From the Guidelines
If the endoscopy is negative, ordering a CT angiogram (CTA) of the abdomen and pelvis is a reasonable next step before referring to a hematologist/oncologist, as it can help detect bleeding rates as slow as 0.3 mL/min and has a sensitivity and specificity of 85% and 92%, respectively, for the diagnosis of active gastrointestinal bleeding 1. This approach allows you to rule out active bleeding sources in the lower gastrointestinal tract that wouldn't be visible on upper endoscopy. The CTA should be performed with IV contrast to better visualize vascular structures and potential bleeding sites, and noncontrast images should also be obtained to detect intraluminal high-attenuation material that may mimic intraluminal blood on contrast-enhanced images 1. If the patient has acute symptoms like hemodynamic instability or ongoing visible bleeding, a CTA is particularly useful for rapid triage towards definitive treatment by angiography 1. Should the CTA also return negative but the patient continues to have evidence of blood loss (dropping hemoglobin, melena, hematochezia), then referral to a hematologist/oncologist would be appropriate to evaluate for bleeding disorders, bone marrow problems, or occult malignancy. This stepwise approach is efficient because it completes the anatomical investigation before moving to hematological causes, potentially avoiding unnecessary specialist referrals if a structural cause is identified on imaging. It's worth noting that the use of CT abdomen and pelvis with IV contrast for gastrointestinal bleeding evaluation is not well supported by literature, and its primary use is for the evaluation of GI masses rather than the demonstration of bleeding 1. However, the latest guidelines and evidence support the use of CTA for the diagnosis of gastrointestinal bleeding, making it a preferred choice over CT abdomen and pelvis with IV contrast in this context 1.
From the Research
Diagnostic Approach for Unexplained Anemia with Iron Deficiency
- If endoscopy (esophagogastroduodenoscopy) returns negative, the next steps should be guided by the presence of symptoms and risk factors for malignant or inflammatory small bowel disease 2.
- A CT scan of the abdomen and pelvis may be considered to look for any bleeding, especially if there are red flags indicating malignant or inflammatory small bowel disease, such as involuntary weight loss, abdominal pain, or increased CRP 2, 3.
- However, small intestine investigation (capsule endoscopy, CT, or MRI enterography) is not recommended routinely after negative bidirectional endoscopy, unless there are specific indications 2.
- Referral to a hematologist (heme)/oncologist may be considered if there is a high suspicion of malignant disease, especially if the patient has unexplained anemia with iron deficiency and negative endoscopy results 2, 4.
Role of Imaging and Endoscopy
- Cross-sectional imaging such as computed tomography (CT) should be done to evaluate for small-bowel bleeding, followed by the latest enteroscopy, videocapsule endoscopy, and deep enteroscopy according to the severity of hemorrhage and patient conditions 3.
- Video capsule endoscopy (VCE) and device-assisted enteroscopy (DAE) are useful tools for evaluating suspected small bowel bleeding (SSBB) and iron deficiency anemia (IDA) 4.
- Upper gastrointestinal tract (GI) endoscopy and colonoscopy are essential for evaluating patients with iron deficiency anemia (IDA) due to chronic gastrointestinal bleeding 5.
Management of Iron Deficiency Anemia
- Iron replacement therapy should be initiated, along with the treatment of the underlying condition causing gastrointestinal hemorrhage 6.
- Options for iron replacement include oral and intravenous (IV) iron supplementation, with IV iron supplementation usually considered in patients not responding to or not complying with oral iron supplementation or patients having low hemoglobin concentration and requiring prompt iron repletion 6.