What are the clinical findings, diagnostic approach, and management for intussusception in an adult?

Adult Intussusception: Clinical Findings, Diagnosis, and Management

Adult intussusception requires surgical resection without reduction in most cases, as approximately 50% harbor malignancy, and CT imaging is the diagnostic modality of choice with >90% accuracy. 1

Clinical Presentation

Adult intussusception presents very differently from the pediatric form and often poses diagnostic challenges due to variable symptom patterns:

Acute Presentation

• Abdominal pain is the most common symptom, occurring in 72% of patients 2
• Nausea occurs in approximately 49% of cases 2
• Vomiting is present in 36% of patients 2
• Intestinal obstruction manifests in 70.7% of cases 3
• Bloody stools occur less commonly but increase the likelihood of surgical intervention (RR 1.9) 2

Chronic/Intermittent Presentation

• Chronic symptoms are surprisingly common, occurring in 51.2% of patients, with subacute symptoms in 24.4% and acute symptoms in only 24.4% 3
• Approximately 20% of cases are completely asymptomatic and discovered incidentally on imaging 2
• The classic pediatric triad (cramping pain, bloody diarrhea, palpable mass) is rarely complete in adults 4

Physical Examination

• Palpable abdominal mass may be present, particularly in patients who will undergo surgery 2
• Signs of bowel obstruction including distension and altered bowel sounds 3

Diagnostic Approach

Primary Imaging Modality

CT abdomen and pelvis with IV contrast is the gold standard diagnostic test, achieving 90.5% accuracy for detecting intussusception 3. The ACR Appropriateness Criteria confirm CT provides >90% diagnostic accuracy for small bowel obstruction and can identify the site, cause, and complications 5.

CT Findings

• Demonstrates the characteristic "target" or "sausage-shaped" mass 3
• Identifies lead point lesions in approximately 60% of cases 2
• Distinguishes between intussusceptions with and without organic pathology 4
• Can reveal unsuspected diagnoses such as small bowel volvulus or intussusception in patients with chronic symptoms 5

Ultrasound

• 60% accurate overall for detecting intussusception 3
• Accuracy increases to 91.7% when a palpable abdominal mass is present 3
• Less useful than CT in adults due to body habitus and need for comprehensive evaluation 5

Colonoscopy

• Effective for locating lead point lesions in ileocolic, colocolonic, and sigmoidorectal intussusceptions 3
• Should be performed for colonic intussusceptions to identify the causative lesion 3

Anatomic Classification and Pathology

Location Distribution

• Enteric (small bowel): Most common, representing 44-68% of cases 3, 1
• Ileocolic: 15-34% of cases 3
• Colocolonic: 18-24% of cases 3, 1
• Sigmoidorectal: Rare, <3% 3

Underlying Pathology

A critical distinction from pediatric intussusception: 93% of adult cases have an identifiable pathologic lesion 1, and the malignancy rate is substantial:

• Enteric intussusceptions: 48% are malignant, 52% benign 1
• Colonic intussusceptions: 43% are malignant, 57% benign 1
• Overall malignancy rate: Approximately 50% across all locations 1
• Idiopathic cases (no lead point): Only 8-20% 4

Common Lead Point Lesions

• Malignant tumors (primary or metastatic) 4, 1
• Benign tumors and polyps 3, 4
• Inflammatory bowel disease 4
• Postoperative adhesions 4
• Meckel's diverticulum 4
• Iatrogenic causes (intestinal tubes, jejunostomy tubes, post-gastric surgery) 3, 4

Management

Surgical Principles

Formal bowel resection without reduction is the preferred treatment in adults, fundamentally different from pediatric management 1, 6.

Rationale for Resection Without Reduction

• High malignancy rate (approximately 50%) necessitates oncologic resection principles 4, 1
• Reduction risks seeding malignant cells if cancer is present 1
• Colonic intussusceptions especially should not be reduced before resection 6

When Reduction May Be Considered

• Benign lesions where malignancy has been definitively excluded 4
• Cases where limiting resection extent is critical to avoid short bowel syndrome 4
• Only 4 intussusceptions in 3 patients were simply reduced in one series, with 21 patients undergoing resection after primary reduction 3

Surgical Outcomes

• No mortality reported in modern series with appropriate surgical management 3
• Recurrence is rare: Only 1 patient with multiple small bowel adenomas recurred at 5 months in one series 3
• Patients presenting to the ED are more likely to undergo surgical intervention (RR 1.8) 2

Predictors of Surgical Intervention

Patients with the following are more likely to require surgery:

• Abdominal pain (RR 2.2) 2
• Nausea (RR 1.7) 2
• Vomiting (RR 1.4) 2
• Bloody stool (RR 1.9) 2
• Ileocolonic location 2
• Mass as lead point 2

Critical Pitfalls to Avoid

• Do not attempt reduction before resection in suspected malignancy, particularly in colonic cases 1, 6
• Do not dismiss chronic, intermittent symptoms as functional—over 50% of adult intussusception presents with chronic symptoms 3
• Do not rely on the pediatric triad—it is rarely complete in adults 4
• Avoid intestinal intubation as it can cause iatrogenic intussusception 3
• Do not assume benignity—93% have pathologic lesions and 50% are malignant 1