Blood in the stool: medical explanation and diet tips

The sighting of bloody stools can be a frightening experience and should be a cause for immediate concern. However, it is important to understand that this symptom can be caused by a variety of causes of varying severity, from harmless lesions to serious illnesses. An accurate diagnosis and appropriate treatment is essential, and a specialist gastroenterologist can help. In addition to treatment, a healthy diet plays a key role in alleviating symptoms and restoring gastrointestinal health.

This article provides a comprehensive medical explanation of the possible causes of bloody stools, diagnostic procedures and detailed dietary advice to help manage the symptoms.

Medical explanation of bloody stools

Blood in the stool indicates bleeding at some point in the digestive tract. The location and nature of the bleeding may indicate the cause. The colour of the blood provides key information:

• Bright red blood (haematochezia): This type of bleeding usually originates from the lower intestine, most commonly the colon, rectum or anus. As the blood does not spend much time in the digestive tract, it retains its fresh red colour.
• Dark red, clotted blood: This bleeding can also originate in the colon, but the transit time is longer so the blood has time to clot.
• Black, pitchy stools (melena): This phenomenon is a sign of bleeding in the upper digestive tract (oesophagus, stomach, small intestine). The blood turns black in contact with stomach acid and digestive enzymes.

Possible causes of bloody stools

Many conditions can cause blood in the stool. The most common causes are detailed below, moving from the less serious to the more serious.

Harmless but unpleasant causes

• A nodularity (nodus haemorrhoidalis): Dilatation of the veins around the anus, often causing bright red bleeding, especially after defecation on toilet paper or in the toilet bowl. Pain is not always an accompanying symptom unless a thrombosis develops.
• Rectal tear (fissura ani): Chapping of the skin of the anus caused by hard stools or straining. It is characterised by sharp, stabbing pain during defecation and subsequent bright red bleeding.
• Rectal ulcer (solitary rectal ulcer): A rarer condition that can also cause bleeding and pain.

Inflammatory and infectious conditions

• Inflammatory bowel diseases (IBD):

- Ulcerative colitis (ulcerative colitis): Typically a chronic inflammation with bloody, pus-like diarrhoea that starts in the rectum and spreads to the colon.

- Crohn's disease: It can affect any part of the digestive tract and, although less common, can also cause bloody stools, accompanied by abdominal pain and weight loss.

• Infectious colitis (inflammatory colitis): Infections caused by certain bacteria (e.g. _Campylobacter, Shigella, Salmonella, E. coli_) or parasites can cause acute bloody diarrhoea. _Clostridium difficile_ infections can also cause severe diarrhoea, sometimes bloody, often after a course of antibiotics.
• Diverticulitis: Inflammation or bleeding of small bumps (diverticula) on the wall of the large intestine. Diverticular bleeding may be sudden, painless, but may involve the discharge of large amounts of blood.
• Ischaemic colitis: A blood supply disorder of the large intestine that causes abdominal pain and bloody stools, typically in older age.

Cancer and other causes

• Polipok: Benign growths on the lining of the colon, which may bleed over time and some may become malignant. The bleeding is usually hidden (occult) but sometimes visible.
• Colorectal cancer (colorectal carcinoma): Bloody stools can be one of the most important warning signs, especially if they are associated with faecal habitus changes, abdominal pain or unexplained weight loss.
• Angiomas (angiodysplasia): More common in older age, abnormal, fragile blood vessels in the intestinal wall can cause bleeding.
• Upper GI bleeding: Stomach ulcers, oesophagitis or bleeding from varices (dilated veins) may result in black stools (melena). In cases of heavy bleeding, the stools may be dark red because of faster bowel movements.

When should we see a doctor?

In all cases where you notice blood in your stools, it is recommended that you seek medical advice to find out the exact cause. However, there are so-called alarming or warning symptoms that require immediate medical attention:

• Persistent or recurrent bloody stools
• Discharge of large amounts of blood
• Pitch black stools
• Abdominal pain, fever, chills
• Unexplained weight loss
• Changes in bowel movements (e.g. new-onset constipation or diarrhoea)
• Signs of anaemia: paleness, weakness, dizziness, choking

From Endomedix Gastroenterology Centre specialists are equipped with modern diagnostic tools to quickly and accurately identify the cause of complaints.

Diagnostic procedures

To make the diagnosis, the doctor will first take a detailed medical history and perform a physical examination, including a finger prick examination of the rectum (rectal digital examination, RDV). The following tests may then be required:

• Laboratory tests: CBC (to detect anaemia), inflammatory parameters (CRP, sedimentation), liver and kidney function, coagulation parameters.
• Stool analysis: To detect hidden (occult) bleeding, infectious agents (culture) or _Clostridium difficile_ toxin.
• Endoscopic examinations: These are the most important procedures for identifying the source of bleeding.

