Hidden blood in the stool: causes, diagnosis and treatment options

Hidden blood in the stool, which is invisible to the naked eye, can be frightening for many people, but there are many, often benign, reasons for this. However, it is important not to take it lightly, as it can be the first sign of more serious digestive diseases, such as tumours. Fortunately, modern medicine offers increasingly sophisticated diagnostic and treatment methods to detect and correct the problem. In this article, we will explain in detail what you need to know about hidden bleeding, how to investigate it and what therapeutic options exist today. Our aim is to provide clear and reassuring information to help you Endomedix Gastroenterology Centre patients and all stakeholders.

The term 'hidden bleeding' means that a small amount of blood is present in the stool that does not visibly change its colour or consistency. This blood loss is often chronic and can lead over time to iron deficiency anaemia, with symptoms of fatigue, weakness, pallor and reduced physical exertion. Because the symptoms are common, many people do not even think of a digestive problem.

The underlying causes of hidden bleeding can be very varied, ranging from banal problems to serious illnesses. An accurate diagnosis is crucial, as treatment always depends on the underlying cause. Thanks to advances in modern medicine, procedures and drugs are now available that can effectively target the various sources of bleeding, be it inflammation, ulcers, polyps or even tumours.

Possible causes of hidden bleeding

Bleeding at any stage of the digestive tract can appear as a hidden form in the stool. The most common causes can be divided into the upper and lower parts of the digestive tract. It is important to understand that the source of bleeding determines the subsequent therapeutic strategy.

Upper gastrointestinal bleeding

This includes lesions of the oesophagus, stomach and the initial part of the small intestine (horseshoe).

• Stomach and duodenal ulcers (peptic ulcers): One of the most common causes is. Ulcers are often caused by bacterial infection with _Helicobacter pylori_ or long-term use of non-steroidal anti-inflammatory drugs (NSAIDs). Acid gastric juice irritates the damaged mucous membrane, which can lead to bleeding. Treatment is based on reducing acid production with proton pump inhibitor (PPI) drugs and eradication of the _H. pylori_ bacteria with antibiotics.
• Esophagitis and erosions: Gastric acid reflux disease (GERD) causes stomach acid to flow back into the oesophagus, where it can cause swelling and inflammation. These areas may also bleed. Again, the treatment is high-dose PPI therapy.
• Esophageal varices (varix): They form in the oesophagus in cases of severe liver disease, most commonly cirrhosis. These dilated blood vessels can easily rupture and cause significant bleeding, although this is less common in a hidden form. Their treatment requires special drugs (e.g. terlipressin) and endoscopic surgery.

Lower gastrointestinal bleeding

It is caused by diseases of the lower small intestine, the large intestine and the rectum.

• Colon polyps and tumours: Perhaps the most important and most notable cause of hidden bleeding. Polyps are benign lesions that grow on the intestinal wall, some of which can develop into malignant tumours over time. The surface of both polyps and tumours is vulnerable and may cause mild bleeding during passage of faeces. Stool blood testing is therefore an essential method of screening for colorectal cancer. Polyps detected early can be removed endoscopically, preventing the cancer from developing.
• Diverticulosis: Small diverticula form on the wall of the large intestine, which can become inflamed (diverticulitis) or bleed. Diverticular bleeding is often sudden and heavy, but it can also cause chronic, hidden bleeding.
• Inflammatory bowel diseases (IBD): Crohn's disease and ulcerative colitis are associated with chronic inflammation of the intestinal wall, which can cause ulcers and bleeding. Treatment is with immunosuppressive drugs such as 5-aminosalicylates, steroids or modern biological therapies.
• Hemorrhoids (nodus haemorrhoidalis): Although haemorrhoids most often cause fresh, red bleeding on the surface of the stool, they can also occasionally cause hidden bleeding. It is a benign lesion, but symptoms should not be automatically attributed to it, and it is essential to rule out more serious causes.

Diagnosis of hidden bleeding

As hidden bleeding can be caused by a number of different conditions, an accurate diagnosis is essential to choose the right therapy. The investigation usually consists of several steps.

• A sediment blood test: The first step is to detect the presence of hidden blood. The most modern and reliable method is the faecal immunochemistry test (FIT), which specifically detects human haemoglobin. It is more sensitive and specific than older, guaiac-based tests. If the test is positive, further tests are needed to identify the source of the bleeding.
• Laboratory tests: A complete blood count helps to assess the extent of anaemia. In addition, liver and kidney function and inflammatory parameters (e.g. CRP) can also provide important information.
• Endoscopic examinations: These are the most important procedures to determine the exact location and cause of bleeding.

