Endoscopy for Small Bowel Malignancy Diagnosis
For diagnosing small bowel malignancy, capsule endoscopy is recommended as the preferred first-line test due to its high diagnostic yield and ability to visualize the entire small bowel mucosa, especially after negative conventional endoscopy and imaging studies.
Diagnostic Approach for Small Bowel Malignancy
Initial Evaluation
- Bidirectional endoscopy (upper endoscopy and colonoscopy) should be performed first to exclude more common sources of gastrointestinal pathology before proceeding to specialized small bowel investigations 1
- Cross-sectional imaging with CT or MR enterography should be considered as complementary investigations, particularly for assessment of extraluminal extension and metastatic disease 1
Small Bowel Visualization Methods
- Capsule endoscopy (CE) is the preferred first-line test for examining the small bowel in suspected small bowel malignancy due to its high sensitivity for mucosal lesions 1
- CE has a higher diagnostic yield than conventional radiologic procedures for detecting small bowel tumors 1, 2
- Device-assisted enteroscopy (DAE) should be used when tissue sampling or therapeutic intervention is needed, guided by findings on capsule endoscopy 1, 3
Clinical Scenarios for Small Bowel Evaluation
Suspected Small Bowel Malignancy
- In patients with clinical features suggesting small bowel malignancy (iron deficiency anemia, weight loss, abdominal pain) and negative bidirectional endoscopy, capsule endoscopy is strongly recommended 1, 2
- Small bowel tumors are more common in relatively younger patients (median age 50) compared to other gastrointestinal malignancies 2
- The diagnostic yield of capsule endoscopy for small bowel tumors ranges from 0.36% to 2.4% of all procedures performed 2, 4
Obscure Gastrointestinal Bleeding
- In patients with iron deficiency anemia or occult gastrointestinal bleeding with negative standard endoscopic evaluation, capsule endoscopy should be performed to evaluate for small bowel sources including malignancy 1, 5
- Small bowel tumors account for a small percentage of cases of recurrent iron deficiency anemia, but are an important diagnosis not to miss 1, 2
Specific High-Risk Populations
- In patients with biallelic mismatch repair deficiency (BMMRD) syndrome, annual surveillance for small bowel cancer by upper endoscopy and video capsule endoscopy is recommended beginning at age 8 1
- For patients with Crohn's disease and unexplained symptoms not clarified by ileocolonoscopy or imaging studies, capsule endoscopy is recommended to evaluate for small bowel pathology including malignancy 1
Advantages and Limitations of Diagnostic Methods
Capsule Endoscopy
- Advantages: Non-invasive, high sensitivity for mucosal lesions, ability to visualize the entire small bowel 1, 4
- Limitations: Cannot obtain biopsies, risk of retention in patients with strictures, may miss some lesions 1, 2
Device-Assisted Enteroscopy
- Advantages: Allows for tissue sampling and therapeutic interventions 1
- Limitations: More invasive, requires sedation, limited availability 1
CT/MR Enterography
- Advantages: May have higher yield for tumors with extraluminal extension, evaluates surrounding structures 1
- Limitations: Less sensitive for small or flat mucosal lesions 1
Important Considerations
Capsule Retention Risk
- Capsule retention can occur in approximately 1.4% of patients, with higher risk in those with known Crohn's disease, prior small bowel surgery, or radiation enteritis 2, 4
- Consider patency capsule or cross-sectional imaging before capsule endoscopy if obstruction is suspected 1
Follow-up After Negative Capsule Endoscopy
- After a negative capsule endoscopy of acceptable quality, further gastrointestinal investigation is only recommended if there is ongoing iron deficiency anemia after iron replacement therapy 1
- Capsule endoscopy has a miss rate for small bowel tumors, so repeat investigation may be warranted with high clinical suspicion 1, 2