be useful in the evaluation older children and adults. Beyond infancy, intussusception more commonly results from a pathologic lead point which may be readily identified by CT.42 CT also may have a role in identifying free air and localizing a perforation. Characteristic CT findings for intussusception are three concentric circles, of which the center is a soft-tissue mass, possibly with oral contrast, surrounded by a ring of mesentery.42 This ring is, in turn, surrounded by a second soft-tissue ring with or without contrast.42
The role of magnetic resonance imaging (MRI) in the acute abdomen has not been established. Longer scan times and motion artifact limit its usefulness in the evaluation of intussusception as well as other acute intra-abdominal processes.
Diagnostic Enema. Barium enema (BE) has been the gold standard for diagnosing intussusception for many years. The classic signs of intussusception on BE are the meniscus sign and the coiled spring sign. (See Figures 2 and 3.) The meniscus sign is made by the apex of the intussusceptum protruding into a column of contrast, and the coiled spring sign is produced when swollen bowel representing the returning limb of the intussusceptum is outlined by contrast in the lumen of the colon.32 Barium is contraindicated in patients with suspected bowel perforation, peritonitis, or shock. Whenever there is a prolonged course, significant rectal bleeding, or copious current jelly stools, or an infant who appears toxic, BE should be avoided.
Management
All patients with suspected intussusception should have intravenous access established and receive adequate volume replacement. One study found that 20% of patients who died of intussusception were not fluid resuscitated sufficiently.10 Bowel ischemia can lead to necrosis and release of mediators of inflammation and shock. Third spacing of fluids can occur, and isotonic fluid volume resuscitation is an important part of emergency management of patients with signs of shock, peritonitis, perforation, or abdominal distention. A nasogastric tube should be placed in all children with significant abdominal distention or protracted emesis. While the well-appearing child may not benefit from routine laboratory examination, baseline electrolytes, glucose, complete blood count, and arterial blood gases are indicated in any ill-appearing child. Routine antibiotic administration is not necessary in the care of children with intussusception, but should be considered for patients with suspected peritonitis. It is important to monitor vital signs closely because therapeutic options differ based on the patient’s clinical condition. Surgical consultation should be requested early; ideally, a pediatric surgeon should be available prior to the non-operative procedure. Non-operative reduction is recommended only if surgical facilities and resources are available should complications occur. The child who is toxic or ill appearing requires immediate surgical exploration.
Nonsurgical reduction of intussusception has been used since the early 1800s. One researcher reported a series of reductions by hydrostatic pressure in 1876.8 It was not until the 1940s, when Ravitch and McCune published scientifically tested and standardized methods of fluoroscopically guided enema therapy, that this method became more accepted.32 Since 1970, nonoperative reduction has become the preferred management of intussusception. There is no accepted recommendation for the number of reduction attempts, use of sedation, or use of transabdominal manipulation.32 There are currently three types of contrast material available for attempted reduction: barium, water-soluble media, and air.
Water-soluble contrast has been used to avoid the possibility of chemical peritonitis, which is caused by barium if perforation should occur. It is believed that the complications that occur from barium leakage are less likely to occur with water-soluble media. The reduction rate and perforation rate are similar to those of other contrast materials, but experience is limited.32
Barium enema successfully reduces approximately 80% or more of cases.2 Reduction is successful when there is free reflux of barium into the small bowel without any residual filling defects and when the patient shows clinical improvement.
While the type of media used varies by institution, there is a growing body of evidence that supports the use of air as the enema of choice for reduction. Air enema reduction was introduced in China more than 30 years ago and has been used extensively since, with successful reduction achieved in more than 95% of cases.43 This method has become more widespread in the United States in the past decade. One group reports that air reduction is quicker, safer, and more effective than barium enema.44 (See Table 2.) Reduction by air enema appears to be more successful if symptoms are present for less than 12 hours, no rectal bleeding is noted, the small bowel is not obstructed, a palpable mass is present, and the child is well hydrated.44 Air enema is considered successful if air passes freely to the small intestine.
| Table 2. Air vs. Barium Enema | ||
| Barium | Air | |
| Radiation exposure | Less | More |
| Reduction | 80% | 95% |
| Perforation | < 1% | 3% |
| Complication | Chemical peritonitis | Tension pneumoperitoneum |
Complications and Perforation
Perforation of the intestine has been shown to occur as a result of both air and barium enema reductions. Daneman and associates compared the rates of perforation with barium (0.7%) and with air (2.8%) during reduction of 14 children, placing seven in each group.45 Perforations occurred in younger patients with longer duration of symptoms. The barium group all required resection resulting in longer operative times, while the air group tended to have smaller perforations and less soiling of the peritoneum.45 Escape of barium into the peritoneal cavity easily can be visualized fluoroscopically. Free air in the peritoneal cavity may present as a tension pneumoperitoneum. Immediate decompression with an 18-gauge needle is required if a tension pneumoperitoneum develops.
Surgical Reduction
Operative reduction is the procedure of choice for patients with signs of peritonitis, free air on plain films, and for those who fail non-surgical reduction. Recurrent intussusception is often considered an indication for surgical resection. At laparotomy, the intussusception is "milked" back by compression to its apex. The bowel is then carefully inspected for any signs of perforation or necrosis. Resection is reserved for non-viable bowel with evidence of infarction, perforation, or presence of a pathologic lead point.6 Failure to manually reduce the intussusception is another indication for resection. A late complication of surgical reduction is intestinal obstruction from adhesion, which is not seen in enema reduction, unless perforation occurs.
Post-Reduction Management
The disposition of an infant or child that has undergone successful reduction of an intussusception is controversial. Some institutions discharge the patients home after a brief observation period in the ED, while others hospitalize all patients for a minimum of 24 hours. Recurrent intussusception occurs in about 4% of cases, with rates varying from 10% after radiological reduction to 1% after surgical reduction.5 Recurrences usually are detected within hours to days following contrast reduction, but can be delayed after surgical reduction. Peak incidence of recurrence is during the eighth month following reduction.5 In children with a suspected lead point, a CT or Meckel’s scan may be preformed to eliminate the possibility of a mass that requires surgical intervention.41
Conclusion
The early diagnosis of intussusception remains a challenge for physicians since signs and symptoms are often misleading and nonspecific. One must always consider intussusception in infants and children with mental status changes such as lethargy and/or irritability, and gastrointestinal symptoms such as vomiting and abdominal pain. Prompt diagnosis and enema reduction can reduce morbidity and mortality significantly.
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