When is black stool normal and when to see a doctor? Blood in the stool

Black stool is not a common phenomenon. It occurs as one of the symptoms of the disease, but also as a manifestation of the use of certain dietary supplements or drugs.

What is stool and what does it contain?

Stool is the end product of digestion. Up to 70% of the stool consists of water, undigested food debris, dead intestinal cells and, of course, bacteria. Normally, it is coloured brown due to bile dyes.

The basics of the digestive process

The process of digestion begins in the stomach (gaster, ventriculus), which has a certain resorptive capacity. Here, a certain amount of water, salts, some drugs and alcohol are absorbed. The food is mixed by rhythmic contractions of the stomach. A chymus (food mixed with gastric juice) is formed and proceeds to the duodenum, where most of the fats are broken down.

From there it passes to the lower parts of the digestive tract. In the small intestine (intestinum tenue), the process of breaking down proteins, fats, fatty acids, amylases, vitamins and simple sugars is completed. In the large intestine (intestinum crassum, colon), the undigested food residues are found. Within about 6 to 12 hours, water, minerals and sugars are absorbed from these contents. A mucus-like secretion is added to the contents of the food residues, which glues the stool together and thus thickens it.

The natural intestinal microflora is found in the intestinal mucosa. Through its action, the process of fermentation and putrefaction takes place. The intestinal bacteria ferment fats, sugars and cellulose, which are otherwise difficult for humans to digest. As a by-product of fermentation, various gases are produced in the intestine. These include hydrogen, carbon dioxide and the gas to which we 'owe' the typical smell of faeces - methane. Proteins are in turn subject to putrefactive decomposition. The resulting product is faeces.

Stool

The appearance of the stool depends on several factors. It mainly depends on the type of food, the amount and type of fluids, medications and supplements taken, lifestyle (physical activity), age, associated diseases and current health and psychological state (diarrhoea under stress). It reveals not only the state of the digestive system, but also tells us a lot about the general state of health.

- In the case of stool, we should note, among other things, its quantity, which depends on the amount of food ingested. We cannot expect a chronically ill person who hardly takes in food to have regular stools. Patients, especially the elderly and primarily recumbent (reduced intestinal peristalsis), have a problem with constipation (obstipation).

- The consistency of the stool depends on the amount of fluid ingested and the amount of fluid resorbed in the digestive tract. Stools may have a watery, mushy or formed consistency. Bacteria and other diseases also play a role.

- The colour of the stool reveals many diseases, not only of the organs involved in digestion. The stool is normally brown in colour. In liver disease it is distinctly pale (cholic), in infections, such as salmonella, its colour is greenish. In bleeding from the upper parts of the digestive tract and other haemorrhages we see black stools.

- Defecation is called defecation and its frequency is individual. Normally, we should have stools 1-2 times every 2 days to 2-3 times a week. If someone has stools regularly more often, it is not a pathological process. If you regularly defecate once a week or less, we should consider the possibility that the reason is some disease process (celiac disease). We should be alert if its frequency changes significantly from the previous norm.

- The smell is primarily an indicator of the amount of intestinal bacteria, putrefactive processes, but also of disease processes in the body (celiac disease, infections, Crohn's disease). The more smelly the stool, the unhealthier the diet we eat. With prolonged consumption of fruits and vegetables, the smell is reduced.

- We can also find various impurities in the stool. Most often it is an admixture of fresh blood, for example, in hemorrhoids or injuries of the anus or the terminal part of the intestine. In some pathological processes, there is also an admixture of mucus (constipation, celiac disease, diverticulitis, Crohn's disease, ulcerative colitis, bacterial causes). It also contains the remains of undigested food (peelings from seeds, grapes, peppers, etc.). In young children, we sometimes find an undigested, swallowed object in the stool (a bead, part of a toy).

TIP: Stool - what should we know about it?

The most common causes of black-coloured stools

Black stools resemble tar in colour. They are usually oily, but can also have a normal consistency, changing only in colour. If it is caused by bleeding from the upper parts of the digestive system, it usually smells unpleasant. If the cause is diet, the smell is normal as usual.

Black stools in newborns

Mothers who have already had a baby will know that black stool in newborns is perfectly normal. It is called smolka (meconium). It is a black, slimy to green coloured stool, rather mushy in consistency. Since the intestine of a newborn does not contain the presence of bacteria, this stool is odourless.

