Gastrointestinal bleeding: Pathology review

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Case Study0:00–0:56

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.

Pathology0:56–2:29

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.
Okay, let’s start with upper GI bleeding! In this video, we’ll cover esophagitis, esophageal varices, esophageal perforation, Boerhaave syndrome, Mallory-Weiss syndrome, and Dieulafoy lesion.

Esophageal Varices2:29–3:26

Keep in mind that gastritis, peptic ulcers, and gastric cancer can also be common causes, but we will go over them in the “Gastroesophageal reflux disease, gastritis, and peptic ulcers” video.
Okay, so esophageal varices are dilated submucosal veins in the lower third of the esophagus. A high yield fact for your exams is that esophageal varices are most often caused by portal hypertension, which is usually a consequence of cirrhosis, therefore, they are common in individuals who had hepatitis or are chronic alcohol users.
If the varices rupture, which can occur when eating hard food, or during vomiting, they can cause life-threatening hematemesis.
The next one is esophageal perforation, which can be subdivided into iatrogenic esophageal perforation, which occurs during endoscopic procedures; and non-iatrogenic esophageal perforation, which can be caused by spontaneous rupture, trauma, foreign body ingestion, and malignancy.

Esophageal Perforation3:26–4:11

Once esophageal perforation occurs it can lead to media-stinitis, or inflammation of the mediastinum; pneumo-mediastinum, which is basically a pocket of air surrounding the heart; and subcutaneous emphysema, which is the presence of air in the subcutaneous tissue.
Subcutaneous emphysema occurs due to dissecting air and the clinical presentation includes crepitus on palpation of the neck region and chest wall.

Boerhaave Syndrome4:11–4:44

Speaking of esophageal perforation, let’s also talk about Boerhaave syndrome. So, you have to know that this is a transmural, distal esophageal rupture of the esophagus caused by a sudden increase in intraesophageal pressure, like from straining or vomiting.
It can be diagnosed using a chest x-ray, which can show left-sided effusion or pneumomediastinum; or by esophagram, which is used to confirm the diagnosis.
As far as treatment goes, the standard of care for Boerhaave syndrome is surgery. The next one is Mallory-Weiss syndrome, also known as gastro-esophageal laceration syndrome.

Mallory-Weiss Syndrome4:44–5:52

Mallory-Weiss syndrome can also occur due to forceful vomiting that increases intra abdominal pressure, but instead of perforation or rupture, there’s longitudinal, partial thickness tears in the mucosa at the gastroesophageal junction.
You should also remember that it can be precipitated by coughing, hiccuping, abdominal trauma, or abdominal straining. Individuals with Mallory-Weiss syndrome can be asymptomatic or they can present with painful hematemesis.
In about half of the cases, this syndrome is associated with hiatal hernias, which are considered as a strong predisposing factor.
It’s also associated with alcoholism and bulimia nervosa. As far as diagnosis goes, the gold standard is endoscopy that helps show the tears in the esophageal mucosa.
In the past, barium swallow was used to detect hematomas or streaks in the esophagus; however, it's no longer recommended as it has low sensitivity and can interfere with endoscopy.
In most cases, Mallory-Weiss syndrome spontaneously resolves, but if there’s severe bleeding, these individuals require endoscopic techniques to obtain hemostasis.A rarer cause of upper GI bleed is Dieulafoy lesion or exulceration simplex Dieulafoy, which is a rare condition characterized by an unusually dilated arteriole that erodes the overlying mucosa and starts bleeding.

Dieulafoy Lesion5:52–7:02

The treatment is usually a combination of epinephrine injection with thermocoagulation or hemostatic clips placement. Now let’s move on to common causes of lower GI bleeding, in this video, we will go over intestinal angiodysplasia, intestinal ischemia, and hemorrhoids.
However, remember that the most common cause is diverticulosis and the most important one to catch is colorectal cancer.
You can check out our video on “Diverticular disease of the colon,” and “Colorectal polyps and cancer” videos to learn more.
Inflammatory bowel disease can be a bit tricky. Crohn's disease can affect any part of the GI tract so it could present with signs and symptoms of upper and lower GI bleed, while ulcerative colitis is limited to the colon and rectum, so it always presents with signs of lower GI bleed.

Intestinal Angiodyspl.7:02–7:59

You can learn more about them in our “Inflammatory bowel disease” video. Okay so let’s go over intestinal angiodysplasia which is the 2nd most common cause of lower GI bleed after diverticulosis.
These are small, dilated blood vessels in the mucosa and while they are most commonly found in the right colon, they can appear anywhere in the GI tract.
Although the exact cause is unknown, they are suspected to be the result of obstructed venous drainage. Increased levels of growth factors like VEGF may also play a role, especially when they arise outside the large intestine.
Most people with intestinal angiodysplasia are asymptomatic, but mild or even severe bleeding can occur. The diagnosis is often made incidentally during a colonoscopy in asymptomatic people, or during an endoscopic exploration for lower GI bleeding due to an unknown cause.

