Bidirectional Endoscopic Evaluation and Management of Iron‑Deficiency Anemia

Diagnostic Evaluation

Bidirectional endoscopy (upper endoscopy with small‑bowel biopsies plus colonoscopy) is required for all patients with iron‑deficiency anemia because dual gastrointestinal pathology is present in 10–15 % of cases and serious lesions must be excluded 1.
Upper endoscopy identifies a causative lesion in 30–50 % of iron‑deficiency anemia patients 1.
Small‑bowel biopsies should be obtained during every upper endoscopy; celiac disease is found in 2–3 % of these patients 1.
Minor upper‑GI findings (e.g., mild esophagitis, erosions, aphthous ulcers, peptic ulcer) should not be accepted as the sole explanation for iron deficiency 2.
Colonoscopy must follow upper endoscopy (unless carcinoma or celiac disease is already diagnosed) because 10–15 % of patients have concurrent lower‑GI pathology 2.
Colonoscopy is superior to barium enema for detecting angiodysplasia and permits tissue biopsy 1.
Bidirectional endoscopy can be performed in a single session to improve efficiency 1.

Women older than 50 years with iron‑deficiency anemia require full gastrointestinal investigation regardless of menstrual bleeding 2.

Oral iron supplementation is recommended for all patients to correct anemia and replenish iron stores 2.
Iron therapy should be continued for 3 months after hemoglobin normalization to fully restore body stores 2.

Small‑bowel evaluation is indicated when any of the following are present:
2
Enteroscopy can detect and treat small‑bowel angiodysplasia in transfusion‑dependent patients 2.
Small‑bowel radiologic studies are rarely useful except when Crohn’s disease is suspected 2.

Hemoglobin and mean corpuscular volume (MCV) should be monitored every 3 months for the first year and then annually 2.
If hemoglobin and MCV cannot be maintained despite iron supplementation, further diagnostic investigation is warranted 2.

Do not cease gastrointestinal investigation after identifying minor upper‑GI lesions; a complete lower‑GI evaluation is required 2.
Faecal occult blood testing is not recommended for diagnosing iron‑deficiency anemia because it is insensitive and non‑specific 2.

The European Society of Gastrointestinal Endoscopy recommends performing bidirectional endoscopy (gastroscopy and colonoscopy) as first-line investigation in adults with newly diagnosed iron deficiency anemia, along with urinalysis and coeliac disease screening 3
A detailed history should be taken, focusing on NSAID or aspirin use, dietary iron intake, family history of bleeding disorders or telangiectasia, and symptoms of GI bleeding, as these factors can contribute to iron deficiency anemia 4, 5
Urinalysis or urine microscopy should be performed to exclude urinary tract bleeding as a rare cause of iron deficiency anemia 3, 6

Coeliac disease screening should be performed serologically (tissue transglutaminase antibody with IgA level), as coeliac disease is found in 3-5% of iron deficiency anemia cases and represents a non-bleeding cause of iron deficiency 3, 6
Gastroscopy is expected to reveal a cause in 30-50% of patients, and small bowel biopsies should be obtained during gastroscopy even if the mucosa appears normal, as 2-3% of iron deficiency anemia patients have coeliac disease 4, 5, 7, 6
Colonoscopy should be performed even if upper endoscopy reveals a lesion, as dual pathology occurs in 10-15% of patients, and colonoscopy is superior to barium enema for demonstrating angiodysplasia and allowing biopsy 4, 7, 8

If the initial workup is negative, further investigation of the small bowel and renal tract is indicated if there is an inadequate response to iron replacement therapy, recurrent iron deficiency anemia, or transfusion-dependent anemia 3, 6
Capsule endoscopy is the preferred test for examining the small bowel, as it is highly sensitive for mucosal lesions, and CT or MRI enterography may be considered if capsule endoscopy is not suitable 3, 6

Iron replacement therapy should not be deferred while awaiting investigations, unless colonoscopy is imminent, and investigation should not be stopped after finding minor upper GI lesions, as full evaluation is still required 3, 6, 4, 7
Dietary deficiency should not be assumed as the sole cause, and symptoms should not be relied upon to guide investigation, as they rarely correlate with findings 4, 5