Its appearance is due to all the substances that the fetus (newborn) has swallowed during its 'stay' in the womb, mainly amniotic fluid, small intestinal and skin epithelia, bile dye (bilirubin), mucus and lanugo. The amniotic fluid is reabsorbed into the blood through the fetal intestine and excreted in the urine.

It is the first stool of a newborn and in some cases may persist for a few days. If black stools persist or appear in infancy or toddlerhood, it is a pathological phenomenon and a neonatologist or paediatrician should be consulted.

Foods that stain stools black

Stools can also turn black when excessive amounts of certain foods are consumed. These are mainly foods that contain a high proportion of colouring agents. Colouring agents are either naturally present in certain fruits or vegetables or synthetic (semi-finished products).

• Beetroot
• blueberries
• liquorice
• spinach
• red wine

Medicines and nutritional supplements

• Iron (Fe)
• carbosorb (black coal)
• seaweed (as part of a detoxification treatment)

Diseases of the digestive system

Black stool (melena) is a sign of bleeding from the gastrointestinal tract, more specifically from the upper parts of the gastrointestinal tract. It is actually digested blood, which has an unpleasant smell. In bleeding from the lower parts of the digestive tract, melena does not occur. In the stool, there is an admixture of fresh blood, which, due to the location of its source, has not yet had time to digest.

- Esophageal varices are enlargement of the esophageal veins. The cause of their occurrence is most often portal (hepatic) hypertension in liver diseases such as liver cirrhosis, liver tumor, alcoholic hepatopathy. Alcoholism most often leads to the development of this disease. Bleeding from esophageal varices is a very dangerous condition, because when the esophageal blood vessel ruptures, there is a massive, difficult to stop bleeding even in a hospital setting. They are characterized by a high mortality rate. If the patient survived, the swallowed blood is digested and excreted in the stool in a typical black coloration.

- The most common cause of melena is bleeding from a gastroduodenal ulcer. A gastroduodenal ulcer is an ulcerative disease of the lining of the stomach or duodenum. It arises as a result of an erosive process on their lining due to an unhealthy diet, the use of large amounts of drugs, alcohol abuse, but is also caused by bacteria (Helicobacter pylori). As a result of the ulcer rupture, the patient vomits fresh blood (haematemesis) massively. The remaining, unvomited blood progresses through other parts of the intestine until it is excreted in the stool.

- Diseases that can cause bleeding from the stomach include stomach cancer. A malignant tumour (but also benign) can, by its pressure and overgrowth, cause a blood vessel to become perforated and rupture. The perforated blood vessel bleeds, which manifests itself in a similar way to gastric and duodenal ulcers, with vomiting of blood and severe pain in the epigastrium (stomach area).

- Inflammatory processes and the formation of ulcerations (ulcers) or tumours can also occur in the small intestine. These are usually small ulcers and a local inflammatory process that does not cause massive bleeding. Such bleeding is only manifested by the finding of haemoglobin in the stool and is called occult (hidden) bleeding. When haemoglobin is found in the stool, further diagnostic methods are used to look for the source (cancer of the small or large intestine). A tumour in the small intestine, like any other tumour in the body, can damage a blood vessel with subsequent bleeding.

Other diseases and bleeding conditions that can cause melena

• lupus erythematosus
• infectious mononucleosis
• haemophilia
• disseminated intravascular coagilopathy (DIC)
• haemolytic disease of the newborn
• haemolytic anaemia
• thrombocytopenia
• thrombocytopathies
• thrombocytopenic purpura
• von Willebrand's disease
• leukaemia
• tumour diseases
• haemorrhagic fevers

Advice in conclusion

It is important to remember that black stool does not always mean gastrointestinal bleeding. Its colouration is influenced by food components. If you had one black stool and the next one was fine, you have no problems. Its colouration was probably due to food.

Melena caused by bleeding is usually recurrent, smelly, and accompanied by other discomforts depending on the disease that caused it. The most common accompanying symptoms are, for example, pain (ulcer, tumor), other bleeding symptoms (lupus erythematosus), weakness, malaise, fatigue, decreased physical activity (anemia, leukemia), shortness of breath (anemia), fever (bacterial infections, hemorrhagic fever), and others.

In the asymptomatic course of the disease that caused melena, which persists, sooner or later symptoms caused by blood loss (weakness, malaise, fatigue, drowsiness, dizziness, pallor, sweating, low blood pressure, increased cardiac activity, fainting, collapse, darkness in front of the eyes, later disorientation, disturbances of consciousness up to symptoms of shock, and others...) appear.