Intestinal Ischemia7:59–11:42

The treatment is endoscopic obliteration of the affected vessels, but this is not necessary in asymptomatic individuals.
Okay, moving on to Intestinal ischemia which is caused by anything that reduces intestinal blood flow, like arterial or venous occlusion, or vasospasm of blood vessel that supplies the small or large intestine.
Usually, the mucosal layer is the first to be damaged in gastrointestinal ischemia or infarction, but if there’s a sudden occlusion of major vessels transmural infarction can also occur.
Now, when intestinal ischemia affects the small intestine, it’s called mesenteric ischemia, and sometimes, intestinal angina.
On the flip side, when it affects the large intestine it’s called colonic ischemia, or ischemic colitis. Acute mesenteric ischemia is usually caused by embolic occlusion of the superior mesenteric artery, which is the artery that branches off the aorta and supplies most of the small intestine, including the cecum, ascending colon, hepatic flexure, and most of the transverse colon.
As ischemia progresses necrosis occurs, causing severe abdominal pain, which can be followed by hematochezia. A high yield finding is red currant jelly stool, which is when the necrotic mucosa slough off and mix with blood and mucus to take on a jelly like consistency.
On the other hand, chronic mesenteric ischemia is usually caused by athero-sclerotic narrowing of the celiac trunk, superior mesenteric artery, or inferior mesenteric artery.
On physical exam, individuals present with mild abdominal pain or no pain at all, but they complain about severe epi-gastric or peri-umbilical pain 30-60 minutes after eating.
This occurs because athero-sclerotic arteries are not able to dilate in response to increased blood requirements, which are needed for the digestion and absorption of nutrients.
Also, chronic mesenteric ischemia is associated with weight loss because these individuals avoid food due to severe postprandial pain.
It’s important to note that mesenteric ischemia can also occur after volvulus or intussusception, where arteries that supply the small intestine become compressed.
The gold standard in the diagnosis of mesenteric ischemia is CT angiography because it can help visualize blood flow, but the preferred method is mesenteric duplex ultrasonography.
On light microscopy, chronic mesenteric ischemia features intestinal mucosal atrophy and loss of villi, along with atherosclerotic changes in the intestinal blood vessels.
On the other hand, colonic ischemia is usually caused by systemic hypotension and it typically affects the elderly population.
It can occur in any part of the colon, but the most prone parts are splenic flexure and distal sigmoid colon. This is because these regions are “watershed areas” meaning they are found between regions supplied by major arteries and generally have a limited blood supply.
This makes them more susceptible when the person is hypotensive or if there’s an underlying arterial insufficiency. Now, acute colonic ischemia causes mild crampy left-sided abdominal pain, hematochezia, and diarrhea and it’s most commonly result of thromboembolism.
On the other hand, chronic colonic ischemia is associated with abdominal pain that’s usually unrelated to meals, bloody diarrhea, and unintentional weight loss.
On plain abdominal radiographs and barium enema, the thumbprinting sign can sometimes be seen. This is the thickening of the colonic walls at irregular intervals and it’s thought to be due to edema.

Hemorrhoids11:42–13:02

Finally, let’s talk about hemorrhoids. These are normal tissue that form cushions within the rectum and anal canal.
These cushions are made of connective tissue, smooth muscle, and the blood filled arteriovenous plexus. When we say someone “has hemorrhoids,” we actually mean the veins in the hemorrhoids are dilated or distended, often causing them to form protruding masses.
Internal hemorrhoids are located above the pectinate line, which divides the upper two thirds and lower third of the anal canal.
On the other hand, external hemorrhoids are located below the pectinate line. Internal hemorrhoids usually bleed but don’t hurt, because they receive visceral innervation; whereas external hemorrhoids are painful because they receive somatic innervation from the inferior rectal branch of the pudendal nerve.
The diagnosis of hemorrhoids is typically done by inspection and digital rectal exam. As far as treatment goes, pramoxine, which is a local anesthetic, can be used for analgesia and antipruritic effects for hemorrhoids, but also burns, minor cuts, scrapes, and minor skin irritation.
With internal hemorrhoids that persistently bleed, rubber band ligation can be done; and external hemorrhoids can be treated by hemorrhoidectomy, which is the surgical removal of hemorrhoids.All right, as a quick recap.

Review13:02–14:11

Upper GI bleeding arises above the ligament of Treitz, and it includes bleeding from the esophagus, stomach, or duodenum.
A typical presentation of upper GI bleeding includes hematemesis, ‘coffee ground’ vomitus, and melena. Common causes of upper GI bleeding include esophageal varices, esophageal perforation, Mallory-Weiss syndrome, gastritis, peptic ulcers, gastric cancer, and Dieulafoy lesions.
On the other hand, lower GI bleeding arises below the ligament of Treitz, and it includes bleeding from the small intestine past the ligament of Treitz, large intestine, rectum, and anus.
A typical presentation of lower GI bleeding includes hematochezia. Common causes of lower GI bleeding include inflammatory bowel disease, diverticulosis, colorectal cancer, intestinal angiodysplasia, intestinal ischemia, and hemorrhoids.
Finally, since individuals with GI bleeding are losing blood they can become hemodynamically unstable or develop anemia.

Summary14:11–15:01

Now let’s go back to our cases. Joseph presented with painful hematemesis which began after a particularly intense night of vomiting and retching.
Painful hematemesis, retching, vomiting, and alcoholism are all specific for Mallory-Weiss syndrome! Therefore, you can order an endoscopy that will reveal the tears.
On the other hand, Lance complained about blood in his stool for the past 2 weeks and he also mentioned a marble-sized, soft mass at the anus that can be pushed back into the anal canal.
This is a classic description of a hemorrhoid and since he didn’t have pain as a symptom, it’s most likely an internal hemorrhoid.
In this case, a digital rectal exam should be done
Gastrointestinal bleeding: Pathology Review: Video | Osmosis