A 24-month-old male came to the emergency room with a 12 hour history of colicky abdominal pain every 15-20 minutes. He is normal between episodes but has decreased overall intake. He has non-bilious emesis during some of these episodes.
He has had several normal stools which do not contain mucous or blood. The rest of his history is unremarkable.
The pertinent physical exam shows a healthy boy with normal growth parameters. His abdomen shows no distension, nor is tympanetic. He has normal bowel sounds. His abdomen is soft, without pain and with no organomegaly or masses palpable. His genitourinary examination is normal.
At this time the differential diagnosis that was discussed was gastroenteritis versus intussusception.
His radiologic evaluation began with a plain film of his abdomen which showed a non-obstructed gas pattern and a suspicious soft tissue mass in the right lower quadrant.
The ultrasound confirmed the diagnosis of intussusception at the level of the cecum just below the hepatic flexure. During the examination he was noted to draw-up his legs to his abdomen in episodic pain.
The intussusception was easily reduced by air contrast enema. He was admitted for 20 hours of follow-up and was eating and drinking normally at discharge.
Figure 19 – Supine AP radiograph of the abdomen showing an unremarkable bowel gas pattern and suggests a mass in the right lower quadrant.
Figure 20 – Ultrasound image of the right lower quadrant, obtained transversely through the colon, showing a colonic mass in the ascending colon, the so-called “target sign” representing intussusception.
Figure 21 – Ultrasound image of the right lower quadrant, obtained longitudinally through the colon, showing a colonic mass in the ascending colon, the so-called “pseudo-kidney sign” representing intussusception.
Figure 22 – Fluoroscopic spot film obtained during an air enema showing an intussusception near the hepatic flexure. The “coiled-spring” appearance of the intussusception can be seen.
Intussusception happens when one segment of the gastrointestinal tract telescopes into an adjacent segment. The outer receiving segment of bowel is known as the intussuscipiens and the inner inverting segment is known as the intussusceptum.
It occurs most often in children between 2 months to 5 years, with a peak incidence between 4-10 months. Males are more often affected than females by 3:2. It also occurs more often after abdominal operations.
It is the second most common acute abdominal emergency in children after appendicitis.
in adults ~80% have an underlying cause or lead point such as a polyp, tumor, fibrosis, endometriosis, etc.. The cause is usually idiopathic in children (95%) but it is hypothesized that In children is caused by a viral induced edema of the Peyer’s patches in the ileum that serves as a lead point, but this hypothesis has not been confirmed. It commonly occurs near the ileocecal valve.
Unequal longitudinal forces in the bowel then cause the bowel wall to invaginate into the lumen. The intussusceptum is propelled onwards by peristalsis with more bowel becoming involved. Blood vessels and mesentery also become involved with resulting edema, all of which results in intestinal obstruction.
Pressure in the bowel wall increases with impedence of venous outflow and followed by arterial inflow, which again leads to edema and more intestinal obstruction.
Early diagnosis and treatment is necessary to prevent these physiologic changes from progressing to bowel infarction and perforation.
If not treated, intussusception can be fatal in 2-5 days.
In the radiology suite, diagnosis and definitive treatment often occur concurrently.
- Plain film was first used to diagnose intussusception in 1941. Early on there are few radiological changes seen. With time, soft tissue densities or absence of air in the right upper and lower quadrants can be seen.
Small bowel dilitation and air fluid levels may also be seen in more advanced cases. If the intussusception has progressed to perforation, then free air may be seen.
Although plain films are useful, they lack sensitivity and many false negatives can occur.
- Ultrasound was first used to diagnose intussusception in the 1980s.
Ultrasound is fast, non-invasive, easy to perform and reproducible, with a high rate of sensitivity and specificity in experienced hands. The classic findings are a doughnut or target sign with concentric rings formed by the intussusceptum.
The pseudo-kidney sign on longitudinal imaging shows multiple thin parallel stripes of varrying echogenitiy .
- Barium or air enema is one of the most reliable tests for intussusception in children. It is both diagnositic and therapeutic.
The pediatrician must work with the radiologist and surgeon, to clinically stabilize the child before the procedure and to plan for treatment of possible problems such as perforation.
Radiologic reduction should be attempted unless there are signs of peritoneal irritation and is successful in >90% of cases.
The procedure involves placing a catheter without balloon inflation into the rectum and taping the buttocks together. Barium in introduced via a reservoir suspended ~3 feet over the child.
Traditionally 3 attempt, each lasting 3 minutes are made to reduce the intussusception.
Fluoroscopy confirms the intusccusception and monitors the reduction. The intussusception is reduced when there is free flow of barium or air into the terminal ileum.
Air can be used instead of barium by introducing air up to a pressure of 120 centimeters of water.
If air is used, the pressure can be maintained for 3 minutes before being released. The air enema reduction is also attempted 3 times before surgery is indicated.
Some centers will attempt more than 3 times to reduce the intussusception if progress is being made as the patient will be going to the operating room if the enema fails.
The main risk of the procedure is causing perforation of the bowel or unmasking a pre-existing perforation of bowel and subsequent barium peritonitis or tension pneumoperitoneum. Air has less risk of perforation than barium and is less messy.
- Computed tomography and magnetic resonance imaging are not often used in children as the diagnosis is often made by ultrasound or enema. These modalities are often used in adults to diagnose the underlying pathology of the intussusception.
After reduction, the children are monitored for several hours for reoccurrance (3-10%) and then are dischaged home. Reoccurence after the peri-reduction period is uncommon.
Children with reoccurence or who are older than the typical age should be evaluated for possible underlying pathology.
Causes in descending order are: Meckel’s diverticulum, polyp, gastrointestinal duplication, hemangioma, suture line, appendix, tumors and ectopic pancreas.
Intussusception has a classic clinical triad of severe, colicky, intermittent abdominal pain, red “currant jelly” stool (because of sloughed intestinal mucosa and blood) and a palpable mass in the right lower quadrant or mid-upper abdomen.
This occurs only in 50% of patients though.
The child will often flex the knees and hips during the pain. The pain often becomes more frequent with time. Stool passage may be normal at first then turn bloody after hours to days. With time, pallor, diaphoresis and apathy in the child ensue.
Presentations of Intussusception include:
- Abdominal pain – 85%
- Emesis – 75%
- Bloody stools – 60%
- Young infants may present with “intussusception encephalopathy” or lethargy, obtundation, and even coma
Questions for Further Discussion
1. How long after the onset of symptoms should radiologic intervention not be attempted?
2. How much does ultrasound contribute to the management of patients with suspected intussusception?
3. What are teh contraindications to radiologic reduction of intussusception?
To Learn More
To view pediatric review articles on this topic from the past year check PubMed.
Information prescriptions for patients can be found at Pediatric Common Questions, Quick Answers for this topic: Acute Abdominal Pain.
To view current news articles on this topic check Google News.
Rudolph CD, et.al. Rudolph’s Pediatrics. 21st edit. McGraw-Hill, New York, NY. 2003:1407-08.
Byrne AT, Geoghegan T, Govender P, Lyburn ID, Colhoun E, Torreggiani WC. The Imaging of Intussusception. Clin Radiol. 2005;60(1):39-46.
Donna M. D’Alessandro, MD
Associate Professor of Pediatrics, Children’s Hospital of Iowa
August 15, 2005