Many people experience the symptom of blood in their stool and thus want to know what disease causes bloody stool. Many people become restless and unnecessarily tense because they do not know what disease causes this condition. Experts from Shanghai Guoji Proctology Hospital have provided the following analysis for a wide range of patients:
Blood in the stool is one of the main manifestations of anal and rectal diseases, as well as a local symptom of digestive tract or systemic diseases. The presence of blood mixed with feces during excretion, or bleeding before or after defecation, or even the passage of pure blood or blood clots, is referred to as hematochezia (bloody stool).
There are many reasons for blood in the stool, but most belong to proctological diseases. Based on the nature of the bloody stool and accompanying symptoms, it may be related to the following anal and rectal diseases:
1. **Internal Hemorrhoids**: Intermittent bleeding is the main symptom. After continuous bleeding for a period, there may be a break, meaning not every bowel movement results in bleeding. The blood is bright red, either dripping or spurting like an arrow, not mixed with stool, and without pain.
2. **Anal Fissure**: The blood is bright red, usually in small amounts, often staining the toilet paper. It is accompanied by severe anal pain during defecation, which slightly eases after defecation and then becomes severely painful again, with prolonged pain lasting several hours. However, in clinical practice, some patients with anal fissures only experience mild pain or no pain at all, and also present with dripping fresh blood.
3. **Colonic Polyps**: More common in young adults, followed by children. The amount of bleeding varies. Colonic polyps generally cause no pain. When the polyp is large, low in position, or when the bleeding is significant, the blood does not mix with the stool but rather adheres to the surface of the stool. If the polyp is higher up, the blood may mix with the stool.
4. **Ulcerative Colitis and Crohn's Disease**: Both are non-specific intestinal inflammations of unknown cause, more commonly seen in young people. Mucoid bloody stool is the main symptom, with blood, pus, and mucus present in the stool. Generally, the amount of bleeding is not excessive, accompanied by abdominal pain, diarrhea, or alternating diarrhea and constipation, or with systemic symptoms such as weight loss, fatigue, low fever, and anemia.
5. **Colorectal Cancer** (including colon cancer and rectal cancer): Painless bloody stool, generally with less bleeding, darker blood that is not fresh, often mixed with pus and mucus, adhering to the surface of the stool or mixed with the stool.
6. **Melena or Tar-like Stool**: Primarily seen in upper digestive tract diseases, such as esophageal, gastric, and duodenal inflammation, ulcers, injuries, vascular lesions, and tumors. Note that ingesting large amounts of animal blood, animal liver, or phenolphthalein laxatives causing black stools should not be mistaken for bloody stool.
7. **Other Intestinal Diseases**: Bloody stool accompanied by fever, abdominal pain, and acute onset is commonly seen in bacterial dysentery, epidemic hemorrhagic fever, hemorrhagic necrotizing enteritis, amoebic colitis, etc.
This analysis provides insight into various conditions that can cause blood in the stool, helping individuals understand potential underlying issues and seek appropriate medical care.