Hemorrhoids are swollen veins located in the anus and lower rectum that often lead to rectal bleeding. This bleeding is typically one of the first and most noticeable symptoms. Blood from a hemorrhoid is generally bright red, signifying a source close to the anal opening.
Typical Bleeding Patterns Associated with Hemorrhoids
Hemorrhoidal bleeding is characterized by bright red blood, indicating the blood is fresh and has not traveled far through the digestive tract. The blood originates from enlarged, fragile vessels located in or around the anal canal. Since the bleeding point is near the exit, the blood has minimal exposure to digestive enzymes or stomach acid that would change its color.
Internal hemorrhoids, which occur inside the rectum, often result in small amounts of blood visible on the toilet paper after wiping or a few drops noted in the toilet bowl. This bleeding is generally painless because the upper rectal lining lacks the somatic pain receptors found closer to the anal opening.
Bleeding from external hemorrhoids, which are located under the skin around the anus, can also be bright red, especially if they are irritated or if a thrombosed hemorrhoid ruptures. In these cases, the blood may streak the surface of the stool itself or be more noticeable as a drip. Straining during a bowel movement or passing a hard stool is the usual trigger that causes the thin wall of the blood vessel to break and bleed.
The Significance of Dark or Tarry Blood
Hemorrhoids do not typically cause dark or tarry blood; if blood appears dark, maroon, or black, it points to a source higher up in the gastrointestinal (GI) tract. Dark, sticky, and foul-smelling stool, known as melena, occurs when blood is broken down by digestive enzymes and stomach acid. This process oxidizes the iron in the hemoglobin, resulting in the characteristic black, tar-like appearance.
The presence of melena most commonly suggests bleeding in the upper GI tract, such as the esophagus, stomach, or the first part of the small intestine (duodenum). Common non-hemorrhoidal causes include bleeding peptic ulcers, severe inflammation of the stomach lining (gastritis), or swollen veins in the esophagus (varices).
The blood needs time to travel through the entire intestinal system for the color change to occur, which is why bleeding from the lower rectum or anus remains bright red. Rarely, if bleeding occurs slowly in the upper part of the colon, it might also appear dark before exiting. Certain medications and supplements can also mimic the appearance of dark blood, including iron supplements or products containing bismuth subsalicylate.
If dark or tarry stool is observed, it is unlikely that hemorrhoids are the cause. The change in blood color means the bleeding source is different and often more serious than a simple flare-up. Any observation of black or maroon stool warrants a thorough medical investigation to identify the true source.
When to Seek Immediate Medical Evaluation
Any instance of dark, tarry, or black stool, particularly if it is a new development, requires prompt medical evaluation to rule out a source of upper GI bleeding. This type of bleeding can signify significant blood loss that needs immediate medical attention. While bright red blood from a hemorrhoid is often self-limiting, the presence of melena should never be ignored.
You should seek immediate medical care if dark or tarry stools are accompanied by symptoms that suggest significant blood loss or a serious underlying condition. These associated symptoms include feeling dizzy or lightheaded, fainting, or experiencing severe abdominal pain. Unexplained weight loss, persistent changes in bowel habits, or vomiting blood are also concerning signs that necessitate an urgent medical consultation.
It is unsafe to assume that any rectal bleeding is simply due to hemorrhoids, especially when the blood is dark. A healthcare provider can perform diagnostic tests to accurately pinpoint the source of the bleeding. Getting a professional diagnosis ensures that a more serious condition, such as a bleeding ulcer or certain cancers, is not the actual cause.