Dr. Francis SANWO

Gastrointestinal (GI) bleeding is usually categorized as either melena or hematochezia.

Melena refers to black stools, while hematochezia refers to fresh, red blood in your stool. This blood might be mixed in with your stool or come out separately. Hematochezia usually comes from the colon, while melena usually comes from a higher point in your GI tract.

Both melena and hematochezia are symptoms, not actual conditions. Many conditions can cause either type of bleeding. Some of these conditions are serious, so it’s important to follow up with your doctor immediately if you notice blood in your stool.

Hematochezia

Hematochezia is usually a bright red color. Remember, hematochezia is caused by bleeding in your colon, which is fairly close to your anus. The blood only travels a short distance, so it’s still fresh by the time it leaves your anus. You might notice it mixed in with your stool, though it can also come out separately.

In addition, hematochezia tends to cause more minor bleeding than melena does. Other symptoms that might accompany hematochezia include: diarrhea, change in bowel habits, abdominal pain, fever and weight loss.

Melena   refers to the dark black, tarry feces that are associated with upper gastrointestinal bleeding. The black color and characteristic strong odor are caused by hemoglobin in the blood being altered by digestive enzymes and intestinal bacteria. The black, tarry stools are easy to distinguish from the brighter red associated with hematochezia. The blood is usually jet-black, similar to ink from a black ballpoint pen. Your stools might also look or feel sticky.

This blood is darker because it has to travel farther down your GI tract. By the time it reaches your anus, it’s been deoxygenated, which removes its bright red color. In addition to melena, you might also experience hematemesis, which refers to vomiting blood.                                                                                  

Most cases of black stools are from eating black foods or iron supplements (this could also cause green stool).

The most common condition causing black stools is a bleeding ulcer.

Black stools caused by blood indicate a problem in the upper digestive tract.

Blood in the stool can be detected through a stool test.

Black stool along with pain, vomiting, or diarrhea is a cause to see a doctor right away.

If blood in the stool is suspected, you should contact your doctor as soon as possible.

 Foods that are dark blue, black or green may also cause black stools.

If you're seeing black stools and can trace it back to a food you ate, that's okay. However, a doctor should be consulted immediately if black stools cannot be traced back to a food, an iron supplement.

The most common cause of melena is peptic ulcer disease. However, any bleeding within the upper gastrointestinal tract or the ascending colon can lead to melena. Melena may also be a complication of anticoagulant medications, such as warfarin.

Causes of "false" melena include iron supplements, blood swallowed as a result of a nose bleed (epistaxis), and blood ingested as part of the diet, as with consumption of black pudding (blood sausage). Melena is considered a medical emergency as it arises from a significant amount of bleeding. Urgent care is required to rule out serious causes and prevent potentially life-threatening emergencies.

What causes them?

Both hematochezia and melena have different potential causes.

Hematochezia

Hematochezia originates lower in your GI tract, usually in your colon.

Several things can cause bleeding in your lower GI tract, including: internal hemorrhoids, diverticular disease, such as diverticulitis, anal fissures, colon cancer, ischemic colitis, inflammatory bowel disease (IBD), neoplastic polyps and benign tumors

In children, hematochezia is usually caused by IBD (inflammatory bowel disease), Meckel’s diverticulum, or juvenile polyps.

Melena

Melena is caused by bleeding higher up in your GI tract. This may be due to: peptic ulcers, gastric or esophageal varices, gastritis and stomach cancer . Another cause of stomach ulcers is the long-term use of pain medications known as NSAIDs (nonsteroidal anti-inflammatory drugs). NSAIDs can irritate the stomach by weakening the lining's ability to resist acid made in the stomach. For this same reason, NSAIDs have an adverse effect on Crohn's disease and ulcerative colitis. NSAIDs include common over-the-counter drugs such as ibuprofen, naproxen sodium, and aspirin. Some NSAIDs are prescribed by physicians. Stomach ulcers caused by NSAIDs usually heal after the offending drug is discontinued.

Some newborns have melena from swallowing blood during delivery.

How are they diagnosed?

Your doctor can usually differentiate between melena and hematochezia by simply looking at a stool sample. Based on the color of the blood, additional testing to narrow down a diagnosis may be done.

Hematochezia

If you have hematochezia, your doctor will likely start with a colonoscopy. This involves inserting a small tube with a camera through your rectum. The device will give a view of your lower GI tract, including your colon and pinpoint where the blood is coming from. During the procedure, a small tissue sample can be taken for additional testing.

Other tests used to diagnose the cause of hematochezia include: Enteroscopy. You’ll swallow a small capsule containing a camera that produces images of your GI tract.

Barium X-ray. Your doctor will have you swallow a contrast material called barium. It might also be  inserted  into your rectum. This will help your GI tract show up on an X-ray.

Angiography. This involves injecting dye into a vein to make blood vessels visible on a CT scan or X-ray.

Laparotomy. This is a more invasive test that involves surgically opening your abdomen to find the source of bleeding.

Melena

Similar tests are also use to diagnose the underlying cause of melena. Other test that may also be used are:

Esophagogastroduodenoscopy (EGD). A small tube with a camera and light attached to it is inserted through your mouth and down your esophagus. This will help your doctor check for signs of bleeding higher up in your GI tract.

Blood, stool, or breath test. Your doctor may ask for a stool sample, take a blood sample, or schedule a breath test to check for signs of an infection, including those caused by Helicobacter pylori.

How are they treated?

Hematochezia and melena usually have different causes, but their treatments are very similar. Your doctor will start by focusing on stopping the bleeding.

Regardless of your symptoms, it’s best to talk to your doctor if you notice any signs of blood in your stool.