Blood in Stool: Definition and Causes

Definition and Causes

The presence of blood in the stool is a symptom of various gastrointestinal disorders, indicating disturbances related to the integrity of the gastrointestinal tract lining.

Bleeding can be detected either by the patient themselves or in the laboratory. If blood in the stool is not visible to the naked eye, it is considered occult; if the person sees blood, it is considered overt.

Sometimes the disorder is discovered during preventive examination through laboratory tests. In some cases, symptoms of the disease may be absent, and the only sign remains the presence of blood in the stool.

As for the diseases:

  • Anal fissure
  • Crohn’s disease
  • Rectal prolapse
  • Hemorrhoids
  • Duodenal ulcer
  • Colitis
  • Irregular passage of food through the intestines
  • Paraproctitis
  • Abnormal growth of tumors in the stomach and intestines
  • Rectal cancer

If you notice similar symptoms, consult your doctor. Do not self-medicate, as it poses a risk to your health!


To determine the diagnosis, the doctor collects the medical history and patient complaints. The specialist focuses on identifying the frequency and nature of stools, the type of abdominal pain (if present), medications taken (including NSAIDs and antibiotics), recent trips to other areas and countries, the presence of tumors and inflammatory diseases in the digestive system, and the presence of bloody impurities in the stool.

Then, the doctor performs a physical examination – palpating the abdomen and identifying tender areas. This is followed by an examination of the anal region. The doctor examines the area around the anus, considering the presence of hemorrhoids, inflammatory processes, and tumors. They may detect narrowing of the intestinal passage, fissures, and other disorders associated with the integrity of the intestines and tissue proliferation.

The next step is laboratory diagnosis – stool and blood tests. Through comprehensive blood analysis, the doctor determines the severity of anemia and detects signs of inflammatory processes in the body.

Then comes the instrumental diagnosis stage. The choice of examination method depends on the initial diagnosis:

  • Radiographic imaging using barium ingestion to detect ulcers and tumors.
  • Rectal examination in case of suspicion of rectal diseases.
  • Examination of the area around the anus using an anoscope.
  • Colonoscopy to explore the large intestine.
  • Radiological and optical methods (rectomanoscopy and colonoscopy) are necessary, especially if there is suspicion of a tumorous process, where a tissue sample can be taken for study.

Ultrasound examination of abdominal organs and the abdominal cavity is a non-invasive diagnostic method that allows imaging the size and shape of internal organs, identifying tumors, and evaluating the condition of lymph nodes surrounding the intestines using an ultrasound scanner.

If necessary, other procedures are performed and consultations with other specialists are scheduled.

Types of Blood in Stool

  1. Bright red blood drops – indicative of rectal injury.
  2. Bright red blood streaks in brown stool – a sign of colon injury.
  3. Dark mixed blood with stool evenly – indicates injury to the first sections of the large intestine.
  4. Black stool in droplet form – appears in cases of small intestine, stomach, or esophageal injury.

Accurately identifying the type of blood in the stool helps the doctor determine the initial diagnosis and guide further investigation in the right direction.

Causes of Blood in Stool and Common Associated Diseases

Anal fissure:

  • Pain in the anal area during and after defecation.
  • Bleeding during defecation in the form of droplets on top of the stool or traces on toilet paper.
  • Distinct changes in the anal area upon examination by a doctor, aiding in precise diagnosis.


  • Abnormal increase in the size of hemorrhoidal masses (venous plexuses under the rectal lining).
  • Internal masses protruding from the hemorrhoids during defecation.
  • Bleeding from hemorrhoids during defecation (either as red blood spots in the stool or as spots or pockets without fecal masses).
  • Presence of swollen external hemorrhoidal masses.
  • In some cases, itching, burning in the anal area, and mucous discharge from the rectum.

Rectal prolapse:

  • Inability to control bowel movements or occurrence of constipation.
  • Protrusion or protrusion of the rectum from the anal opening during defecation, which can be self-correcting or require manual correction.
  • Feeling of incomplete bowel emptying.
  • Bleeding during defecation in case of rectal lining injury.

Anal skin tags (acrochordons):

  • Sharp growths in the anal area, protruding above the level of the anus. Associated with human papillomavirus (HPV). Symptoms include:
  • Bleeding in the form of red lines during bowel movements if the tags are present inside the anal canal and are injured during stool passage.
  • Itching, burning, and discomfort in the anal region.

Diverticular disease:

  • Presence of one or more diverticula (small disruptions in the intestinal wall). In severe cases, bleeding may occur, which can be light or dark red, sometimes containing blood clots.

Crohn’s disease:

  • Abdominal pain.
  • Fever.
  • Weight loss.
  • Increased frequency of bowel movements with bleeding (either as droplets of blood or as a mixture of blood with stool).

Ulcerative colitis:

  • Bleeding in the stool.
  • False urges to defecate.
  • Increase in the number of bowel movements per day.
  • Fever.
  • Weight loss.

Colon cancer:

  • Bleeding and/or mucous discharge with stool (most common and prominent in early stages and present in 90% of patients).
  • Diarrhea and constipation.
  • Tenesmus (false urge to defecate), accompanied by bleeding, pus, or mucus.
  • Partial bowel obstruction.
  • Weight loss.

Treatment for conditions where blood in the stool is detected aims at two main goals:

Stopping the bleeding:

  • Use of medications that promote blood clotting.
  • Restricting food intake.
  • Recommendation to drink cold water.
  • In case of ineffectiveness of conventional methods, surgical intervention may be required to stop bleeding surgically.

Basic treatment:

  • After stopping the bleeding, basic treatment is directed at preventing its recurrence.
  • In the case of peptic ulcers, antifungal and acid-reducing medications are prescribed.
  • In the case of hemorrhoids, venotonic preparations are used.
  • In the case of anal fissure, wound healing agents and others are used.
  • In some diseases, the only treatment is surgery, such as tumor or polyp removal, and excision of non-healing anal fissures, etc.

After that, treatment is carried out to prevent a high rate of bleeding recurrence. In case of decreased hemoglobin levels due to bleeding, anemia treatment is carried out for at least a month. In case of bleeding shock, compensation for lost blood volume, correction of organ functions, etc., are shown.