Blood in the stool is a symptom that should be checked with a doctor. However, there is not always something bad to hide behind it. Various causes can be considered for the reddish residues in the faeces, such as hemorrhoidal disease, intestinal diverticula or inflammation. Black stool, also called tarry stool (malena), is caused by contact of the blood with the hydrochloric acid in the stomach. It therefore indicates bleeding in the upper digestive tract.
Different types of blood in the stool
Blood in the feces is not always directly recognizable to those affected. For example, it may be hidden, that is, not visible to the naked eye, which is called “occult blood” in technical terms. In a so-called tar chair (Meläna), the chair is colored abnormally black and shiny. You can easily see bright red blood on or in the stool.
Bleeding source and appearance of blood residues
Different types of blood in the stool are differentiated depending on the bleeding source. In a tarry stool, bleeding occurs in the upper gastrointestinal tract, that is, between the mouth and the duodenum. The amount of blood is more than about 100 milliliters. A few hours after the bleeding event, patients drop a shiny black stool. The color arises when hydrochloric acid from the stomach breaks down the blood.
If the origin is in the lower area of the digestive tract, starting from the empty intestine (jejunum), the blood is visible to those affected as a light red admixture or layer. This form is typical, for example, in the case of a hemorrhoidal disease.
With occult blood that is not visible to the eye, the bleeding is very small. Special inspection methods are used to make the residues visible. The source can be found in the entire digestive tract. In colorectal cancer screening, “occult blood” is also “searched for” in order to identify possible colorectal cancer at an early stage.
The stool can also turn dark or black if there is no bleeding. For example, taking iron, bismuth and coal supplements or eating blueberries or beetroot will cause the color to turn dark. Black bowel movements must always be taken seriously and as soon as possible clarified by a doctor.
Causes of tar chair
Various illnesses can be responsible for the complaints. Possible causes of tar stool, where the bleeding source is usually in the upper digestive tract, are ulcers (ulcers), inflammation of the esophagus (esophagitis), esophageal varices (varicose veins of the esophagus), violent vomiting or gastric carcinoma.
The tar chair usually arises from the fact that the bleeding source is located above the small intestine. However, it can also occur if intestinal bacteria break down the hemoglobin due to prolonged contact or if the intestinal passage is slowed down, from which the "black" hematin forms and the feces become discolored.
Inflammation of the esophagus can also be considered. Irritation caused by viruses, fungi or burns, for example, can lead to bleeding in the mucous membrane. This is mostly visible in the form of a tar chair.
Portal vein hypertension caused by liver disease often leads to the formation of esophageal varices. These are varicose veins in the esophagus, which are formed by the high pressure in this area. The varices can tear, which can lead to easier bleeding, which can be recognized as blood in the stool. In severe cases, violent vomiting of blood (hematemesis) occurs, which is a life-threatening situation.
The situation is similar with the so-called "Mallory-Weiss syndrome". With this disease, the mucous membrane between the stomach and esophagus is irritated by violent vomiting, gagging or chronic reflux oesophagitis (often in alcoholics) so that there are tears that can bleed. With lighter forms, the stool turns dark, with severe courses, vomiting of blood begins.
In severe cases, stool discoloration can indicate gastric cancer. Not least for this reason, it is imperative that blood admixtures and tar stools are absolutely clarified by a doctor as soon as possible.
Cause gastric ulcer
A gastric ulcer is often accompanied by anorexia, feeling of fullness, stomach pressure, nausea and vomiting. Complications may include hematemesis or blood in the stool. With an amount of blood that is greater than 100 milliliters, tarry stools and bloody vomiting (or so-called "coffee grounds break") occur. The black color of the feces is caused by the breakdown of hemoglobin (red blood pigment). Smaller amounts, if they come from the area of the stomach, are not visible to the eye (occult blood).
Reasons for blood admixtures
If the blood comes from the middle or lower digestive tract, it becomes visible through deposits or additions in the stool. This so-called "hematochecia", ie a "fresh" bleeding, can in rare cases also come from the upper digestive section. This is possible, for example, if those affected take medication that inhibits hydrochloric acid. A very quick passage through the entire digestive tract (with an empty stomach) can also trigger hematochecia in the upper digestive tract.
Tumors in the small or large intestine can be the reason for the additions. However, these do not necessarily have to be malicious. For example, polyps are mostly benign mucosal growths that can bleed. Inflammatory bowel diseases such as Crohn's disease or ulcerative colitis due to the constant inflammatory stimulus are also possible causes.
Diverticulum and inflammation of the colon
Older people are more likely to develop so-called diverticula. These are protuberances of the intestinal wall, preferably in the large intestine. They can become inflamed (diverticulitis) and start to bleed as a result.
Pseudomembranous colitis is also conceivable. This is an inflammation of the large intestine (colitis), which arises, for example, after long-term antibiotic intake. The physiological intestinal flora is destroyed, causing antibiotic-resistant bacteria to spread, which in turn produce toxins and cause inflammation.
