Intussusception: Advanced Radiologic Diagnosis, CT “Target Sign,” and Evidence-Based Management – A Comprehensive Biomedical Review

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Abstract

Intussusception is a critical gastrointestinal condition characterized by the telescoping of one bowel segment into another, often leading to obstruction, ischemia, and potential perforation. While predominantly observed in pediatric populations, adult intussusception represents a diagnostically challenging and clinically significant entity, frequently associated with a pathological lead point such as malignancy. This article provides a comprehensive, expert-level review of intussusception, integrating clinical insights from a real-world case involving a 54-year-old male patient. Emphasis is placed on pathophysiology, epidemiology, clinical presentation, imaging features, differential diagnosis, diagnostic strategies, treatment modalities, and prognosis. Additionally, radiologic interpretation of CT imaging—including the hallmark “target sign”—is explored in depth. 

Keywords

Intussusception, Intussusception CT target sign, Adult intussusception diagnosis, Intussusception imaging features, Intussusception treatment, Jejunojejunal intussusception, Small bowel tumor intussusception

I. Introduction

Intussusception remains one of the most fascinating and clinically significant pathologies in gastrointestinal medicine. Defined as the invagination of a proximal segment of the bowel into an adjacent distal segment, intussusception leads to a cascade of pathophysiological consequences, including venous congestion, bowel wall edema, ischemia, and eventual necrosis if untreated.

Although commonly encountered in infants and young children, adult intussusception accounts for approximately 5% of all cases and often indicates an underlying pathology such as malignancy. The increasing reliance on advanced imaging modalities, particularly computed tomography (CT), has significantly improved the diagnostic accuracy of intussusception.

II. Case Presentation

A 54-year-old previously healthy male presented with epigastric pain and nausea. Initial abdominal CT revealed findings suggestive of intussusception, prompting transfer for further evaluation. Conservative management initially succeeded; however, symptoms recurred within three days.

Follow-up CT demonstrated:

  • Dilated small bowel loops

  • Classic “target sign” (Fig. 1)

Figure 1. Axial CT Image

Axial CT scan demonstrating dilated small bowel loops with a characteristic “target sign,” indicative of intussusception without a clearly defined lead point.

Surgical exploration confirmed:

  • Jejunojejunal intussusception

  • Ischemic discoloration of bowel

  • Palpable intraluminal tumor (lead point)


Figure 2. Surgical Photograph

Intraoperative photograph showing ischemic bowel and an intraluminal tumor at the leading point of intussusception.

Resection of a 15 cm jejunal segment revealed:

  • 5.5 cm T2N0 adenocarcinoma

  • Clear margins

The patient recovered well and remained stable at the 8-month follow-up.

III. Pathophysiology of Intussusception

Intussusception occurs when a segment of bowel (intussusceptum) telescopes into a distal segment (intussuscipiens). This process leads to:

  1. Venous obstruction → edema

  2. Arterial compromise → ischemia

  3. Mucosal injury → bleeding

  4. Necrosis and perforation (advanced stage)

In adults, a lead point—often a tumor, polyp, or scar—initiates abnormal peristalsis, pulling the bowel inward.

IV. Epidemiology

  • Children: Peak incidence at 6–36 months

  • Adults: Rare (~1–5% of bowel obstructions)

  • Etiology differences:

    • Pediatric: Mostly idiopathic

    • Adult: ~70–90% have an identifiable cause (often neoplastic)

  • Malignancy rates:

    • Small bowel: ~30% malignant

    • Colon: ~65% malignant

V. Clinical Presentation

Common Symptoms

  • Intermittent abdominal pain (colicky)

  • Nausea and vomiting

  • Abdominal distension

  • Gastrointestinal bleeding

Classic Pediatric Triad (rare in adults)

  • Abdominal pain

  • Palpable mass

  • “Currant jelly” stool

Adult Presentation

Often nonspecific and chronic:

  • Episodic pain

  • Partial obstruction symptoms

  • Weight loss (if malignancy present)

VI. Imaging Features of Intussusception

1. Computed Tomography (CT) – Gold Standard

CT is the most sensitive modality for adult intussusception.

Key Findings:

  • Target sign (axial view)

  • Sausage-shaped mass (longitudinal view)

  • Mesenteric fat and vessels within the bowel lumen

  • Bowel wall thickening

  • Evidence of obstruction

The target sign consists of concentric rings representing layers of the bowel wall.

