What is the appropriate management for a patient with severe anemia (hemoglobin 5 g/dL), no prior medical history, and a negative abdominal/pelvic CT for gastrointestinal bleeding?

Management of Severe Anemia (Hemoglobin 5 g/dL) with Negative CT Abdomen/Pelvis

This patient requires immediate blood transfusion to maintain hemoglobin above 7 g/dL, followed by urgent bidirectional endoscopy (both upper endoscopy and colonoscopy) to identify the bleeding source, as severe iron deficiency anemia of this magnitude mandates full gastrointestinal investigation regardless of negative CT imaging. 1, 2

Immediate Resuscitation

• Transfuse packed red blood cells immediately to maintain hemoglobin above 7 g/dL (or 9 g/dL if the patient has massive bleeding or significant cardiovascular comorbidities). 1
• Hemoglobin of 5 g/dL represents life-threatening anemia requiring urgent correction before proceeding with diagnostic evaluation. 1

Diagnostic Algorithm

Step 1: Upper Endoscopy (EGD) First

• Perform esophagogastroduodenoscopy (EGD) as the initial diagnostic procedure, as it provides both diagnostic and therapeutic capabilities. 1
• This is critical because 10-15% of patients presenting with severe anemia or even hematochezia actually have an upper GI source identified on upper endoscopy. 1, 2
• During EGD, obtain small bowel biopsies to rule out celiac disease, as 2-3% of patients with iron deficiency anemia have celiac disease as the underlying cause. 2, 3
• Expected diagnostic yield of upper endoscopy is 30-50% for occult bleeding. 2

Step 2: Colonoscopy Must Follow

• Colonoscopy is mandatory even if upper endoscopy identifies a potential source (unless carcinoma or celiac disease is found), because dual pathology occurs in 10-15% of patients. 2, 3
• Colonoscopy has a diagnostic accuracy of 72-86% in patients with gastrointestinal bleeding. 4, 3
• Never assume minor findings explain the severity of anemia without completing both upper and lower GI evaluation. 2, 3

Step 3: If Both Endoscopies Are Negative

• Capsule endoscopy is the next appropriate step for evaluation of obscure bleeding, as the small bowel is the likely source when both EGD and colonoscopy are unrevealing. 3
• Angiectasia accounts for up to 80% of obscure bleeding cases from the small bowel. 3
• CT enterography (CTE) with IV contrast or capsule endoscopy are equivalent first-line options for hemodynamically stable patients with obscure recurrent bleeding after negative upper and lower endoscopy. 4

Critical Pitfalls to Avoid

• Do not attribute the anemia solely to the negative CT scan - CT abdomen/pelvis has limited sensitivity for mucosal lesions, small vascular malformations, and non-actively bleeding sources. 5
• Any degree of anemia warrants full investigation - there is no evidence that the severity of anemia correlates with the importance of underlying disease. 2
• Never stop at finding incidental findings (such as diverticula or hemorrhoids) without endoscopic confirmation that they are actively bleeding. 3
• Do not assume dietary deficiency even with a suggestive history - full GI investigation is required regardless. 2

Additional Diagnostic Considerations

• Confirm true iron deficiency with serum ferritin <12 μg/dL, though ferritin may be falsely elevated with concurrent inflammation, malignancy, or hepatic disease. 2
• Test for H. pylori during upper endoscopy, as treatment improves hemoglobin levels when present. 3
• Consider that microcytosis may be absent in combined deficiency states (e.g., with folate deficiency), recognizable by elevated red cell distribution width. 2

Timing of Procedures

• For hemodynamically stable patients without active bleeding, early elective endoscopy ideally should be performed the morning after admission following appropriate resuscitation. 1
• Emergency endoscopy within 24 hours is reserved for unstable patients with active bleeding. 1