Pediatric Imaging

ACR Guide: What Is the Best Initial Imaging for Suspected Pediatric Intussusception?

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ACR Guide: What Is the Best Initial Imaging for Suspected Pediatric Intussusception?

A 2-year-old boy presents to the emergency department with his parents on a Tuesday evening. He has been having episodes of intense, colicky abdominal pain for the past 12 hours, during which he pulls his knees to his chest and cries inconsolably. Between these episodes, he is unusually lethargic. His mother reports one diaper with bloody, mucoid stool she describes as looking like “currant jelly.” Faced with this classic presentation, you suspect intussusception and need to decide on the most appropriate initial imaging study. This article provides a detailed clinical workflow for this specific scenario, explaining why the American College of Radiology (ACR) Appropriateness Criteria rates an abdominal ultrasound as ‘Usually Appropriate’ as the first-line imaging test.

Who Fits This Clinical Scenario for Suspected Intussusception?

This guidance applies to a specific pediatric patient: a child presenting with acute abdominal pain where intussusception is a primary clinical suspicion. The classic patient is between 6 months and 3 years of age, the peak incidence range for idiopathic ileocolic intussusception. The presentation often includes intermittent, severe, colicky pain, with periods of lethargy or normal behavior in between.

While the classic triad of colicky pain, a palpable sausage-shaped abdominal mass, and currant jelly stool is highly suggestive, it is present in a minority of cases. A high index of suspicion based on the pattern of pain, lethargy, emesis (which may become bilious), or bloody stools is sufficient to place a patient in this clinical scenario. This workflow is intended for the initial diagnostic imaging step in a previously healthy child without a history of abdominal surgery.

It is crucial to distinguish this presentation from similar but distinct clinical situations that follow different diagnostic pathways:

  • Suspected Constipation: If the pain is less severe, more chronic, and associated with a history of infrequent or hard stools, the workup shifts. This scenario is covered in the ACR variant for suspected constipation.
  • Suspected Surgical Complication: In a child with a history of abdominal surgery, acute pain and obstructive symptoms raise concern for adhesions or other post-operative issues, which may alter the initial imaging choice.
  • Suspected Necrotizing Enterocolitis: In a premature or medically fragile infant presenting with abdominal distension, bloody stools, and signs of sepsis, the primary concern is necrotizing enterocolitis, a distinct and urgent diagnosis with its own imaging protocol.

What Diagnoses Are You Working Up with This Imaging?

When ordering initial imaging for suspected intussusception, the primary goal is to confirm or exclude this diagnosis, but the study can also reveal common mimics. The differential diagnosis guides the interpretation of the imaging findings.

Ileocolic Intussusception
This is the most common type of intussusception in children and the principal diagnosis to rule out. It occurs when a segment of the ileum telescopes into the colon, leading to venous and lymphatic congestion, edema, and eventual arterial compromise, which can cause bowel ischemia, perforation, and peritonitis. The imaging study is designed to directly visualize this telescoping bowel.

Mesenteric Adenitis
Inflammation and enlargement of the mesenteric lymph nodes, often following a viral infection, is a frequent mimic of both intussusception and appendicitis. Children present with genuine abdominal pain, but the underlying cause is self-limited and medically managed. Ultrasound is effective at identifying enlarged lymph nodes in the absence of an intussusception, clarifying the diagnosis.

Gastroenteritis
Viral or bacterial gastroenteritis is a very common cause of abdominal pain, vomiting, and sometimes bloody stool in children. However, when the pain is severe and colicky or the child appears unusually ill, it can be difficult to distinguish from a surgical emergency on clinical grounds alone. Imaging is used to rule out the more serious diagnosis of intussusception in these atypical or severe cases.

Pathologic Lead Point
While most pediatric intussusceptions are idiopathic, a small percentage are caused by a pathologic lead point, such as a Meckel’s diverticulum, polyp, lymphoma, or duplication cyst. While ultrasound’s primary role is to diagnose the intussusception itself, it can sometimes identify the underlying lead point, which has important implications for management and recurrence risk.

Why Is Abdominal Ultrasound the Recommended Study for Suspected Intussusception?

The ACR designates US abdomen as ‘Usually appropriate’ for the initial evaluation of suspected pediatric intussusception because it is a highly accurate, safe, and efficient diagnostic tool for this specific clinical question.

Ultrasound has excellent sensitivity and specificity for detecting intussusception. The sonographer can directly visualize the telescoped bowel, which appears as a “target” or “doughnut” sign in a transverse view and a “pseudokidney” or “sandwich” sign in a longitudinal view. The modality also allows for dynamic assessment, and color Doppler can be used to evaluate for blood flow within the bowel wall, providing critical information about the risk of ischemia. A key advantage of ultrasound is its complete lack of ionizing radiation (Pediatric RRL: O 0 mSv), a crucial consideration in the pediatric population.

Alternative imaging studies are rated lower for this initial workup for clear reasons:

  • Radiography abdomen and pelvis is rated ‘May be appropriate’. Abdominal X-rays are not sensitive or specific enough to definitively diagnose or exclude intussusception. They may show indirect signs like a soft-tissue mass, the absence of gas in the right lower quadrant (Dance’s sign), or signs of a distal bowel obstruction. However, a normal radiograph does not rule out the diagnosis. Its use can delay the definitive diagnosis provided by ultrasound and exposes the child to radiation (Pediatric RRL: ☢☢☢ 0.3-3 mSv).
  • CT abdomen and pelvis with IV contrast is rated ‘Usually not appropriate’ for the initial workup. CT provides excellent anatomical detail and can diagnose intussusception, but it involves a significant radiation dose (Pediatric RRL: ☢☢☢☢ 3-10 mSv) and often requires sedation in young children. It is an unnecessary escalation when ultrasound is readily available and highly effective. CT is typically reserved for complex cases where the ultrasound is equivocal or there is suspicion of perforation or another diagnosis not well-visualized by sonography.