Fissures and hemorrhoids
More common and much less critical causes of blood on the anus or stool are anal fissures and hemorrhoids. Anal fissures are mucosal tears in the anal area with an unknown cause, with constipations (constipations) promoting the development of the unpleasant disease. Typically, bright red blood appears in the feces or on the toilet paper, in addition to which, when the injuries heal, violent anus burning and itching usually occur.
Light red blood admixtures can also indicate hemorrhoidal disease, usually only hemorrhoids. Everyone has these knot-shaped extensions, also called artriovenous vascular pads. Together with the inner and outer sphincters, they help seal the intestine outwards.
However, it is not uncommon for the spongy vascular pads to become pathologically enlarged, which leads to symptoms such as burning and itching on the anus, anus pain, blood in the faeces, constant foreign body sensation in the anus area and a feeling of incomplete emptying. In this case, we speak medically of a hemorroid disease.
The visit to the doctor
Blood admixtures should be clarified by a doctor to determine the source. This also applies if there are no other accompanying symptoms. If other complaints such as pain during bowel movements, night sweats or nausea and vomiting occur, a doctor should be consulted as soon as possible. Also, in the event of unwanted weight loss, medical clarification is urgently required. Anemia (anemia) often arises, especially with prolonged or intensive bleeding in the digestive tract, which must be treated.
Diagnostics and examination methods
As part of the medical history, the patients are asked about the type of bleeding or whether it is tar stool or hematochecia. Furthermore, it is clarified whether previous diseases such as hemorrhoidal diseases, stomach ulcers, polyps in the intestine, diverticula, chronic inflammatory bowel diseases or possibly alcoholism are present. The further procedure is usually based on this.
The examination methods used include stool diagnostics, gastrointestinal surgery, rectoscopy (rectal surgery), X-rays and nuclear medicine procedures in which radioactive substances are introduced into the body (scintigraphy). If necessary, blood is drawn in order to examine it for pathogens and to rule out anemia.
If the admixture is not visible to the naked eye, the diagnosis is usually a coincidence. The blood is determined by the so-called haemoccult test, which can also be used at home: on three consecutive days, patients put some stool on test papers and hand them over for evaluation in the doctor's office. If the test is positive, blood has been detected in the samples. In this case, further examinations are necessary, for example with the aid of a colonoscopy.
Treatment for blood residues
The treatment options depend on the cause and the extent of the bleeding. In the case of hemorrhoids, a high-fiber diet and sufficient hydration must be ensured to combat existing constipation.
Regular intake of psyllium can make the stool softer, making it easier to go to the toilet every day. These measures also apply to anal fissures. Surgical intervention may be necessary for massive forms.
Another effective home remedy for constipation is dried fruit (plums, figs, dates etc.), alternatively e.g. Plum or sauerkraut juice helps to get your digestion going. With hemorrhoids, cold washes have proven effective after bowel movements to relieve the itching and to treat the affected blood vessels.
Extracts of witch hazel (witch hazel) are well suited to naturally minimize bleeding and inflammation in the area of the anus. A hip bath with essential oils is a boon for enlarged, painful hemorrhoids.Instructions for oil hip bath
- Give each two drops of cypress and chamomile oil
- and a drop of peppermint oil in a half-full bowl of warm water
- Take a hip bath for 5 to 10 minutes
- Then pat the anal area thoroughly but carefully
Acute bleeding in the gastrointestinal tract can be stopped using endoscopic procedures. This includes, for example, the so-called "hemoclip", which closes the bleeding source. Injection methods are often used, which cause the vessels to contract. A laser can clear up the bleeding point. It is possible to prevent hemorroidal bleeding or esophageal variceal bleeding with the help of a so-called “rubber band ligation”. After the treatment of acute bleeding, the focus is on the underlying disease.
Various preventive measures can be used to prevent blood admixtures in the stool or its causes. The basis is a healthy, low-fat, high-fiber and vitamin-rich diet that is low in animal products. Adequate hydration, in the form of still water, should also be ensured. Alcohol and smoking should be avoided and obesity should be reduced.
With the help of regular recovery phases and relaxation exercises, stress reduction should be aimed for. Because negative stress can, for example, promote the development of a gastric ulcer. Proven methods include yoga, autogenic training and progressive muscle relaxation. (sw, nr)
Author and source information
This text corresponds to the specifications of the medical literature, medical guidelines and current studies and has been checked by medical doctors.
Susanne Waschke, Barbara Schindewolf-Lensch
- Hans-Ulrich Comberg (ed.): General medicine: 39 tables, Thieme, 2004
- J. Durst; G. Neumann; K. Schmidt: "Occult blood in the stool", in: German medical weekly, Volume 101 Issue 12, 1976, Thieme Connect
- Hermann Füessl; Martin Middeke: Dual series - medical history and clinical examination, Thieme, 2018
- Jürgen Stein, Till Wehrmann: Functional diagnostics in gastroenterology: medical standards, Springer, 2006
- Andreas Hirner; Kuno Weise: Surgery: Section by Section, Thieme, 2004