Diverticular disease: Pathology review

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Case study 0:00–1:17

At the gastroenterology clinic, there is a 62- year- old male from Germany, named Karl, who came in for his regular colonoscopy.
He is totally asymptomatic, except for occasional vague abdominal discomfort after meals. Next, a 65- year- old Native American named James came to the emergency department after two episodes of painlessly passing fresh, red blood in his stool.
Finally, Zendaya, a 78- year- old African- American female, was brought to the hospital from a nursing home by paramedics, due to a severe pain in the left lower abdomen which started this morning.
Her temperature was measured at 101.8°F or 38.8°C at the nursing home. On further history, they all had diets low in fiber and high in fat and red meat and suffered from chronic constipation.
Zendaya’s nursing home attendant reports that lately her constipation has been even worse than usual; in fact, her last bowel movement was more than three days ago.
Karl, James and Zendaya all have diverticula in the colon. Diverticula are small outpouchings that form along the walls of a hollow structure, most commonly, the large intestine.

Pathology1:17–2:44

According to their pathogenesis, diverticula can be broadly grouped into traction and pulsion diverticula. Traction diverticula occur due to the pulling forces of an adjacent inflammatory site, resulting in scarring and outpouching of all layers of the intestinal wall.
These are also known as true diverticula. Next, there’s pulsion diverticula, which are a result of high pressures created during a strained bowel movement.
The pressure pushes on the mucosa and submucosa until they bubble out through weak spots along the wall, like where a blood vessel penetrates the muscle layer of the intestine.
These are also known as false or pseudodiverticula since they don’t involve all layers of the intestinal wall. For your exams, it’s important to know that, most of the time, diverticula in the large intestine, and particularly, the left and sigmoid colon, are pulsion or false diverticula.

Diverticulosis2:44–3:40

Having diverticula in the colon is called diverticulosis, and it’s more common in individuals older than 60 years old, consuming a diet low in fiber and high in fatty foods, like red meat.
Fiber helps stool move more easily through the colon, so diets low in fiber can lead to constipation which means more force is required to move bulky, hard stool.
Most of the time, people won’t even know they have diverticulosis because they don’t have any symptoms besides constipation and mild or vague abdominal discomfort after meals.
Diagnosis is typically made incidentally during a colonoscopy or CT scan that might be done for another reason entirely.
Okay, so even though diverticulosis doesn’t cause major distress in the person, they can still cause serious complications.

GI Bleeding3:40–4:22

One complication is bleeding due to weakening and breaking of blood vessels near a diverticula. It’s important to know that diverticulosis is the most common cause of acute lower gastrointestinal bleeding.
This will typically appear in your exam as an elderly patient with a history of chronic constipation and painless hematochezia, which means bright red or maroon blood passing from the rectum.
Remember, bright red blood usually means lower GI bleed, and painful hematochezia usually indicates hemorrhoids. Now, another complication of diverticulosis is acute diverticulitis, which is an infection of the diverticula.

Acute Diverticulitis4:22–6:56

Typically it starts when there’s increased pressure in the lumen of the intestines or food impaction in the diverticulum that leads to micro-perforations in the diverticula.
The bacteria in the lumen of the gut dive into these microperforations, and cause infection within the intestinal wall. Symptoms include left lower quadrant abdominal pain and low- grade fever, along with a change in bowel habits, like alternating constipation and diarrhea.
And treatment is with antibiotics. Acute diverticulitis can also lead to the formation of an abscess within the inflamed diverticula.
The symptoms of a diverticular abscess are about the same as the symptoms of acute diverticulitis, the clue for abscess is that the oral antibiotics are ineffective so the symptoms persist.
In some cases, inflammation leads to a partial obstruction of the colon, and that can cause abdominal distention, nausea, and vomiting.
In other cases, if the diverticula become distended enough, it may rupture and cause peritonitis, resulting in a tender, distended abdomen with guarding and rigidity.
Alternatively, it can create a fistula, which is a connection with an adjacent organ or structure. Since it sits pretty close to the bladder, a fistula connecting the large intestine to the bladder may form, called a colovesicular fistula, and this might result in dysuria, pneumaturia, or passage of gas in the urine, as well as fecaluria, or stool in the urine.
Diagnosis of acute diverticulitis and its complications is usually made with a CT with contrast of the abdomen and pelvis.
A key concept that is frequently tested is that colonoscopy is contraindicated in acute diverticulitis, because it increases the risk for perforation and subsequent peritonitis.
Okay, to review! Diverticula are abnormal outpouchings from the colonic lumen and can be classified into traction or true diverticula, which involve all layers of the intestinal wall and pulsion or false diverticula, which is where only the mucosa and submucosa slide through the intestinal wall, are usually located in the left and sigmoid colon- and these end up being more common.

Review6:56–8:15

The presence of diverticula is known as diverticulosis and risk factors include advanced age, chronic constipation, and low-fiber, high-fat diet.
Diverticulosis is typically asymptomatic but can present with vague abdominal discomfort after meals. Complications include diverticular bleeding, presenting as painless rectal bleeding and diverticulitis.
Also acute diverticulitis, presenting as left lower quadrant pain with fever. Sometimes, acute diverticulitis can lead to abscess, fistula, partial colonic obstruction and perforation with peritonitis.
Now, back to the patients! All three of them have the risk factors for diverticulosis including old age, constipation and low-fiber, high-fat diet.

Summary8:15–9:08

Karl had vague abdominal discomfort after meals and diverticulosis was discovered incidentally during his colonoscopy. Meanwhile, James probably has diverticulosis with bleeding as a complication.
This can be confirmed with a CT scan or colonoscopy. And Zendaya has the typical presentation of acute diverticulitis, with acute left lower abdominal pain and fever.
The fact that she hasn’t passed stool for more than 3 days might be a clue to partial colonic obstruction. Diagnosis can be made with a CT, but a colonoscopy is contraindicated.
Diverticular disease: Pathology Review: Video | Osmosis