Blood in Stool

The presence of blood in the stool is a symptom of various digestive system diseases. It may indicate a mild pathology or a severe condition, so it should be evaluated by a physician.

Symptoms and Causes

Blood in the stool is a symptom of a digestive system disease. Although it is usually a cause for concern and a common reason for consultation, it is not always indicative of a serious condition.

Depending on the origin of the bleeding, there are different types of blood in stool:

Rectal bleeding (rectorrhagia): fresh blood is expelled through the rectum, maintaining its natural color because it has not been digested.
Hematochezia: fresh blood is excreted along with the stool.
Melena: the stool is black because it contains digested blood.

The prognosis of blood in stool depends on the severity of the underlying cause. In most cases, it is a transient symptom indicative of a mild, treatable condition. Nevertheless, consultation with a specialist is recommended, especially if bleeding persists, to allow for an accurate and timely diagnosis.

Symptoms

The main symptom is a change in the normal appearance of the stool due to the presence of blood:

Rectorrhagia: although fresh blood may be detected in the stool, it is more commonly observed on toilet paper or occurs without defecation.
Hematochezia: stools appear red or maroon, sometimes darker due to mixing with feces.
Melena: stools are black and shiny (tarry in appearance), with a characteristic foul odor and pasty consistency.

The presence of blood in the stool may be accompanied by other symptoms related to the underlying disease. The following signs warrant prompt evaluation by a specialist:

Persistent blood in stool.
Bloody mucus in the stool.
Abdominal pain.
Change in stool color.
Anal or perianal pain when defecating or sitting for prolonged periods.
Fecal incontinence.
Weight loss.
Low blood pressure.
Dizziness.

Causes

Some of the main causes of blood in the stool include:

Rectorrhagia: bleeding originates from the lower gastrointestinal tract, usually the colon, rectum, or anus. The most frequent causes are:

- Constipation: the most common cause in children.
- Hemorrhoids: inflamed veins in the distal rectum or anus.
- Anal fissure: a tear in the anal lining.
- Colitis: inflammation of the colon characterized by frequent diarrhea, i.e., soft or liquid stools more than four times per day.
- Polyps: benign growths in the tissues lining the colon or rectum.
- Diverticulosis: presence of diverticula (small pouches of tissue) in the colon.
- Crohn’s disease: chronic inflammatory bowel disease that can affect any part of the gastrointestinal tract, from mouth to anus, but most commonly the ileum (distal small intestine).
- Ulcerative colitis: chronic inflammatory disease affecting the mucosa lining the rectum and colon.
- Colon cancer: malignant tumors in the colon, the longest portion of the large intestine.
- Rectal cancer: presence of malignant cells in the rectum, the terminal segment of the intestine.

Hematochezia: typically results from lower gastrointestinal bleeding, i.e., from the small intestine, colon, rectum, or anus. The causative diseases are often the same as those listed for rectal bleeding.
Melena: bleeding originates from the upper digestive system, usually the esophagus, stomach, or duodenum. Common causes include:

Gastric ulcers: lesions of the stomach or duodenal mucosa.
Gastritis: inflammation of the stomach lining.
Esophageal varices: dilated esophageal veins due to increased portal venous pressure carrying blood from the intestine to the liver.
Stomach cancer.
Esophageal cancer.

Risk Factors

The risk of blood in the stool is higher in the following scenarios:

Age: more frequent in individuals over 50 years old.
Constipation: hard, dry stools can damage the mucosa during evacuation.
Certain medications: aspirin, non-steroidal anti-inflammatory drugs (NSAIDs), and anticoagulants may promote bleeding.
Chronic colon diseases.
History of colon cancer.
Pelvic, colorectal, or prostate radiotherapy.

Complications

Blood in the stool may lead to:

Anemia: chronic bleeding reduces iron and hemoglobin levels.
Severe hemorrhage: in serious cases, prolonged and abundant bleeding can cause critical blood loss (hypovolemic shock).

Which Specialist Manages Blood in Stool?

Blood in the stool is managed by the Gastroenterology.

Diagnosis

The fecal occult blood test is the standard procedure to detect non-visible blood in stool. Two methods are commonly used:

Fecal immunochemical test (FIT): stool samples are treated with specific antibodies that detect human hemoglobin.
Guaiac test: stool is treated with a chemical agent to reveal the presence of blood. Certain medications must be suspended, and dietary restrictions are required beforehand.

This test confirms the presence of blood in the stool but not the cause. Further diagnostic procedures may include:

Anal inspection: to identify lesions such as hemorrhoids or fissures.
Blood analysis: provides information on overall health and detects anemia.
Colonoscopy: a flexible tube with a camera is inserted through the anus to visualize the colon, particularly the distal gastrointestinal tract. Commonly used to diagnose diverticulosis, Crohn’s disease, ulcerative colitis, or colorectal cancer.
Gastroscopy: an upper endoscopy in which a camera-equipped tube is introduced through the mouth to examine the stomach. Used to diagnose gastritis, ulcers, polyps, or tumors in the esophagus or stomach.

Treatment

There is no specific treatment for blood in the stool; management focuses on addressing the underlying cause. The most frequent approaches are:

Hemorrhoids: usually improve with warm sitz baths or topical medication; surgery is only needed in severe cases.
Anal fissures: respond well to topical medications or suppositories.
Polyps: removed surgically.
Colitis: responds to anti-inflammatory drugs and corticosteroids.
Diverticulosis: managed with observation and dietary modifications to prevent complications; antispasmodics and analgesics are used for recurrent episodes; surgery is reserved for severe cases.
Ulcerative colitis: typically managed pharmacologically with aminosalicylates, corticosteroids, immunomodulators, or biologic antibodies; surgery to remove the colon is considered if medication is insufficient.
Crohn’s disease: patients usually improve with dietary modifications and anti-inflammatory medications; surgery may be necessary to remove affected areas or repair fistulas.
Gastritis: treated with acid-suppressing medications and antibiotics if infection is present; dietary modifications support recovery.
Gastric ulcers: treated with healing medications and antibiotics.
Cancer: often requires a combination of surgery with chemotherapy, radiotherapy, or immunotherapy.