- Gastroscopy (gastroscopy): It is used to examine the oesophagus, stomach and horseshoe casing. It also allows the identification of ulcers, inflammations, tumours and histological sampling (biopsy).

- Colonoscopy (colonoscopy): It can be used to view the entire colon and the last part of the small intestine. During the scan, the doctor can detect and even remove polyps (polypectomy), preventing cancerous degeneration. Modern, high-resolution endoscopes and image-enhancing technologies (e.g. NBI, LCI) help to detect even the smallest lesions.

- Capsule endoscopy: A modern, gentle method of examining the small intestine. The patient swallows a small capsule with a camera, which passes through the alimentary canal and takes thousands of pictures. It is particularly useful if a gastroscopy and colonoscopy cannot find the source of bleeding. Advances in artificial intelligence (AI) are also bringing breakthroughs in this area: AI-based software can now select abnormal images with an accuracy of over 99%, significantly shortening the time to diagnosis.

Treatment of hidden bleeding and future prospects

The treatment of hidden bleeding always depends on the underlying cause. Therapy can be drug, endoscopic or surgical.

Current drug therapies

• Proton pump inhibitors (PPIs): The cornerstones for the treatment of gastric and duodenal ulcers and oesophagitis caused by reflux. They reduce the production of stomach acid, helping the mucosa to heal.
• _Helicobacter pylori_ eradication therapy: A combination of PPI and two types of antibiotics is used to kill the bacteria and prevent the ulcer from recurring.
• Anti-inflammatory drugs for IBD: 5-aminosalicylates (5-ASA), corticosteroids and immunosuppressants (e.g. azathioprine) reduce inflammation of the intestinal wall, thus stopping bleeding.
• Biological therapies: They have revolutionised the treatment of inflammatory bowel diseases. These targeted drugs (e.g. infliximab, adalimumab) block specific inflammatory molecules and can be effective in severe cases.
• Vasoconstrictors (vasoconstrictors): Drugs used to treat oesophageal bleeding, such as terlipressin, reduce the pressure in the portal circulation.
• Somatostatin analogues (e.g. octreotide): They reduce the blood supply to the intestine, so they can be effective for certain types of bleeding, such as angiodysplasias (small vessel malformations).

Promises of the future: what will 2025 bring?

Although the introduction of specific new „hidden bleeding drugs” in the form of a single, universal agent is not expected by 2025, research in gastroenterology is evolving dynamically. The focus is on more targeted, personalised therapies and further refinement of diagnostics.

• More targeted biological therapies: Newer biological drugs and small molecule drugs (e.g. JAK inhibitors) with more specific mechanisms of action are emerging in the treatment of inflammatory bowel diseases. These may have fewer side effects and greater efficacy, so that the treatment of inflammation-induced bleeding is further improved.
• The role of the microbiome: More and more is known about the role of gut bacteria (the microbiome) in digestive health. In the future, microbiome-based therapies, such as stool transplants or targeted probiotics, may play a role in the treatment of inflammatory conditions, indirectly reducing the risk of bleeding.
• Developments in cancer therapy: Immunotherapies and targeted oncology drugs are gaining ground in the treatment of colorectal cancer. Although these do not directly treat the hidden bleeding, they eliminate the source of the bleeding by more effectively containing the tumour.
• Artificial intelligence in diagnostics: As mentioned above, AI is already helping to diagnose capsule endoscopy. In the future, it is expected to assist the doctor in detecting polyps in real time during conventional colonoscopy („computer-assisted diagnosis”), increasing the accuracy of the examination and reducing the number of missed lesions.

How can the Endomedix Gastroenterology Centre help?

The investigation of hidden blood in faeces is a complex task that requires an experienced specialist and modern instrumentation. From Endomedix Gastroenterology Centre has both to provide the highest level of care to its patients.

At our centre, the examination starts with a thorough discussion with the patient, where we assess symptoms, medical history and risk factors. Then, based on the clinical picture, we will suggest the necessary diagnostic steps, be it laboratory tests, gastroscopy or colonoscopy.

We are proud of our modern, state-of-the-art endoscopic park, which allows us to detect even the smallest lesions. Colonoscopies are performed under general anaesthesia at the request of our patients, making the examination completely painless and comfortable. Any polyps found during the examination are removed immediately, effectively preventing the development of colon cancer.

If the hidden bleeding is caused by a condition requiring medication, our specialists will use the latest international guidelines to set the necessary therapy and monitor its effectiveness. Visit Endomedix Gastroenterology Centre is committed to patient-centred, empathetic and highly professional care. Please do not hesitate to contact us if you have digestive complaints or if your stool has been screened for hidden blood. A timely diagnosis can save lives.