Intussusception Diagnosis: A Comprehensive Guide for Clinicians

Intussusception is a medical condition characterized by the telescoping of one segment of the intestine into another, much like folding a telescope. This process typically involves the small bowel, although it can less frequently affect the large bowel. The condition manifests with a range of symptoms including abdominal pain that may come and go, vomiting, abdominal distension, and the passage of bloody stools. If left untreated, intussusception can lead to serious complications such as small bowel obstruction, peritonitis, and bowel perforation. Prompt and accurate Intussusception Diagnosis is crucial for effective management and to prevent these severe outcomes. This article provides an in-depth review of intussusception, focusing on its etiology, pathophysiology, clinical presentation, and critically, the diagnostic approaches essential for healthcare professionals. Understanding the nuances of intussusception diagnosis is paramount for timely intervention and improved patient outcomes.

Causes and Risk Factors of Intussusception

While the exact cause of intussusception often remains undetermined, particularly in children, several factors are recognized to contribute to its development. In the majority of pediatric cases, approximately 90%, the cause is idiopathic. However, several potential triggers and predisposing conditions have been identified. These include:

Infections: Viral infections, such as adenovirus and rotavirus, and bacterial infections, including Salmonella, Escherichia coli, Shigella, and Campylobacter, have been associated with an increased risk of intussusception. The infection may lead to hypertrophy of Peyer’s patches in the ileum, which can act as a lead point for telescoping.
Anatomical Factors: Certain congenital or acquired anatomical abnormalities can predispose individuals to intussusception. These include Meckel’s diverticulum, intestinal duplications, and polyps, which can serve as lead points, initiating the invagination process. Appendicitis can also be a rare predisposing factor.
Altered Motility: Changes in bowel motility, whether due to infections, medications, or other underlying conditions, can disrupt normal peristalsis and contribute to intussusception.
Hyperplasia of Peyer’s Patches: As mentioned, the lymphoid hyperplasia of Peyer’s patches, often secondary to viral infections, is a significant factor, especially in ileocolic intussusception, the most common type in children.
Cystic Fibrosis: Children with cystic fibrosis have a higher incidence of intussusception, possibly related to thickened intestinal contents and altered motility.

In adults, intussusception is less common and is frequently associated with an identifiable lead point. Common causes in adults include:

Intestinal Tumors: Benign and malignant tumors, such as adenomas, lipomas, lymphomas, and adenocarcinomas, are the most frequent lead points in adult intussusception.
Bowel Adhesions: Previous surgeries can lead to adhesions that may alter bowel anatomy and motility, predisposing to intussusception.
Endometriosis: In women, endometriosis affecting the bowel can be a rare cause of intussusception.
Inflammatory Bowel Disease: Conditions like Crohn’s disease can increase the risk of intussusception due to inflammation and structural changes in the bowel wall.

It is worth noting that an early formulation of the rotavirus vaccine (Rotashield) was linked to an increased risk of intussusception and was subsequently withdrawn from the market. However, current rotavirus vaccines have not shown a clear association with a significantly elevated risk.

Incidence and Prevalence of Intussusception

Intussusception is predominantly a condition of infancy and early childhood.

Incidence in Children: In the United States, approximately 2,000 infants in their first year of life are diagnosed with intussusception annually.
Age Distribution: The peak incidence occurs between four and nine months of age, with most cases presenting between five and 18 months. The incidence gradually declines after 18 months of age.
Sex Predilection: Intussusception is more common in boys than girls, with a male-to-female ratio of about 3:1.
Adult Intussusception: In adults, intussusception is a rare cause of bowel obstruction, accounting for only about 1% of all cases. It is frequently associated with underlying pathology, particularly neoplasms.

Mechanisms of Intussusception

The pathophysiology of intussusception involves the invagination of a proximal segment of the intestine (intussusceptum) into a distal segment (intussuscipiens). The ileocecal junction is the most common site, with the ileum telescoping into the cecum and colon (ileocolic intussusception).