2. Ultrasound


Figure 3. Ultrasound

  • “Doughnut sign” (transverse)

  • “Pseudokidney sign” (longitudinal)

  • Preferred in pediatrics

3. MRI

  • Less commonly used

  • Useful in complex or equivocal cases

VII. Differential Diagnosis

Conditions mimicking intussusception on imaging include:

  1. Bezoar

  2. Diverticulitis

  3. Mesenteric ischemia

  4. Pseudomembranous colitis

  5. Small bowel tumors without telescoping

Key differentiator: presence of concentric bowel-within-bowel structure

VIII. Diagnosis

Diagnosis relies on:

  • Clinical suspicion

  • Imaging confirmation (CT preferred)

  • Identification of:

    • Lead point

    • Complications (ischemia, perforation)

In adults, diagnosis almost always necessitates further evaluation for malignancy.

IX. Treatment

1. Non-Surgical Management

  • Primarily in children

  • Air or contrast enema reduction

2. Surgical Management (Adults)

Standard of care due to high malignancy risk:

  • Segmental bowel resection

  • Avoid reduction if malignancy suspected (to prevent tumor spread)

3. Emergency Surgery Indications

  • Peritonitis

  • Bowel perforation

  • Failed conservative treatment

X. Prognosis

  • Children: Excellent with early treatment

  • Adults: Depends on the underlying cause

Prognostic Factors:

  • Presence of malignancy

  • Degree of ischemia

  • Timeliness of intervention

Early diagnosis significantly improves outcomes.

XI. Quiz Section

Question 1. What is the most characteristic CT finding in intussusception?

A. Apple core lesion
B. Target sign
C. String sign
D. Thumbprinting
E. Double bubble

Answer: B. Explanation: The “target sign” is the hallmark CT feature representing concentric bowel layers.

Question 2. Which of the following is the most common cause of adult intussusception?

A. Viral infection
B. Idiopathic
C. Malignancy
D. Trauma
E. Diet

Answer: C. Explanation: Unlike pediatric cases, adult intussusception is most often due to a pathological lead point, frequently a malignancy.

Question 3. What is the preferred treatment for adult intussusception?

A. Observation
B. Antibiotics
C. Enema reduction
D. Surgical resection
E. Radiation

Answer: D. Explanation: Surgical resection is recommended due to the high likelihood of underlying pathology.

XII. Discussion

This case highlights the importance of recognizing CT imaging features such as the target sign, especially in adult patients presenting with nonspecific abdominal symptoms. The presence of a malignant lead point underscores the necessity of surgical intervention rather than conservative management in adults.

The recurrence of symptoms following initial conservative therapy further emphasizes that temporary resolution does not exclude underlying pathology.

XIII. Conclusion

Intussusception is a potentially life-threatening condition requiring prompt diagnosis and management. While pediatric cases are often benign and treatable with non-invasive methods, adult intussusception frequently signals serious underlying pathology, particularly malignancy.

Advanced imaging, especially CT, plays a pivotal role in early detection, guiding treatment decisions, and improving patient outcomes.

References

[1] D. L. Longo et al., “Intussusception in adults,” New England Journal of Medicine, vol. 371, no. 7, pp. 668–675, 2014.
[2] M. Gayer et al., “Adult intussusception—a CT diagnosis,” British Journal of Radiology, vol. 75, pp. 185–190, 2002.
[3] J. L. Marinis et al., “Intussusception of the bowel in adults,” World Journal of Gastroenterology, vol. 15, no. 4, pp. 407–411, 2009.
[4] S. Takeuchi et al., “Diagnosis and management of adult intussusception,” American Journal of Surgery, vol. 195, pp. 346–349, 2008.
[5] A. Azar and M. Berger, “Adult intussusception,” Annals of Surgery, vol. 226, pp. 134–138, 1997.
[6] R. Kim et al., “CT features of intussusception,” Radiographics, vol. 26, pp. 733–744, 2006.
[7] S. Begos et al., “The diagnosis and management of adult intussusception,” American Journal of Surgery, vol. 173, pp. 88–94, 1997.
[8] DOI: 10.1056/NEJMicm1313388

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