Both conditions involve symptoms of gastrointestinal bleeding, though a major difference is that hematochezia often presents as bright red blood in the stool, while melena appears as black, tarry stool.

The causes for both may differ slightly. For example, hemorrhoids often cause hematochezia, while peptic ulcers cause melena. Still, some causes overlap, and both conditions can sometimes indicate a serious underlying condition.

Therefore, seeking medical attention when someone experiences gastrointestinal bleeding is crucial. Treatment usually focuses on addressing the underlying cause.

Keep reading to learn more about hematochezia versus melena, including differences in symptoms, causes, diagnosis, and treatment.

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Both hematochezia and melena are symptoms of gastrointestinal bleeding. They can both result in hypovolemia, a reduction in circulating blood volume. Symptoms of hypovolemia can include:

Although some other symptoms may overlap, there are also differences. These include the below.

Hematochezia symptoms

Hematochezia denotes bright red blood that appears around the anus, the opening at the end of the intestinal tract through which stools pass.

Symptoms may include:

Melena symptoms

Melena refers to black, tarry, sticky stools, which frequently have a strong odor. Additional symptoms may include:

Hematochezia or melena may have life threatening causes.

The two symptoms have some causes in common. However, most of the causes of hematochezia are generally conditions that affect the lower gastrointestinal tract, or large intestine. This is mainly the colon and rectum, the lowest part of the colon.

Conversely, most of the causes of melena are conditions that affect the upper gastrointestinal tract. This is the esophagus (food pipe), stomach, and duodenum. The latter is the upper part of the small intestine.

Hematochezia causes

Causes that affect the colon and rectum include:

  • cancer
  • hemorrhoids, which are swollen veins in the lower rectum
  • diverticular disease, a condition where small pouches form and push outward through the colon wall
  • arteriovenous malformations, which are a tangle of blood vessels connecting arteries and veins that disrupt blood flow
  • ischemic colitis, which refers to inflammation in the colon due to reduced blood flow
  • inflammatory bowel disease, which refers to long-term conditions that produce inflammation in the digestive tract

Sometimes, hematochezia can come from the upper gastrointestinal tract. When this happens, causes may include peptic ulcer, which refers to bleeding from an ulcer in the stomach or duodenum. This may stem from the long-term use of aspirin or nonsteroidal anti-inflammatory drugs.

Another upper gastrointestinal cause of hematochezia involves esophageal varices, which are enlarged veins in the esophagus.

Melena causes

Upper gastrointestinal tract causes may include:

Additionally, melena may stem from blood disorders presenting as excessive bleeding, such as hemophilia.

Diagnostic tools will sometimes overlap. Those for hematochezia often focus more on the lower gastrointestinal tract, and techniques to diagnose melena tend to focus more on the upper gastrointestinal tract.

Hematochezia diagnosis

A medical history may include asking questions to determine if a person has signs of fresh bleeding, such as bright red blood on toilet paper.

Additionally, diagnosis can entail the following:

  • Digital rectal exam: This is a procedure where a doctor inserts a gloved finger into the rectum to feel for anything atypical.
  • Lab tests: These may include blood tests to see if anemia is present.
  • Endoscopy and colonoscopy: These procedures involve the insertion of a small tube with a camera into the esophagus or colon, respectively.
  • Nuclear red blood scan: This imaging test uses radioactive material to tag red blood cells and find the source of bleeding.
  • CT scan: This is another type of imaging test that helps a doctor find anything atypical which could be causing bleeding.

Melena diagnosis

A medical history may entail asking questions to determine if black, tarry stools are present. A doctor may also perform some of the tests above.

Diagnosis may include nasogastric lavage. This procedure involves pumping the stomach contents to gauge the severity of blood loss. Another diagnostic tool for melena is an endoscopy.

For both conditions, if significant blood loss has occurred, a critically important treatment goal involves bringing the blood volume to typical levels quickly. This involves intravenous fluid administration, which means giving fluid in a vein. It may also include a blood transfusion.

Following this, the aim of treatment is to address the underlying cause. Treatment methods also differ between hematochezia and melena. For example, treatment of hematochezia may include surgery for colon cancer or following a high fiber diet for diverticulitis.

In contrast, treating melena may involve medications to decrease acidity in the stomach for peptic ulcers.

While both may signify gastrointestinal bleeding, there are several differences between hematochezia and melena. Hematochezia presents as bright red blood that usually comes from the lower gastrointestinal tract. Melena involves black, tarry stools that often come from the upper gastrointestinal tract.

Examples of conditions that cause hematochezia include hemorrhoids and diverticular disease, while those that cause melena include peptic ulcers and GERD.

Diagnostic tools for hematochezia may necessitate lower gastrointestinal tract procedures, such as a colonoscopy and digital rectal exam. In contrast, those for melena may focus on upper intestinal tract procedures, such as a nasogastric lavage and endoscopy.

Treatment entails addressing the underlying cause, such as eating a high fiber diet for diverticular disease or taking acid-reducing medication for peptic ulcers. However, if a person bleeds enough to cause hypovolemia, this requires prompt treatment with intravenous fluids.