Occult bleeding refers to blood loss that is not apparent to the naked eye. It often goes unnoticed because it does not produce visible signs like bright red blood or dark, tarry stools. Detecting occult bleeding typically requires specific laboratory tests that can identify microscopic amounts of blood. Its detection is significant as it can indicate an underlying medical condition requiring investigation.
What Occult Bleeding Means
The term “occult” signifies “hidden” or “not apparent” blood loss. This hidden nature makes occult bleeding a concern because ongoing blood loss can lead to chronic anemia, where the body lacks enough healthy red blood cells. Anemia can cause various symptoms and, if left unaddressed, may strain the heart and other organs. Recognizing occult bleeding is also important because it often points to an underlying medical issue that needs to be identified and treated.
Signs That May Prompt Testing
Occult bleeding itself does not produce direct, visible signs; its presence is often inferred from the body’s response to chronic blood loss. The primary indicator that may prompt a healthcare provider to suspect occult bleeding is unexplained iron deficiency anemia. This condition develops as the body depletes its iron stores due to ongoing blood loss, which is needed to produce hemoglobin. Symptoms of iron deficiency anemia can include persistent fatigue, pale skin, shortness of breath, dizziness, and generalized weakness. These manifestations are not symptoms of the bleeding itself but rather consequences of the body’s reduced capacity to carry oxygen.
How Occult Bleeding Is Detected
Detecting occult bleeding, particularly from the gastrointestinal tract, involves several diagnostic methods. One common approach is the Fecal Occult Blood Test (FOBT), which identifies blood in stool samples. While widely used for colorectal cancer screening, its limitations include potential false positives from certain foods or medications, and false negatives from vitamin C intake.
A more specific test is the Fecal Immunochemical Test (FIT), which directly detects human hemoglobin in stool. It offers an advantage over FOBT as it is not affected by dietary restrictions and has higher specificity for lower gastrointestinal bleeding. FIT is a preferred method for colorectal cancer screening due to its improved accuracy. If these initial stool tests suggest bleeding, further investigations are warranted.
Endoscopic procedures provide direct visualization of the digestive tract. An upper endoscopy, or esophagogastroduodenoscopy (EGD), involves inserting a flexible tube with a camera through the mouth to examine the esophagus, stomach, and duodenum. A colonoscopy uses a similar scope inserted through the rectum to visualize the large intestine. Both procedures allow for the identification of bleeding sources, such as ulcers or polyps, and enable biopsies for further analysis.
For suspected bleeding in the small bowel, which is beyond the reach of standard endoscopes, capsule endoscopy may be employed. This procedure involves swallowing a small capsule containing a camera that captures images as it travels through the digestive tract, transmitting them to a recording device worn by the patient. The specific diagnostic test chosen depends on the patient’s symptoms, risk factors, and the suspected location of the bleeding.
Underlying Conditions Causing Occult Bleeding
Occult bleeding most frequently originates from the gastrointestinal tract and can be caused by various medical conditions. Colorectal polyps are a common source, which are growths on the lining of the colon or rectum. While many polyps are benign, some have the potential to become cancerous over time.
Colorectal cancer is a common cause of occult bleeding, and early detection through screening is important for improving outcomes. Peptic ulcers, which are sores that develop on the lining of the stomach (gastric ulcers) or the first part of the small intestine (duodenal ulcers), can also lead to blood loss. These ulcers often result from infection with Helicobacter pylori bacteria or prolonged use of non-steroidal anti-inflammatory drugs (NSAIDs).
Inflammatory Bowel Disease (IBD), including conditions like Crohn’s disease and ulcerative colitis, involves chronic inflammation of parts of the digestive tract, which can cause ulceration and bleeding. Diverticular disease, characterized by small, bulging pouches (diverticula) in the lining of the digestive system, particularly the colon, can also bleed, especially if they become inflamed (diverticulitis). Angiodysplasia, which refers to fragile, abnormal blood vessels in the gastrointestinal tract, is another potential source of occult bleeding. Less common causes include esophagitis or gastritis.
Why Early Detection Matters
Identifying the source of occult bleeding is important for a person’s health. Early diagnosis of serious conditions, such as colorectal cancer, improves the chances of successful treatment and a better prognosis. When detected in its early stages, before it has spread, colorectal cancer is often more manageable.
Early detection also allows for the prevention and treatment of chronic anemia, which, if left unaddressed, can lead to persistent fatigue and place undue strain on the heart. Pinpointing the cause of occult bleeding guides appropriate and timely medical intervention, whether it involves medication, dietary changes, or surgical procedures to resolve the underlying issue. Occult bleeding is considered a sign that prompts further investigation, rather than a diagnosis in itself.