How Doctors Diagnose the Cause of Blood in Stools

Blood in stools can be alarming and may indicate an underlying health issue ranging from minor conditions like hemorrhoids to serious diseases such as colorectal cancer. The presence of blood can vary in appearance—bright red blood often signifies a lower gastrointestinal (GI) tract issue, while dark, tarry stools may indicate bleeding higher up in the digestive system. To determine the cause, doctors rely on a combination of medical history, physical examinations, and diagnostic tests.

Medical History and Symptom Evaluation

When a patient presents with blood in stools, doctors begin by gathering a detailed medical history. They ask about the duration and frequency of bleeding, stool color, and any associated symptoms such as abdominal pain, weight loss, or changes in bowel habits.

A history of gastrointestinal conditions, such as Crohn’s disease or ulcers, is also considered. Additionally, doctors review medication usage, as drugs like nonsteroidal anti-inflammatory drugs (NSAIDs) and blood thinners can contribute to gastrointestinal bleeding.

Physical Examination

A thorough physical examination helps doctors narrow down possible causes. This may include checking vital signs to assess the severity of blood loss and performing an abdominal examination to identify any tenderness or masses.

A digital rectal exam (DRE) is often conducted to detect abnormalities in the lower rectum, such as hemorrhoids, fissures, or palpable masses that could indicate colorectal cancer.

Diagnostic Tests

Stool Tests

Doctors may order stool tests to confirm the presence of blood and identify potential infections or inflammatory conditions. A fecal occult blood test (FOBT) or fecal immunochemical test (FIT) detects hidden (occult) blood that is not visible to the naked eye. These tests are commonly used for colorectal cancer screening as well.

Blood Tests

A complete blood count (CBC) can reveal anemia, which may suggest chronic blood loss. Other blood tests, such as liver function tests and clotting profiles, help identify conditions that may contribute to bleeding, such as liver disease or clotting disorders.

Endoscopic Examinations

Endoscopic procedures allow direct visualization of the gastrointestinal tract, helping doctors pinpoint the source of bleeding.

• Colonoscopy: This procedure involves inserting a flexible tube with a camera into the colon and rectum. It is the most effective method for detecting colorectal polyps, diverticulosis, inflammatory bowel disease (IBD), and colorectal cancer. If abnormalities are found, biopsies can be taken for further analysis.
• Sigmoidoscopy: A sigmoidoscopy examines only the lower part of the colon and rectum. It is a less invasive alternative to a full colonoscopy but may not detect issues higher up in the colon.
• Upper Endoscopy (Esophagogastroduodenoscopy or EGD): If a doctor suspects the bleeding is from the upper digestive tract, an EGD is performed. This involves inserting a flexible scope through the mouth to examine the esophagus, stomach, and duodenum for ulcers, gastritis, or tumors.

Imaging Tests

In cases where endoscopic exams are inconclusive, doctors may use imaging tests:

• CT Scan: A computed tomography (CT) scan of the abdomen can help detect tumors, abscesses, or other abnormalities that might be causing bleeding.
• Angiography: If active bleeding is suspected, an angiogram may be used to visualize blood vessels and locate the bleeding source. This is especially useful for cases of severe gastrointestinal bleeding.
• Capsule Endoscopy: For obscure gastrointestinal bleeding, capsule endoscopy allows for visualization of the small intestine, an area not easily accessible by traditional endoscopy.

Biopsy and Pathological Examination

If abnormal tissues or polyps are detected during a colonoscopy or endoscopy, doctors may perform a biopsy. A small tissue sample is taken and analyzed under a microscope to check for infections, inflammation, or cancerous cells. A biopsy is crucial for diagnosing conditions like colorectal cancer or inflammatory bowel disease.

Treatment Based on Diagnosis

Once the cause of blood in stools is identified, doctors can tailor treatment accordingly. Mild cases, such as hemorrhoids or anal fissures, may be managed with lifestyle changes and medications.

More serious conditions, like colorectal cancer, may require surgery, chemotherapy, or targeted therapies. Early diagnosis and intervention significantly improve outcomes, making it essential to seek medical attention if blood in stools occurs.

Conclusion

The presence of blood in stools should never be ignored, as it can signal both minor and serious medical conditions. Through a combination of medical history, physical exams, stool tests, blood work, and advanced diagnostic procedures like colonoscopy and imaging, doctors can accurately determine the cause. If you experience persistent or recurrent blood in stools, consulting a healthcare professional is essential for early diagnosis and appropriate treatment.