Diagnosing Blood in Stools

Diagnosing Blood in Stools: Tests and Examinations to Identify Underlying Conditions

The presence of blood in stools, also known as rectal bleeding, can be a concerning symptom that requires medical attention. It is essential to determine the underlying cause of blood in stools to ensure appropriate diagnosis and treatment.

In this article, we will explore the various tests and examinations used to diagnose and identify the underlying conditions associated with blood in stools.

Physical Examination and Medical History

When you visit a healthcare provider for blood in stools, they will begin by conducting a thorough physical examination and gathering your medical history. This initial assessment helps provide essential clues about your overall health and potential risk factors for various conditions.

It allows the healthcare provider to better understand your symptoms and make informed decisions regarding further diagnostic tests.

Stool Sample Analysis

One of the primary diagnostic tests for blood in stools is a stool sample analysis. This test involves providing a small sample of your stool, which is then sent to a laboratory for analysis. The laboratory technicians examine the sample for the presence of blood and can determine if it is fresh blood (bright red) or digested blood (dark and tarry).

Stool sample analysis can help identify potential causes of blood in stools, such as gastrointestinal bleeding, inflammation, infections, or certain types of cancers.


A colonoscopy is a procedure that involves the use of a long, flexible tube with a camera at the end (colonoscope) to examine the entire length of the colon and rectum. It is a valuable tool for diagnosing and identifying the source of blood in stools.

During a colonoscopy, the healthcare provider can visualize any abnormalities, such as polyps, ulcers, or tumors, and may even perform interventions such as removing polyps or obtaining tissue samples for further analysis. Colonoscopy is particularly useful in detecting conditions such as colorectal cancer or inflammatory bowel disease.

Flexible Sigmoidoscopy

Similar to a colonoscopy, a flexible sigmoidoscopy is a procedure that allows visualization of the lower part of the colon and rectum using a flexible tube with a camera (sigmoidoscope). While it does not examine the entire colon, it can help identify the source of blood in stools if the bleeding is originating from the lower part of the gastrointestinal tract.

A flexible sigmoidoscopy can detect conditions such as hemorrhoids, diverticulosis, or rectal polyps that may cause rectal bleeding.

Imaging Tests

In some cases, additional imaging tests may be necessary to further evaluate the gastrointestinal tract and identify potential causes of blood in stools. These imaging tests may include:

  • Barium Enema: This test involves the administration of a liquid contrast material (barium) into the rectum, followed by X-rays of the lower gastrointestinal tract. It can help identify abnormalities such as tumors, strictures, or abnormal growths.
  • CT Scan or MRI Scan: These imaging tests provide detailed images of the abdominal region and can help detect abnormalities such as tumors, abscesses, or inflammation in the gastrointestinal tract.
  • Capsule Endoscopy: This involves swallowing a small capsule containing a camera that takes images of the gastrointestinal tract as it passes through the digestive system. It is particularly useful in evaluating the small intestine and identifying potential sources of bleeding.

Blood Tests

Blood tests are often performed to assess your overall health status and identify potential underlying conditions associated with blood in stools. These tests may include a complete blood count (CBC) to evaluate for anemia or infection, liver function tests, coagulation profile, and specific markers that can indicate inflammation or certain diseases.


Diagnosing the underlying conditions causing blood in stools requires a comprehensive approach that includes physical examination, medical history, stool sample analysis, colonoscopy, flexible sigmoidoscopy, imaging tests, and blood tests. These diagnostic tools help healthcare providers identify the source and potential causes of blood in stools, guiding appropriate treatment plans.

It is important to remember that blood in stools should never be ignored, as it can be an indication of various conditions, ranging from minor issues to more serious diseases. Seeking timely medical attention is crucial for an accurate diagnosis and effective management. If you notice blood in your stools, make an appointment with your healthcare provider, who can assess your symptoms, perform the necessary tests, and provide appropriate guidance.

By understanding the tests and examinations used to diagnose blood in stools, you can feel more informed and prepared for your medical evaluation. Remember to communicate openly with your healthcare provider about your symptoms, medical history, and any concerns you may have. This collaborative approach will help ensure a thorough evaluation and accurate diagnosis.