Gastrointestinal bleeding: Pathology review

A 30-year-old male named Joseph came to the emergency department because of sharp chest pain radiating to his back. He recently graduated from medical school and has been celebrating for the past week at local bars. He says that he was drinking to the point of vomiting and blacking out. He thinks his pain began after a particularly intense night of vomiting and retching. His vital signs show no abnormalities. On the other hand, a 54-year-old lawyer called Lance has been noticing blood in his stool for the past 2 weeks. As he describes the problem, he mentions that there are “streaks of bright red blood” on top of the stool and didn’t notice any pain during bowel movements. Also, he reports a marble-sized, soft mass at the anus that can be pushed back into the anal canal. He denies abdominal pain, weight loss, or a history of colon cancer.

Now both people have gastrointestinal bleeding, but with different presentations. Gastrointestinal bleeding can be divided into upper and lower GI bleeding. Upper GI bleeding arises above the ligament of Treitz, also called the suspensory ligament of the duodenum, and it includes bleeding from the esophagus, stomach, or duodenum. Typical presentation includes hematemesis, or vomiting of blood; ‘coffee ground’ vomitus, which suggests that the blood has been oxidized by the acid in the stomach so that the iron in the blood has turned dark; and melena, which refers to black, tarry stools. On the other hand, lower GI bleeding arises below the ligament of Treitz and includes bleeding from the small intestine past the ligament of Treitz, large intestines, rectum, and anus. Typical presentation includes hematochezia, which is fresh blood passing through the anus which may or may not be mixed with stool.

Now, since these individuals are losing blood, they can develop anemia, or they can even become hemodynamically unstable. In mild hypovolemia, when they lose less than 15% of the blood volume, these individuals can experience resting tachycardia. In moderate hypovolemia, when they lose from 15% to 40% of the blood volume, they can experience orthostatic hypotension; and finally, in severe hypovolemia, when they lose over 40% of the blood volume, these individuals will develop hypotension.