Approach to melena and hematemesis: Clinical sciences

Melena, or stool containing partly broken down blood, and hematemesis, or vomit containing blood, are most commonly seen in patients who present with acute upper gastrointestinal bleeding, which is typically defined as the gastrointestinal portion that’s proximal to the ligament of Treitz. It’s important to keep in mind that melena may sometimes be caused by slow bleeds from the lower gastrointestinal tract. Melena presents as black or tarry stools and can be seen in variable amounts of blood loss.

On the other hand, hematemesis can present as frank, bright red bloody emesis suggesting a recent or ongoing bleed that might be moderate to severe; or coffee-ground emesis, which suggests that the bleeding is limited or the blood is older. The presentation of emesis can help you start localizing the bleed, since coffee-ground emesis usually develops when blood comes in contact with gastric acid, such as a peptic ulcer; while bright red blood can indicate either a brisk bleed or that the blood didn’t come in contact with gastric acid, such as an epistaxis draining posteriorly, oropharyngeal or esophageal bleeds.

When assessing a patient with melena or hematemesis, you should first perform an ABCDE assessment to determine whether your patient is unstable or stable. If the patient is unstable, first stabilize the airway, breathing, and circulation. You might need to intubate the patient to protect the airway. Next, obtain IV access and start IV fluids. Additionally, patients who are acutely hemorrhaging might require blood product transfusions. Finally, put your patient on continuous vital sign monitoring, including pulse oximetry, blood pressure, and heart rate.

Once these important steps are done, you can move on to obtaining a focused history and physical exam, as well as labs like CBC and CMP. History might reveal massive hemorrhage, or lesser but brisk bleeding. On the flip side, the physical exam might show signs of hemodynamic instability, like hypotension and tachycardia. As a result of severe blood loss and contraction, initial labs may show decreased hemoglobin along with elevated BUN to creatinine ratio. Now, since these patients are acutely bleeding, the next step is an emergent upper endoscopy to locate and identify the source of bleeding.

Alright, let’s talk about some important causes of acute bleeding. First up, there are aortoenteric fistulas, which are rare, but very dangerous. An aortoenteric fistula is a connection between the GI tract and the aorta. A patient might present with an initial, smaller, "herald bleed" manifested by hematemesis. The smaller bleed is then followed by massive bleeding and exsanguination, which might occur soon after it, or might even occur up to several weeks later. On a physical exam, you might feel a pulsatile abdominal mass or hear an abdominal bruit. Finally, endoscopy usually reveals an ulcer or erosion at the site of bleeding or an extrinsic pulsatile mass. So, if you see these findings, you can diagnose an aortoenteric fistula.

Next cause of bleeding is called Mallory-Weiss tear, which is a tear in the distal esophagus or upper part of the stomach. These patients typically report severe epigastric or back pain and have a history of vomiting or retching. The endoscopy is very important here. So, if it shows a gastroesophageal mucosal laceration, you can diagnose a Mallory-Weiss Tear.

Let’s switch gears and talk about other types of vascular lesions, including angiodysplasia, vascular ectasia, and Dieulafoy's lesion. Now, in this case, your patient might tell you that they have noticed new cutaneous lesions. Additionally, a physical exam might reveal signs of these lesions such as venous malformations, cutaneous hemangiomas, or occasionally telangiectasias.

Once again, endoscopy will help you make the final diagnosis. On endoscopy, you might find small ectatic vessels in the vascular ectasia, cherry-red spots in the angiodysplasia, or an ulcer with raised vessels in Dieulafoy's lesion. So, if you see any of these, you can diagnose vascular lesions as a cause of GI bleeding.

The final cause of severe upper gastrointestinal bleeding are gastroesophageal varices. These patients might have a history of hepatic conditions like cirrhosis. Additionally, the physical exam usually shows signs of chronic liver disease such as jaundice, splenomegaly, or ascites. However, endoscopy is crucial in making a diagnosis. If you see swollen, enlarged veins within the esophageal or gastric lumen, you can diagnose gastroesophageal varices.