When ordering the study, it is helpful to clearly state the clinical indication, such as “Rule out intussusception.” This ensures the sonographer and radiologist perform a targeted examination, systematically evaluating the entire colon from the cecum to the rectum to locate or exclude the presence of an intussusceptum.

What’s Next After US abdomen? Downstream Workflow

The results of the abdominal ultrasound will directly guide the next steps in management. The clinical workflow diverges based on whether the findings are positive, negative, or indeterminate.

If the ultrasound is positive for intussusception:
This is a surgical emergency. The immediate next step is a consultation with pediatric surgery and/or pediatric radiology. The standard treatment is a non-operative therapeutic enema (using air or a liquid contrast agent) performed under fluoroscopic or sometimes sonographic guidance. The enema attempts to hydrostatically or pneumatically reduce the intussusception. The patient should be made NPO, and IV access should be established for fluid resuscitation in preparation for the procedure. If the enema is unsuccessful or if there are signs of perforation or peritonitis, the child will require surgical reduction.

If the ultrasound is negative for intussusception:
A negative, high-quality ultrasound effectively rules out the diagnosis. The clinical team should then reconsider the differential diagnosis. If an alternative diagnosis like mesenteric adenitis or gastroenteritis is identified or suspected, management becomes supportive. If the child’s pain persists or worsens despite a negative ultrasound, further evaluation for other causes of abdominal pain (such as appendicitis or malrotation with midgut volvulus) may be necessary, potentially involving further imaging or surgical consultation depending on the clinical picture.

If the ultrasound is indeterminate or equivocal:
In rare cases, the ultrasound may be technically limited or the findings unclear. The next step depends on the degree of clinical suspicion. If suspicion remains high, a repeat ultrasound after a short interval or proceeding directly to a diagnostic/therapeutic contrast enema may be warranted. In very complex or atypical cases, a CT scan might be considered to clarify the anatomy and rule out other pathologies, though this is uncommon.

Pitfalls to Avoid (and When to Get Help)

Navigating the workup for suspected intussusception requires vigilance to avoid common diagnostic and management errors.

  • Delaying the Ultrasound: Intussusception can lead to bowel ischemia. Time is critical. Do not delay the definitive ultrasound for non-diagnostic studies like abdominal radiographs if clinical suspicion is high.
  • Over-relying on the “Classic Triad”: Waiting for the full triad of colicky pain, palpable mass, and currant jelly stool will miss many cases. Maintain a high index of suspicion based on the pattern of pain and associated lethargy alone.
  • Misinterpreting a Normal Period: Children with intussusception can appear completely well and pain-free between episodes. Do not be falsely reassured by a child who looks well upon arrival; the intermittent nature of the pain is a key feature.
  • Ignoring Sonographer Feedback: An experienced pediatric sonographer can provide valuable real-time information. If they are struggling with a technically difficult scan or have a high suspicion despite unclear images, take their concerns seriously.

If the patient shows signs of shock, peritonitis (abdominal rigidity, rebound tenderness), or sepsis, escalate immediately to a pediatric surgical service and an anesthesiologist, as the child may be too unstable for an enema and require immediate surgical intervention.

Related ACR Topics and Tools

This article covers a single, focused clinical scenario. For a comprehensive overview of imaging for all pediatric abdominal pain presentations, from appendicitis to constipation, please see our parent guide. For additional tools to help with study selection, protocoling, and patient communication, see the resources below.

Frequently Asked Questions

Is an abdominal X-ray ever the right first step for suspected intussusception?

According to the ACR, an abdominal radiograph is rated ‘May be appropriate’ but is not the recommended initial study if your suspicion for intussusception is high. While it can show signs of bowel obstruction or perforation, it cannot reliably rule out intussusception. A normal X-ray does not exclude the diagnosis, and ordering one should not delay the definitive abdominal ultrasound.

What if the ultrasound is negative but my clinical suspicion for intussusception remains very high?

This is an important clinical dilemma. First, ensure the ultrasound was a high-quality, complete study. Spontaneous reduction of an intussusception can occur. If the child’s symptoms persist or recur, a repeat ultrasound is a reasonable next step. In rare, highly concerning cases, a diagnostic contrast enema may be considered after discussion with a pediatric radiologist and surgeon.

Can ultrasound be used to perform the reduction, instead of fluoroscopy?

Yes, sonographically-guided enema reduction is a valid technique performed at some centers. It avoids the use of ionizing radiation. The choice between fluoroscopic and sonographic guidance often depends on local institutional preference, resources, and radiologist expertise. Both methods have high success rates when performed by experienced teams.

Does the presence of ‘currant jelly’ stool automatically mean the child needs surgery?

No. Currant jelly stool is a classic sign of intussusception resulting from sloughed mucosa, blood, and mucus, and it indicates significant vascular compromise. While it is an ominous sign that increases urgency, it is not an absolute contraindication to attempting a non-operative therapeutic enema. However, if the child also has signs of peritonitis or perforation, surgical intervention is required.

What is the role of CT or MRI for suspected intussusception?

For the initial diagnosis of uncomplicated ileocolic intussusception in a child, CT and MRI are rated ‘Usually not appropriate’ by the ACR. They are not used as first-line tools due to the high accuracy of ultrasound and the radiation (for CT) or sedation/time (for MRI) involved. CT may be used in rare, complex situations, such as when the ultrasound is equivocal, there is a concern for perforation, or to evaluate for a suspected pathologic lead point in an atypical patient (e.g., an older child).

Reviewed by Pouyan Golshani, MD, Interventional Radiologist — May 30, 2026