In a 72‑year‑old man with persistent iron‑deficiency anemia, declining ferritin, three positive fecal immunochemical tests, and a colonoscopy 13 months ago that showed only a small benign adenoma, does he need a repeat colonoscopy and should he seek a second opinion from another gastroenterologist?

Repeat Colonoscopy and Second Opinion for Persistent Iron Deficiency Anemia

Yes, this patient absolutely needs repeat bidirectional endoscopy (both colonoscopy and gastroscopy), and seeking a second gastroenterologist opinion is strongly warranted given the persistent anemia with declining ferritin and multiple positive fecal tests despite a recent colonoscopy. 1

Why Repeat Endoscopy is Mandatory

The British Society of Gastroenterology explicitly recommends repeat bidirectional endoscopy when there is persistent or recurrent iron deficiency anemia despite adequate iron replacement therapy, even after recent negative or minimally positive endoscopy. 1 The key clinical indicators demanding repeat investigation in this case are:

• Persistent IDA (ongoing iron deficiency despite adequate iron replacement therapy) 1
• Declining ferritin (evidence of continued blood loss) 1
• Three positive fecal immunochemical tests (strong indicator of ongoing GI bleeding) 1
• Only 13 months since last colonoscopy (within the 2-year threshold for considering prior investigations "outdated") 1

The Critical Issue: A Small Adenoma Does NOT Explain This Clinical Picture

The finding of only a small benign adenoma at the previous colonoscopy is insufficient to explain persistent iron deficiency anemia with declining ferritin and multiple positive fecal tests. 1 The British Society of Gastroenterology guidelines specifically warn that minor lesions like erosions, esophagitis, or small polyps should not be accepted as the sole cause of iron deficiency without completing full investigation. 1

Dual pathology (lesions in both upper and lower GI tracts) occurs in 10-15% of patients with iron deficiency anemia, making it essential to investigate both sites even when one lesion is found. 1, 2

When to Repeat Endoscopy

The guidelines provide clear criteria for repeat investigation 1:

• Inadequate response to iron replacement therapy (which this patient demonstrates with declining ferritin)
• Recurrent or persistent IDA (clearly present here)
• Previous investigations felt to be inadequate or outdated (a threshold of 2 years has been suggested, but this patient's ongoing symptoms justify earlier repeat) 1

Beyond Repeat Colonoscopy: Small Bowel Investigation

If repeat bidirectional endoscopy remains negative or shows only the same small adenoma, capsule endoscopy of the small bowel should be the next step. 1 The British Society of Gastroenterology strongly recommends capsule endoscopy as the preferred test for examining the small bowel in persistent IDA because it is highly sensitive for mucosal lesions. 1

Common small bowel findings in persistent IDA include 1:

• Angioectasia/vascular malformations (most common)
• Crohn's disease
• NSAID enteropathy
• Small bowel tumors (less common but critical not to miss)

Why Consider a Second Opinion

Seeking another gastroenterologist is reasonable because 1:

• The current workup appears incomplete given persistent symptoms
• The previous gastroenterologist may have prematurely attributed the anemia to a small adenoma
• A fresh perspective may identify missed lesions or suggest alternative diagnostic approaches
• Capsule endoscopy has a miss rate for small bowel tumors, and additional investigation is warranted when there is a hemoglobin drop >40 g/L or persistent bleeding 1

Additional Investigations to Consider

Beyond repeat endoscopy, the following should be evaluated 1:

• Renal tract imaging (regardless of urinalysis results, due to the association of renal cell carcinoma with IDA) 1
• Celiac disease screening if not already done (found in 3-5% of IDA cases) 1
• Review of medications (NSAIDs, anticoagulants)

Common Pitfall to Avoid

Do not accept the small adenoma as the definitive cause without completing full investigation. The combination of declining ferritin, multiple positive fecal tests, and persistent anemia despite iron therapy indicates ongoing blood loss that a small benign adenoma cannot explain. 1 This clinical scenario demands aggressive pursuit of the underlying cause to avoid missing significant pathology, including malignancy. 1