Identifying the Causes of Occult Blood in Stool: A Guide

Fecal occult blood?

After testing positive for occult blood in two stool samples, I underwent an upper endoscopy, and the doctor noted inflammation.
I then had a colonoscopy, but the endoscope only reached 80 centimeters with no abnormalities observed.
How can I identify the cause of the occult blood?

Yin Yin, 30~39 year old female. Ask Date: 2000/11/15

Dr. Yang Guojun reply Internal Medicine

You can schedule a small bowel imaging study to investigate any lesions or bleeding in this segment of the intestine.
Please visit our outpatient internal medicine clinic, Room 5, with Dr.
Yang Guojun, who previously served as a research physician in the Gastroenterology and Hepatology Department at National Taiwan University Hospital.
An ultrasound scan and small bowel imaging will be arranged.

If there is upper gastrointestinal bleeding, symptoms may include vomiting blood or passing black stools (similar to tar).
If it is lower gastrointestinal bleeding, symptoms may include passing bloody stools.
The location, speed, and volume of the bleeding will affect the symptoms; the closer it is to the upper or lower exit, the greater the likelihood of vomiting or passing fresh blood.
Conversely, it may result in vomiting clots or passing black stools, or even occult blood that is not visible to the naked eye.
Chronic occult bleeding or potential sources include anal and rectal lesions such as hemorrhoids, anal fissures, anal fistulas, proctitis, trauma, rectal carcinoid tumors, solitary rectal ulcer syndrome, colonic lesions such as tumors, rectal or colon cancer, polyps, tubular adenomas, villous adenomas, familial adenomatous polyposis, Gardner syndrome, Peutz-Jeghers syndrome, and juvenile polyposis syndrome.

Reply Date: 2000/11/15

More Info

Identifying the causes of occult blood in stool can be a complex process, as it may stem from various underlying conditions. Occult blood refers to blood that is not visible to the naked eye but can be detected through specific tests. The presence of occult blood in stool can indicate several issues ranging from benign to serious conditions, and it is essential to approach this systematically.

Given your situation, where you have already undergone a gastroscopy and a colonoscopy, it is important to consider the following potential causes and next steps:
1. Gastrointestinal Inflammation: Since your gastroscopy revealed inflammation, it is crucial to determine the cause of this inflammation. Conditions such as gastritis, peptic ulcers, or esophagitis can lead to bleeding. If you have not already done so, discussing the results with a gastroenterologist may provide insights into whether further treatment or monitoring is necessary.

2. Colonic Issues: The colonoscopy you underwent only reached 80 cm, which means that the entire colon was not examined. It is possible that lesions or sources of bleeding exist beyond the area that was visualized. If you have not had a complete colonoscopy, it may be advisable to schedule one to ensure that the entire colon is examined for polyps, diverticula, or other abnormalities.

3. Small Intestinal Pathologies: Conditions affecting the small intestine, such as Crohn's disease, small bowel tumors, or vascular malformations, can also cause occult blood. If your symptoms persist and no source is identified in the upper or lower GI tract, a small bowel imaging study, such as a capsule endoscopy or a CT enterography, may be warranted.

4. Hemorrhoids or Anal Fissures: While these conditions typically cause visible blood, they can sometimes lead to occult blood as well. A thorough examination by a proctologist may help rule out these common issues.

5. Coagulation Disorders: If you have a history of easy bruising or bleeding, it may be worth investigating whether you have a bleeding disorder. Tests to evaluate your blood's clotting ability, such as PT, aPTT, and platelet counts, can help identify any underlying issues.

6. Dietary Factors: Certain foods and medications can lead to gastrointestinal bleeding. Nonsteroidal anti-inflammatory drugs (NSAIDs), anticoagulants, and even some supplements can irritate the gastrointestinal lining. Reviewing your medication and dietary habits with your doctor may provide additional clues.

7. Follow-Up Testing: If initial tests do not yield a clear cause, your doctor may recommend follow-up tests. This could include repeat stool tests, imaging studies, or even biopsies if any suspicious lesions are found during endoscopy.

8. Monitoring Symptoms: Keep track of any additional symptoms you may experience, such as changes in bowel habits, abdominal pain, weight loss, or changes in appetite. These can provide valuable information to your healthcare provider.

In conclusion, identifying the cause of occult blood in stool requires a comprehensive approach that includes thorough history-taking, physical examination, and appropriate diagnostic testing. If you have already undergone some tests, it is essential to maintain open communication with your healthcare provider to discuss the next steps based on your specific situation. They may recommend further investigations or referrals to specialists to ensure that any potential issues are addressed promptly. Always prioritize your health and seek medical advice when symptoms persist or worsen.

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