Rectal bleeding is usually identified by a small amount of bright-red blood that appears in the stool, on toilet paper, or in the toilet bowl. There are multiple causes of rectal bleeding.1 To get rid of rectal bleeding for good, it is important to diagnose the actual cause of the bleeding.
Rectal bleeding is not lethal. However, it may indicate some serious underlying conditions like rectal cancer.
Causes of Rectal Bleeding
The following conditions may be related to rectal bleeding.
The fistula is an abnormal burrowing channel from the rectum to the skin around the anus.2 Usually, a white discharge oozes out from the opening, but rarely, bleeding may start from it. A fistula may be associated with chronic inflammation or Crohn's disease.
Hemorrhoids or piles are the build-ups of swollen vessels and muscle fibers in the rectal area. These can be external or internal. Internal hemorrhoids are not painful, but they may cause bleeding.3
Hard stool and the urge to defecate may lead to anal fissures and bleeding. This is a similar condition to having cracked lips in winter. Nerve endings and vessels are exposed, which may cause pain and bleeding.
These are pockets that protrude from the bowel wall. They balloon out over a period of several years due to recurrent high pressure in the rectum. On rare occasions, diverticulosis may lead to heavy bleeding which requires hospitalization.
Proctitis and colitis
Either the rectum or colon can be inflamed. Multiple disorders may cause the inside surface of the bowel to bleed. There may be rectal urgency, diarrhea, or cramps that may lead to rectal bleeding. If inflammation is restricted to the rectum, it is called proctitis; if the colon is involved, it is called colitis.
Polyps and cancer
Polyps are small benign growths in the colon. When polyps increase in size, they bleed. Certain types of polyps can turn into cancer. Colon cancer is curable at an early age. In older adults, colon cancer is a common condition leading to rectal bleeding.
Protrusion of rectum
Rectal tissue weakens in older adults, which may lead to protrusion of the rectum anus. The protruded rectum can be a source of rectal bleeding. This condition is called rectal prolapse.
Certain other rare conditions may cause rectal bleeding, like vitamin K deficiency, hemophilia, and thrombocytopenia.
How does rectal bleeding appear?
The color and consistency of blood may indicate the source of bleeding.
- Bright-red blood means bleeding is from the lower colon or rectum.
- Dark red or maroon blood means bleeding is from the upper colon or small intestine.
- Dark and tar-like blood indicates bleeding from the stomach.
It is necessary to diagnose the actual cause of rectal bleeding including anal cancer.4
Age, sex, color, frequency, and extent of the bleeding can be important. Eating habits and constipation should be considered. All of these factors may provide clues, but advanced tools are used for a positive diagnosis.
A physician can inspect the anal area to look for hemorrhoids and tears. A finger exam can also reveal tender issue or tumors inside.
There are specific microscopes available for colon exams. A physician may choose a rigid anoscope or a flexible sigmoidoscope to view the colon. The process is called a flexible sigmoidoscopy. A colonoscopy allows a thorough exam of the entire colon.5
A barium enema is a complementary exam that uses liquid barium inserted into the rectum. An X-ray highlights tumors, benign growths, and diverticuli.
If the bleeding is suspected of coming from the stomach, the doctor can pass a nasogastric tube to remove the contents and check to see whether the bleeding is from the stomach or not.
- Haydock S, Walker G. Rectal Bleeding. Acute Med A Symptom-Based Approach. Published online May 4, 2022:376-382. doi:10.1007/9781139600354.056
- Arpornsujaritkun N, Supsamutchai C, Thirapanich W, Hiranyatheb P, Biadul N. Rare cause of massive lower gastrointestinal bleeding due to primary isolated ilio-rectal fistula. J Surg Case Reports. 2017;2017(4). doi:10.1093/JSCR/RJX074
- Lohsiriwat V. Hemorrhoids: From basic pathophysiology to clinical management. World J Gastroenterol. 2012;18(17):2009. doi:10.3748/WJG.V18.I17.2009
- Cocorullo G, Tutino R, Falco N, et al. Rectal bleeding and prolapse… not always benign diseases rather anal cancer. The importance of a correct decision making since primary care. G di Chir. 2016;37(3):133-135. doi:10.11138/gchir/2016.37.3.133
- Metcalf J V, Smith J, Jones R, Record CO. Incidence and causes of rectal bleeding in general practice as detected by colonoscopy. Br J Gen Pract. 1996;46(404):161. Accessed September 2, 2022. /pmc/articles/PMC1239576/?report=abstract