Melena

A common sign of upper GI bleeding, melena is the passage of black, tarry stools containing digested blood. Characteristic color results from bacterial degradation and hydrochloric acid acting on the blood as it travels through the GI tract. At least 60 ml of blood is needed to produce this sign. (See Comparing melena to hematochezia, page 410.)

Severe melena can signal acute bleeding and life-threatening hypovolemic shock. Usually, melena indicates bleeding from the esophagus, stomach, or duodenum, although it can also indicate bleeding from the jejunum, ileum, or ascending colon. This sign can also result from swallowing blood, as in epistaxis; from taking certain drugs; or from ingesting alcohol. Because false melena may be caused by ingestion of lead, iron, bismuth, or licorice (which produces black stools without the presence of blood), all black stools should be tested for occult blood.

Emergency Actions

If the patient is experiencing severe melena, quickly take orthostatic vital signs to detect hypovolemic shock. A decline of 10 mm Hg or more in systolic pressure or an increase of 10 beats/minute or more in pulse rate indicates volume depletion. Quickly examine the patient for other signs of shock, such as tachycardia, tachypnea, and cool, clammy skin. Insert a large-bore I.V. line to administer replacement fluids and allow blood transfusion. Obtain a hematocrit, prothrombin time, International Normalized Ratio, and partial thromboplastin time. Place the patient flat with his head turned to the side and his feet elevated. Administer supplemental oxygen as needed.

History

If the patient’s condition permits, ask when he discovered his stools were black and tarry. Ask about the frequency and quantity of bowel movements. Has he had melena before? Ask about other signs and symptoms, notably hematemesis or hematochezia, and about use of anti-inflammatories, alcohol, or other GI irritants. Also, find out if he has a history of GI lesions. Ask if the patient takes iron supplements, which may also cause black stools. Obtain a drug history, noting the use of warfarin or other anticoagulants.

Physical assessment

Inspect the patient’s mouth and nasopharynx for evidence of bleeding. Perform an abdominal assessment that includes auscultation, palpation, and percussion. Perform a cardiovascular assessment to detect signs and symptoms of shock.

Medical causes

Colon cancer

On the right side of the colon, early tumor growth may cause melena accompanied by abdominal aching, pressure, or cramps. As the disease progresses, the patient develops weakness, fatigue, and anemia. Eventually, he also experiences diarrhea or obstipation, anorexia, weight loss, vomiting, and other signs and symptoms of intestinal obstruction.

With a tumor on the left side, melena is a rare sign until late in the disease. Early tumor growth commonly causes rectal bleeding with intermittent abdominal fullness or cramping and rectal pressure. As the disease progresses, the patient may develop obstipation, diarrhea, or pencil-shaped stools. At this stage, bleeding from the colon is signaled by melena or bloody stools.

CULTURAL CUE:Ask your patient about his religious and ethnic background to determine if they put him at risk for colon cancer. Colon cancer is more prevalent in Jewish people of Eastern European descent.

Esophageal cancer

Melena is a late sign of esophageal cancer, a malignant neoplastic disease. Increasing obstruction first produces painless dysphagia, then rapid weight loss. The patient may experience steady chest pain with substernal fullness, nausea, vomiting, and hematemesis. Other findings include hoarseness, persistent cough (possibly hemoptysis), hiccups, sore throat, and halitosis. In the later stages, signs and symptoms include painful dysphagia, anorexia, and regurgitation.

Esophageal varices (ruptured)

This life-threatening disorder can produce melena, hematochezia, and hematemesis. Melena is preceded by signs of shock, such as tachycardia, tachypnea, hypotension, and cool, clammy skin. Agitation or confusion signals developing hepatic encephalopathy.

Gastric cancer

Melena and altered bowel habits may occur late with gastric cancer. More common findings include insidious onset of upper abdominal or retrosternal discomfort and chronic dyspepsia that are unrelieved by antacids and are exacerbated by food. Anorexia and slight nausea usually occur, along with hematemesis, pallor, fatigue, weight loss, and a feeling of abdominal fullness.