- Colonoscopy (colonoscopy): It is used to review the entire large intestine and the last part of the small intestine. It can also be used for histological sampling (biopsy) and removal of polyps. It is the gold standard for screening and diagnosis of colorectal cancer.

- Gastroscopy (gastroscopy): If black stools (melena) or upper gastrointestinal bleeding are suspected, the esophagus, stomach and horseshoe casing are examined.

• Imaging techniques: A CT angiogram or MR scan may also be needed to pinpoint the location of the bleeding more accurately, especially in the case of active, heavy bleeding.

Dietary advice for bloody stools

Proper nutrition is essential to support the healing process. It is important to emphasise that diet alone is not a substitute for medical treatment, but it can make a significant contribution to symptom relief and intestinal regeneration. Dietary recommendations may vary depending on the underlying cause.

General nutritional guidelines

• Fluid replacement: With bleeding and possible diarrhoea, the body loses a lot of fluid. To avoid dehydration, drink plenty of fluids, at least 2-2.5 litres a day. Water, herbal teas (e.g. chamomile, calendula) and diluted, non-carbonated fruit juices are recommended.
• Easily digestible foods: Give preference to easily digestible, low-fat foods to protect the gastrointestinal tract. Eat cooked, steamed or fried foods instead of fried in high fat.
• Frequent, small meals: Instead of three big meals a day, eat five to six times less. This puts less strain on the digestive system.

Diet depending on the underlying cause

For duodenal ulcers and rectal rupture

These conditions are often caused by hard stools and straining, so the aim is to soften the stools and ensure regular bowel movements.

• High fibre intake: The fibre absorbs water, increases the bulk of the stool and makes it loose. Gradually increase your fibre intake to 25-30 grams/day.

- Sources of soluble fibres: oatmeal, barley, apples, pears, carrots, citrus fruits, plantain seed husks. These form a gel that slows digestion and helps bowel movements.

- Sources of insoluble fibres: wholegrain cereals, nuts, seeds, green beans, cauliflower. These increase the weight of the stool.

• Drink plenty of fluids: Fibres can only be beneficial if they are sufficiently hydrated. With a fibre-rich diet, 2-3 litres of fluid per day is essential.

For inflammatory bowel diseases (IBD)

During the active, inflammatory stages of IBD, the intestinal tract is extremely sensitive, so a low-fibre, low-stress diet is needed.

• Foods to avoid during the active phase:

- Raw vegetables and fruit (their peel can be particularly irritating).

- Bloating foods (cabbage, pulses, onions, cauliflower).

- Wholemeal bakery products, oilseeds.

- Hot, spicy foods, carbonated drinks, alcohol, coffee.

- Fatty, heavy foods.

• Recommended foods during the active phase:

- Boiled potatoes, rice, hulled cereals.

- Steamed, pureed, low-fibre vegetables (e.g. carrots, pumpkin).

- Peelless fruit prepared as compote (e.g. apples, peaches).

- Lean meats (chicken breast, turkey breast) and fish steamed or boiled.

- Low-fat dairy products (if not lactose intolerant).

During the symptom-free (remission) period, the diet can be gradually expanded, but it is worth finding out which foods cause complaints based on individual sensitivity.

Diverticulosis and diverticulitis

• Diverticulosis (asymptomatic condition): A high-fibre diet with plenty of fluids is recommended for prevention, as described for haemorrhoids. Contrary to previous misconceptions, eating seeds, nuts, popcorn does not increase the risk of inflammation in most cases.
• Diverticulitis (inflammatory condition): In the acute inflammatory phase, a liquid diet followed by a pulpy, low-fibre diet is needed to calm the intestinal tract. After the inflammation has subsided, fibre intake can be gradually increased.

What to do if you suspect colorectal cancer?

Nutrition plays a key role in preventing colorectal cancer. It is recommended to eat a diet rich in fibre, vegetables and fruit, and to reduce the consumption of red meat and processed meat products. If you experience bloody stools and suspect cancer, the most important thing is to have a gastroenterological examination as soon as possible. Until a diagnosis is made, follow general dietary recommendations.

Summary and next steps

Bloody stools are a serious symptom and can have many causes. Don't try to diagnose yourself at home and don't delay seeking medical attention. An accurate diagnosis is essential for effective treatment. Visit Endomedix Gastroenterology Centre experienced professionals and modern diagnostic facilities ensure that the cause of your complaints is identified as soon as possible and you receive a personalised treatment plan.

Following the right diet is key to recovery. Dietary advice may vary depending on the underlying cause, but hydration and sparing the intestinal tract are always important. You should consult a specialist who can help you with the right diet and treatment.