Peristalsis and Lead Points: Normal peristaltic activity of the bowel propels the proximal segment into the distal segment. In cases with a lead point (anatomical abnormality or lesion), this point is dragged into the distal segment, initiating the intussusception. However, in many cases, particularly in children, no distinct lead point is identified.
Vascular Compromise: As the intussusceptum telescopes into the intussuscipiens, the mesentery containing blood vessels is also drawn in and compressed. This compression can compromise the blood supply to the trapped segment of the bowel, leading to ischemia, edema, and eventually necrosis if not promptly resolved.
Mucosal Sloughing and “Red Currant Jelly” Stool: Ischemia of the bowel mucosa leads to its sloughing and bleeding into the bowel lumen. This mixture of sloughed mucosa, blood, and mucus is passed as “red currant jelly” stool, a classic but not always present sign of intussusception. This symptom, while indicative, is observed in a minority of cases and should be considered within the broader clinical picture.

Clinical Presentation and Symptoms of Intussusception

The clinical presentation of intussusception can vary, but classic symptoms and signs aid in intussusception diagnosis.

Abdominal Pain: Typically, the initial symptom is sudden onset of colicky abdominal pain. In infants, this may manifest as sudden, loud crying, drawing the knees to the chest, and appearing inconsolable. The pain is often intermittent, corresponding to peristaltic waves attempting to overcome the obstruction. Between episodes of pain, the child may appear relatively comfortable.
Vomiting: Vomiting usually follows the onset of pain and may initially be non-bilious but can become bilious (green) as the obstruction progresses.
Bloody Stool: Passage of “red currant jelly” stool, as described earlier, is a later sign. It is important to note that this is not always present, and its absence does not rule out intussusception. Any bloody stool in a child should raise suspicion.
Lethargy: As the condition progresses, particularly if ischemia develops, the child may become lethargic and less responsive.
Abdominal Distension: Bloating and abdominal distension can occur due to bowel obstruction.

On physical examination, several signs may be present:

Sausage-Shaped Mass: Palpation of the abdomen may reveal a sausage-shaped mass, typically in the right upper or mid-abdomen. This mass represents the intussusceptum within the intussuscipiens.
Dance Sign: In some cases, a Dance sign may be noted, characterized by emptiness in the right lower quadrant where the cecum would normally be located, due to the telescoping of the ileocecum upwards and out of the iliac fossa.
Rectal Examination: A digital rectal examination may reveal blood on the glove and, in some instances, the tip of the intussusceptum may be palpable.

It’s crucial to remember that fever is not a primary symptom of uncomplicated intussusception. Fever suggests a complication such as bowel necrosis, perforation, and subsequent sepsis. In rare instances, intussusception can be associated with Henoch-Schönlein purpura, in which case patients may present with both typical Henoch-Schönlein purpura signs and severe abdominal pain due to intussusception.

Diagnostic Approaches and Imaging for Intussusception Diagnosis

Prompt and accurate intussusception diagnosis is essential to prevent complications. Clinical suspicion based on history and physical examination is the first step, followed by confirmatory imaging.

