Intussusception - Diagnosis and Air Enema Reduction

Key Points

• The classic triad is absent in many children; episodic pain and unexplained lethargy can be enough to trigger evaluation.
• Ultrasound is the preferred initial imaging test for suspected intussusception.
• Air or hydrostatic enema is first-line therapy for stable ileocolic intussusception without perforation or peritonitis.
• Surgical backup should be available during reduction.
• Peritonitis, perforation, shock, failed enema reduction, or a pathologic lead point favors surgery.
• Older age or recurrent intussusception increases concern for a structural lead point.
• Recurrence can occur after successful reduction, so discharge counseling matters.

Algorithm

1. Recognize intermittent severe pain, vomiting, lethargy, or bloody stool and examine for peritonitis and shock.
2. Keep the child NPO, establish IV access, provide analgesia and resuscitation as needed.
3. Obtain abdominal ultrasound as the preferred diagnostic study.
4. Call pediatric surgery early, especially for prolonged symptoms or ill appearance.
5. If stable without perforation or peritonitis, proceed to image-guided air or hydrostatic enema reduction.
6. Confirm successful reduction clinically and radiographically.
7. Operate when enema is contraindicated, unsuccessful, or a lead point or necrotic bowel is suspected.
8. Observe after reduction and discharge only with reliable recurrence instructions and follow-up.

Clinical Synopsis & Reasoning

Intussusception most commonly occurs between about 6 months and 3 years of age. The bowel invaginates into an adjacent segment, dragging mesentery and compromising venous and lymphatic drainage; untreated disease can progress to edema, ischemia, necrosis, perforation, and shock. The classic triad of colicky pain, a palpable sausage-shaped mass, and currant-jelly stool occurs in a minority of patients and should not be required for diagnosis. Many children present with intermittent episodes of intense crying, drawing the legs up, vomiting, and then appearing surprisingly well between episodes. Lethargy can be prominent and occasionally is the main presenting symptom.

As obstruction progresses, vomiting can become bilious, abdominal distention increases, and stools may contain blood and mucus. A palpable mass is often in the right upper or mid abdomen. Peritonitis, free intraperitoneal air, severe shock, or a rigid abdomen suggests perforation or advanced ischemia and changes management. Ultrasound is the first-line imaging test and typically shows a target or doughnut sign in transverse view and a pseudokidney appearance longitudinally. It can also assess free fluid and bowel perfusion. Plain radiographs are less sensitive and are mainly helpful when perforation or another obstruction is suspected.

Most ileocolic intussusceptions in young children are idiopathic and may follow viral lymphoid hyperplasia. A pathologic lead point becomes more likely with older age, recurrent episodes, small-bowel intussusception, or unusual location. Meckel diverticulum, intestinal polyp, lymphoma, duplication cyst, and IgA vasculitis are examples. The differential includes gastroenteritis, appendicitis, volvulus, incarcerated hernia, constipation, and testicular or ovarian pathology. Bloody stool in an ill child should never be dismissed as routine gastroenteritis without considering ischemic bowel.

Treatment Strategy & Disposition

Stabilize first. Keep the child NPO, establish IV access, provide isotonic fluid for dehydration or shock, and give analgesia and antiemetic treatment. Surgical consultation should occur early, especially when symptoms are prolonged or the child is ill. If ultrasound confirms ileocolic intussusception and there is no peritonitis, perforation, or profound instability, image-guided pneumatic air enema or hydrostatic contrast/saline enema is the preferred initial reduction technique. Air enema is commonly used because it is effective, fast, and limits peritoneal contamination if perforation occurs. The procedure should be performed where pediatric surgical rescue is available because perforation, though uncommon, is a serious complication.

Successful reduction is shown by passage of air or contrast into the small bowel and disappearance of the intussuscepted mass. The child's pain often improves dramatically. Some centers repeat enema reduction after an incomplete first attempt when the child remains stable and there are no perforation signs. Surgery is indicated for perforation, peritonitis, failed nonoperative reduction, an unstable child who cannot safely undergo enema, or a suspected pathologic lead point requiring operative treatment. Bowel resection is necessary when necrosis or an irreducible lead point is found.

After successful reduction, observe for return of symptoms and ability to tolerate intake. Recurrence occurs in a minority of children, most often within the first day or two but possible later. Routine admission after every uncomplicated successful reduction is not universally required; disposition depends on age, duration of symptoms, recurrence risk, time of day, reliability of follow-up, and local practice. Families must receive specific recurrence instructions because a child can look completely normal between recurrent episodes.

Epidemiology / Risk Factors

• Intussusception is one of the most common abdominal emergencies in infants and toddlers.
• Most pediatric cases are ileocolic and idiopathic.
• Cases often cluster with viral illnesses, reflecting lymphoid hyperplasia as a possible trigger.
• Pathologic lead points are more common in older children than in typical infant disease.

Investigations

When to Call Surgery Early

Pharmacology

Prognosis / Complications

• Nonoperative reduction succeeds in most uncomplicated ileocolic cases when performed promptly.
• Recurrence occurs in a minority after successful enema and is usually treatable with repeat reduction if no new contraindication develops.
• Perforation and bowel necrosis increase morbidity and can require resection.
• Long-term prognosis after uncomplicated reduction is excellent.

Patient Education / Counseling

• Explain that symptoms can disappear completely between episodes and still represent recurrence.
• Return immediately for renewed severe episodic pain, repeated vomiting, blood in stool, marked lethargy, or abdominal swelling.
• After successful reduction, follow local instructions about diet and observation.
• If a lead point was identified, explain the need for surgical or specialty follow-up.
• Parents should know that recurrence is possible but does not mean the first reduction was performed incorrectly.

Notes

Intussusception is a condition in which the child can look much better than the bowel. The alternating pattern of severe pain and normal behavior is a diagnostic clue rather than reassurance. Lethargy without a clear explanation is another important presentation, especially in infants who cannot localize or describe pain.

Enema reduction is successful precisely because it treats the mechanical problem directly. Analgesics, fluids, and antiemetics support the child but do not reduce the bowel. When perforation, ischemia, or a lead point is suspected, the strategy changes from radiologic reduction to operative control, so repeated assessment for those features is essential.

References

1. American College of Radiology Appropriateness Criteria: Abdominal Pain in Children, Suspected Intussusception — Link
2. American College of Radiology evidence review: Pediatric intussusception — Link