Gastrointestinal Evaluation with Bidirectional Endoscopy

Rationale for Endoscopic Investigation

The American Gastroenterological Association recommends bidirectional endoscopy for patients with iron deficiency anemia and gastrointestinal symptoms, such as diarrhea and prolonged constitutional symptoms, despite a negative initial workup 1
The presence of red flag symptoms, such as new-onset diarrhea, strengthens the indication for bidirectional endoscopy in premenopausal women with iron deficiency anemia 2

The American College of Gastroenterology recommends upper endoscopy with duodenal biopsies to evaluate for celiac disease, which can present with iron deficiency anemia, diarrhea, joint pain, and fatigue 3, 1
Bidirectional endoscopy can identify other pathology, such as erosive esophagitis, peptic ulcer disease, gastric antral vascular ectasia, and angioectasias 1

The American Gastroenterological Association recommends obtaining tissue transglutaminase IgA with total IgA before endoscopy to screen for celiac disease, although negative serology does not exclude the disease 3
Elevated inflammatory markers, such as C-reactive protein and erythrocyte sedimentation rate, support inflammatory bowel disease or other chronic inflammatory conditions 4
Urine microscopy is recommended to evaluate for microscopic hematuria as a potential source of iron loss 2

The American College of Gastroenterology advises against assuming menstrual blood loss is the sole cause of iron deficiency anemia in premenopausal women with gastrointestinal symptoms, and recommends prompt evaluation 2, 1
The American Gastroenterological Association recommends against delaying endoscopy for a trial of iron therapy in patients with diarrhea and prolonged constitutional symptoms 1

The European Society of Gastrointestinal Endoscopy recommends considering small bowel imaging, such as capsule endoscopy or MR enterography, to evaluate for small bowel Crohn's disease, angioectasias, or other small bowel pathology if bidirectional endoscopy is unrevealing 6
The American Gastroenterological Association recommends repeating inflammatory markers and celiac serology if not initially obtained 4