Makindo Medical Notes.com

Melaena refers to the passage of black, tarry stools, typically indicative of upper gastrointestinal (GI) bleeding. The dark coloration occurs due to the digestion of blood as it passes through the GI tract. Melaena is a serious clinical sign that suggests significant blood loss and requires urgent medical evaluation.

Causes of Melaena

• Peptic Ulcer Disease (PUD): The most common cause of upper GI bleeding, typically associated with Helicobacter pylori infection or NSAID use. Ulcers in the stomach or duodenum can erode into blood vessels, leading to bleeding.
• Gastritis: Inflammation of the stomach lining due to H. pylori infection, alcohol, or prolonged NSAID use can result in bleeding and melaena.
• Oesophageal Varices: Dilated veins in the oesophagus, often secondary to portal hypertension in cirrhotic patients, can rupture and cause life-threatening upper GI bleeding.
• Gastr oesophageal Reflux Disease (GORD): Severe inflammation or ulceration in the oesophagus due to acid reflux can occasionally result in bleeding.
• Malignancy: Gastric or oesophageal cancers can ulcerate and bleed, leading to melaena.
• Mallory-Weiss Tear: A tear in the mucosal lining of the oesophagus or stomach, often due to forceful vomiting or retching, can cause bleeding and result in melaena.
• Vascular Lesions: Conditions such as angiodysplasia (abnormal blood vessels) can cause bleeding in the upper GI tract.

Clinical Presentation

• Appearance:Melaena typically presents with black, tarry stools that have a characteristic foul odor due to the digestion of hemoglobin. Other associated symptoms may include
• Abdominal pain: Common in patients with peptic ulcer disease or gastritis.
• Haematemesis: Vomiting blood, which may indicate a more proximal source of bleeding (e.g., oesophageal varices or gastric ulcer).
• Fatigue and weakness: These symptoms may indicate significant blood loss and resultant anemia.
• Shock: In severe cases, patients may present with hypotension, tachycardia, pallor, and signs of hypovolemic shock.

Diagnostic Approach

• History and Physical Examination: Key to assessing the onset, duration, and frequency of symptoms. It is important to inquire about the use of NSAIDs, alcohol, history of liver disease, and previous GI bleeding.
• Fecal Occult Blood Test (FOBT): May be used to detect the presence of blood in the stool in cases of suspected but unclear GI bleeding.
• Blood Tests: Full blood count (FBC) to assess for anaemia and hematocrit levels. Coagulation profile (PT, INR) to assess for coagulopathy. Liver function tests (LFTs)
• Endoscopy: Upper GI endoscopy is the gold standard for diagnosing the source of bleeding. It allows visualization of the oesophagus, stomach, and duodenum, and therapeutic interventions (e.g., cauterization, banding) can be performed during the procedure.
• Imaging:: CT angiography can be useful in detecting active bleeding if endoscopy is not immediately available or in cases where the source of bleeding is unclear.

Management of Melaena: Initial Resuscitation

• Shock or significant blood loss, intravenous fluids or blood transfusion is critical.
• Place two large-bore intravenous (IV) lines and begin fluid resuscitation with crystalloids (e.g. N-saline or lactated Ringer's).
• Blood transfusion target haemoglobin >7 g/dL in stable patients or >9 g/dL in high-risk patients.
• PPI: IV PPIs (e.g. pantoprazole) are recommended to reduce gastric acidity and stabilize clots in peptic ulcer bleeding.
• Octreotide: A somatostatin analog used in suspected variceal bleeding to reduce portal pressure.
• Antibiotics: For cirrhotic patients with oesophageal varices, prophylactic antibiotics (e.g., ceftriaxone) are recommended to prevent infection.
• Endoscopic Haemostasis: Upper GI endoscopy is performed to identify and treat the source of bleeding. Techniques include:
  • Injection therapy (e.g. epinephrine) to induce vasoconstriction.
  • Thermal coagulation or laser therapy to stop bleeding from ulcers.
  • Endoscopic band ligation or sclerotherapy for bleeding varices.
• In cases where endoscopic therapy fails, or there is uncontrolled bleeding, surgical intervention may be necessary.
• Options include oversewing of bleeding ulcers, resection of the bleeding segment, or shunt surgery in the case of variceal bleeding.

Treatment of Underlying Causes

• Patients with Helicobacter pylori infection should receive eradication therapy (a combination of PPI, clarithromycin, and amoxicillin or metronidazole).
• Long-term PPI therapy for patients with recurrent ulcers or those on chronic NSAIDs.
• Management of cirrhosis and portal hypertension in patients with variceal bleeding (e.g., beta-blockers, band ligation).

Prevention of Recurrence

• For patients with variceal bleeding, non-selective beta-blockers (e.g., propranolol) are recommended for secondary prevention.
• Patients with peptic ulcers should avoid NSAIDs and alcohol, and adhere to long-term PPI therapy if necessary.