Ultrasound: Ultrasound is the preferred initial imaging modality for intussusception diagnosis in children due to its high accuracy, lack of radiation, and speed. Characteristic ultrasound findings include:
- Target Sign or Doughnut Sign: On transverse view, intussusception appears as concentric rings, resembling a target or doughnut. This is due to the alternating layers of the intussusceptum and intussuscipiens.
- Sandwich Sign or Pseudokidney Sign: On longitudinal view, the intussusception may resemble a sandwich or a pseudokidney.
The typical diameter of the target sign is around 3 cm. Color Doppler ultrasound can also assess blood flow within the intussuscepted bowel, which can be helpful in evaluating for ischemia.
Abdominal X-ray: While less sensitive and specific than ultrasound for intussusception diagnosis, an abdominal X-ray may be performed initially, especially to rule out free perforation or obstruction. X-ray findings may include signs of bowel obstruction, but it is not diagnostic for intussusception itself.
Air Enema: Air enema is not only diagnostic but also therapeutic for intussusception in children. Under fluoroscopic guidance, air is gently insufflated into the rectum. The air column can outline the intussusception, confirming the diagnosis. Furthermore, the pressure from the air enema can often reduce the intussusception, making it a treatment modality as well.
Contrast Enema (Water-soluble or Barium): Similar to air enema, contrast enemas using water-soluble contrast or barium can be both diagnostic and therapeutic. However, air enema is generally preferred due to a lower risk of perforation and peritoneal irritation if perforation occurs.
Computed Tomography (CT Scan): CT scan is typically not the first-line imaging for intussusception diagnosis in children due to radiation exposure and the need for sedation in younger children. However, CT may be used in adults or in cases where ultrasound is inconclusive, or to evaluate for underlying lead points, particularly in adults. CT findings are similar to ultrasound, showing the target sign and sandwich sign.

Management and Treatment Strategies for Intussusception

Intussusception requires prompt management to prevent bowel ischemia and necrosis. The primary treatment modalities are non-surgical reduction and surgical intervention.

Non-Surgical Reduction (Enema Reduction): In children, non-surgical reduction using air enema, or less commonly, water-soluble contrast or barium enema, is the first-line treatment.
- Procedure: The enema is performed under fluoroscopic guidance. Air or contrast is gently introduced into the colon, and the pressure exerted helps to push the intussusceptum out of the intussuscipiens, reducing the intussusception.
- Success Rate: Non-surgical reduction is successful in over 80% of cases.
- Recurrence: Recurrence of intussusception can occur in up to 10% of cases within 24 hours, and patients need to be monitored post-reduction.
Surgical Reduction: Surgical intervention is indicated in cases where non-surgical reduction is unsuccessful, if there are signs of peritonitis, perforation, or if a lead point requiring surgical removal is suspected (particularly in adults).
- Open Surgical Reduction: Involves laparotomy, where the surgeon manually reduces the intussusception by gently squeezing and manipulating the bowel segments. If reduction is not possible or if bowel necrosis is present, surgical resection of the affected bowel segment with anastomosis may be necessary.
- Laparoscopic Reduction: Laparoscopy can be used in some cases to reduce intussusception. Forceps are used to gently pull apart the telescoped segments. Laparoscopy may also be used for bowel resection if needed.
Post-Reduction Management: After successful reduction, patients are typically admitted for observation. Oral feeding is gradually reintroduced. It is important to monitor for recurrence, bowel perforation, or other complications. While antibiotics are not routinely indicated after successful enema reduction, they may be considered in cases with suspected bowel compromise or surgical intervention.
Adult Intussusception Management: In adults, due to the higher likelihood of an underlying pathological lead point, surgical resection is frequently required. Non-surgical reduction is generally not attempted in adults unless there are specific circumstances and a low suspicion of malignancy.

Differential Diagnosis of Intussusception

Several conditions can mimic intussusception, and it is important to consider these in the differential intussusception diagnosis:

Appendicitis: Can present with abdominal pain, but pain in appendicitis is typically localized to the right lower quadrant and progressive.
Abdominal Hernias: Incarcerated or strangulated hernias can cause abdominal pain and vomiting.
Blunt Abdominal Trauma: Can cause abdominal pain and may need to be considered in the context of trauma history.
Colic: Infantile colic presents with crying and irritability but lacks the specific signs of intussusception like bloody stool or sausage-shaped mass.
Cyclic Vomiting Syndrome: Characterized by recurrent episodes of vomiting, but abdominal pain is usually less prominent, and other intussusception signs are absent.
Gastroenteritis: Acute gastroenteritis can cause vomiting, abdominal pain, and bloody stool, but diarrhea is usually the predominant symptom, and pain is typically less colicky and more diffuse.
Gastric Volvulus: Presents with severe abdominal pain and vomiting, but typically in older children or adults and with different imaging findings.
Internal Hernia: Can cause bowel obstruction and abdominal pain.
Testicular Torsion: In males, testicular torsion can present with abdominal pain radiating to the groin, but physical examination will reveal testicular tenderness.
Rectal Prolapse: Can present with rectal bleeding, but physical examination reveals prolapsed rectal mucosa, which is different from the findings in intussusception.

