What can a capsule endoscopy (CE) show that a colonoscopy and esophagogastroduodenoscopy (EGD) would miss?

What Capsule Endoscopy Can Detect That Colonoscopy and EGD Miss

Capsule endoscopy primarily visualizes the entire small intestine (jejunum and ileum), which lies beyond the reach of both standard upper endoscopy (EGD) and colonoscopy, making it the definitive test for detecting small bowel pathology that these conventional procedures cannot access. 1

Primary Anatomic Advantage: The Small Bowel

The fundamental advantage of capsule endoscopy is complete visualization of the small intestine, which represents approximately 75% of the gastrointestinal tract length but remains inaccessible to conventional endoscopy. 1 Standard EGD typically reaches only to the proximal duodenum (C-loop), while colonoscopy reaches the terminal ileum at best, leaving the vast majority of the small bowel unexamined. 1

Specific Lesions Detected in the Small Bowel

Vascular Lesions (Most Common)

• Angiectasias/arteriovenous malformations account for up to 80% of obscure bleeding cases and are the most frequently identified pathology on capsule endoscopy. 1, 2
• These vascular lesions are particularly common in patients older than 40 years, comprising up to 40% of all small bowel bleeding causes. 1

Small Bowel Tumors

• Small bowel neoplasms are the most common cause of obscure bleeding in patients younger than 50 years, making aggressive investigation with capsule endoscopy particularly important in this age group. 1, 2
• Capsule endoscopy allows early diagnosis of small bowel tumors that would otherwise remain undetected until advanced stages. 1

Inflammatory Conditions

• Crohn's disease involving the jejunum and mid-small bowel, beyond the reach of ileocolonoscopy. 1
• NSAID-induced small bowel ulcerations and erosions, which are common but invisible to conventional endoscopy. 1
• Segmental celiac disease affecting the small intestine. 3

Other Small Bowel Pathology

• Dieulafoy's lesions in the small bowel (more common in younger patients). 1
• Meckel's diverticulum with bleeding. 3
• Small bowel strictures and areas of active inflammation in Crohn's disease patients after surgery. 1

Lesions Missed by Conventional Endoscopy (Within Their Reach)

Importantly, capsule endoscopy can also identify lesions that were missed during previous EGD or colonoscopy, even though these areas were technically within reach of conventional scopes. 1, 4

Upper GI Lesions Missed by EGD

• Gastric antral vascular ectasia (GAVE) that was overlooked. 1, 4
• Lesions in blind spots: high lesser curve, under the incisura angularis, and posterior wall of the duodenal bulb. 1
• Inflamed pyloric canal polyps. 4
• Obscure angiectasias in the stomach. 1

Lower GI Lesions Missed by Colonoscopy

• Cecal carcinomas with active bleeding that were missed on previous colonoscopies. 4
• Cecal angiodysplasias causing bleeding. 4
• Colonic neoplasms and angioectasias that were not visualized during initial examination. 1

The 2017 guidelines specifically recommend reviewing the entire capsule endoscopy examination because it may provide clues to bleeding from stomach and colon that were overlooked by conventional endoscopy. 1

Clinical Context for Use

When to Order Capsule Endoscopy

• For overt obscure bleeding (excluding hematemesis) with negative high-quality EGD and colonoscopy, capsule endoscopy should be performed as soon as possible as the next diagnostic step. 1
• For occult bleeding with iron deficiency anemia and negative conventional workup, comprehensive evaluation including capsule endoscopy is recommended. 1, 2
• The diagnostic yield is highest (64.3%) in patients with ongoing overt bleeding compared to occult bleeding (31.3%). 3

Important Caveats

• Capsule endoscopy cannot localize lesions precisely or provide therapeutic intervention, unlike conventional endoscopy. 5
• Capsule retention is the main complication, occurring particularly in patients with Crohn's disease, strictures, or prior surgery. 1, 3
• Lesions can be missed due to poor bowel preparation, rapid or delayed transit, or camera orientation away from pathology. 5
• Distal ileum visualization is often suboptimal (good visualization in only 38% of cases), which may limit detection of terminal ileal pathology. 6