CULTURAL CUE:Asian countries, such as Korea, China, Taiwan, and Japan, have higher rates of gastric cancer than the United States.

Gastritis

Melena and hematemesis are common in gastritis. The patient may also experience mild epigastric or abdominal discomfort that’s exacerbated by eating, belching, nausea, vomiting, and malaise.

Mallory-Weiss syndrome

Mallory-Weiss syndrome is characterized by massive bleeding from the upper GI tract due to a tear in the mucous membrane of the esophagus or the junction of the esophagus and the stomach. Melena and hematemesis follow vomiting. Severe upper abdominal bleeding leads to signs and symptoms of shock, such as tachycardia, tachypnea, hypotension, and cool, clammy skin. The patient may also report epigastric or back pain.

Mesenteric vascular occlusion

Mesenteric vascular occlusion is a life-threatening disorder that produces slight melena with 2 to 3 days of persistent, mild abdominal pain. Later, abdominal pain becomes severe and may be accompanied by tenderness, distention, guarding, and rigidity. The patient may also experience anorexia, vomiting, fever, and profound shock.

Peptic ulcer

Melena may signal life-threatening hemorrhage from vascular penetration in patients with peptic ulcers. The patient may also develop decreased appetite, nausea, vomiting, hematemesis, hematochezia, and left epigastric pain that’s gnawing, burning, or sharp and may be described as heartburn or indigestion. With hypo-volemic shock come tachycardia, tachypnea, hypotension, dizziness, syncope, and cool, clammy skin.

Small-bowel tumors

Small-bowel tumors may bleed and produce melena. Other signs and symptoms include abdominal pain, distention, and increasing frequency and pitch of bowel sounds.

Thrombocytopenia

With thrombocytopenia, melena or hematochezia may accompany other manifestations of bleeding tendency: hematemesis, epistaxis, petechiae, ecchymoses, hematuria, vaginal bleeding, and characteristic blood-filled oral bullae. Typically, the patient displays malaise, fatigue, weakness, and lethargy.

Other causes

Drugs and alcohol

Aspirin, other nonsteroidal anti-inflammatory drugs (NSAIDs), or alcohol can cause melena as a result of gastric irritation.

Special considerations

Monitor vital signs, and look closely for signs of hypovolemic shock. For general comfort, encourage bed rest and keep the patient’s perianal area clean and dry to prevent skin irritation and breakdown. A nasogastric tube may be necessary to assist with drainage of gastric contents and decompression. Prepare the patient for diagnostic tests, including blood studies, gastroscopy or other endoscopic studies, barium swallow, and upper GI series. Prepare the patient for blood transfusions as indicated by his hematocrit.

Pediatric pointers

Neonates may experience melena neonatorum due to extravasation of blood into the alimentary canal. In older children, melena usually results from peptic ulcer, gastritis, or Meckel’s diverticulum.

Geriatric pointers

In elderly patients with recurrent intermittent GI bleeding without a clear etiology, angiography or exploratory laparotomy should be considered when the risk from continued anemia is deemed to outweigh the risk associated with the procedures.

Patient counseling

Teach the patient the importance of reporting changes in bowel elimination and to undergo screening for colorectal cancer as recommended by his health care provider. Discuss the importance of avoiding aspirin, other NSAIDs, and alcohol.

Pictures

Book Source Details

• Book Title: Signs & Symptoms: A 2-in-1 Reference for Nurses
• Author(s): Springhouse
• Year of Publication: 2007
• Copyright Details: Signs & Symptoms: A 2-in-1 Reference for Nurses, Copyright © 2007 Lippincott Williams & Wilkins.

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Copyright Details: Signs & Symptoms: A 2-in-1 Reference for Nurses, Copyright © 2008 Williams & Wilkins.

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• Back to symptom: Bloody stool: Introduction (review 352 causes)
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More About This Book: Title: Signs & Symptoms: A 2-in-1 Reference for Nurses Authors: Springhouse Publisher: Lippincott Williams & Wilkins Copyright: 2007 ISBN: 1-58255-318-1

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