Prognosis and Outcomes of Intussusception

The prognosis for intussusception is generally excellent if diagnosed and treated promptly.

Timely Treatment: With early intussusception diagnosis and treatment, particularly non-surgical reduction in children, the outcomes are very favorable.
Untreated Intussusception: If left untreated, intussusception can lead to bowel ischemia, necrosis, perforation, sepsis, and can be life-threatening within 2-5 days. In developing countries where access to timely medical care may be limited, mortality rates are significantly higher.
Factors Affecting Prognosis: The duration of intussusception before treatment is a critical factor. Prolonged intussusception increases the risk of bowel ischemia and necrosis, potentially requiring surgical resection and impacting prognosis.
Recurrence: While recurrence is possible after non-surgical reduction (up to 10%), subsequent episodes are usually managed successfully with repeat reduction or surgery if needed.

Complications of Intussusception

Potential complications of intussusception include:

Bowel Ischemia and Necrosis: Due to vascular compromise, the trapped bowel segment can become ischemic and necrotic, potentially leading to perforation.
Perforation: Bowel perforation can result in peritonitis and sepsis, requiring emergency surgery.
Bowel Obstruction: Intussusception itself causes bowel obstruction, which, if prolonged, can lead to dehydration, electrolyte imbalances, and further complications.
Short Bowel Syndrome: Rarely, extensive bowel resection due to necrosis may lead to short bowel syndrome, particularly in infants.
Postoperative Intussusception (POI): Although rare, intussusception can occur as a complication after abdominal surgeries.

Pearls and Key Considerations in Intussusception Management

Early Diagnosis is Key: Prompt recognition of intussusception symptoms and timely intussusception diagnosis are crucial to minimize complications and improve outcomes.
Ultrasound First: Ultrasound is the preferred initial diagnostic imaging modality in children due to its accuracy and safety.
Air Enema for Reduction: Air enema is the preferred non-surgical reduction method in children, offering both diagnostic and therapeutic benefits.
Adult Intussusception Requires High Suspicion for Lead Point: In adults, intussusception should prompt investigation for underlying lead points, often necessitating surgical management.
Interprofessional Approach: Management of intussusception requires a coordinated interprofessional team approach involving radiologists, pediatricians, emergency physicians, and pediatric surgeons.

Interprofessional Team Management for Enhanced Healthcare Outcomes

Effective management of intussusception requires a collaborative approach from an interprofessional healthcare team. This team typically includes:

Radiologist: Plays a crucial role in intussusception diagnosis through ultrasound, fluoroscopy during enema reduction, and CT scans when indicated. The radiologist’s expertise in image interpretation is vital for accurate diagnosis and guiding treatment.
Pediatrician/Emergency Department Physician: Is often the first point of contact, responsible for recognizing the clinical signs and symptoms of intussusception, initiating the diagnostic process, and coordinating further management.
Pediatric Surgeon: Essential for performing surgical reduction when non-surgical methods fail or when surgical resection is necessary. The surgeon also manages complications and provides post-operative care.
Nursing Staff: Provides crucial pre- and post-procedure care, monitors patients for signs of complications or recurrence, and ensures patient comfort and support.

Effective communication and coordination among these team members are essential to ensure timely intussusception diagnosis, appropriate treatment, and optimal patient outcomes. This interprofessional approach minimizes delays in care, reduces the risk of complications, and improves the overall quality of care for patients with intussusception.

Review Questions

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References

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