Diverticular disease: Clinical practice

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Diverticular disease: Clinical practice

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A 62-year-old man comes to the primary care clinic because of pain in his lower left abdominal quadrant, painless hematochezia, and constipation for the past few weeks. Medical history shows that he has suffered a myocardial infarction two years ago and has been taking aspirin daily since. His doctor orders a colonoscopy and notices small sacs bulging out around the large intestine. Which of the following is the most likely explanation for this patient’s physical findings?

Transcript

Content Reviewers:

Rishi Desai, MD, MPH

Diverticula are small outpouchings that form along the walls of a hollow structure.

In the context of the large intestine, they’re called colonic diverticula, but they can form in the small intestine, as well as other spots like along the esophagus.

Diverticula usually form at weak spots along the wall, like where a blood vessel penetrates the muscle layer of the intestine.

Now there are two types of diverticula. The first is a true diverticula which is a herniation that involves all layers of the intestinal wall - like a Meckel’s diverticulum.

The second is a false or pseudodiverticula which is where only the mucosa and submucosa slide through the intestinal wall, and these end up being more common.

Risk factors for diverticula, including eating a high-fat, red meat diet that’s low in fiber.

Diverticulosis is the presence of diverticula and when there’s colonic diverticula, typically these happen in the left and sigmoid colon- the rectum is usually spared.

Sometimes it’s asymptomatic, and diverticulosis is diagnosed incidentally during an abdominal scan or a colonoscopy that was needed for another reason.

When diverticulosis is symptomatic, it’s called diverticular disease.

Typically diverticular disease causes some abdominal pain and a CT-scan usually shows some bowel thickening. But at this stage, treatment is mainly encouraging a high-fiber diet with grains and vegetables.

But at any point diverticulosis can cause complications.

One complication is bleeding due to weakening and breaking of blood vessels near a diverticula.

Mild bleeding can cause painless hematochezia, but severe bleeding can lead to hypovolemic shock.

When there’s bleeding, depending on the severity, lab work and resuscitation are usually done.

Labs include a CBC to look for signs of anemia and assess the platelet count.

If there are signs of hypovolemia, intravenous fluids are given.

To see if the bleeding is coming from the upper GI tract, gastric lavage- which is where fluids are placed in the stomach and then suctioned back out to look for signs of bleeding - and an upper endoscopy can be done as well.

After that, a colonoscopy is performed within 24 hours of presentation to identify and stop the source of the bleeding using endoscopic therapy.

One option is to inject the site of bleeding with epinephrine.

Alternatively, the vessel can be treated with thermocoagulation using cautery probes.

Cautery probes use an electrical current to melt a tiny blood vessel and seal it shut to stop the bleeding.

If the source of bleeding isn’t identified using colonoscopy or if the bleeding can’t be stopped endoscopically, then angiography can be used. That’s where a contrast agent is injected into a blood vessel and then imaging is done to identify the location of any active bleeding. Unfortunately, it may miss intermittent bleeds.

Now, if a source of active bleeding is found through angiography, then vasoconstricting medication like vasopressin can be given, or the bleeding vessel can be embolized.

In embolization, the bleeding vessel is mechanically blocked using coils or polyvinyl alcohol particles that are delivered through a catheter.

If neither colonoscopy nor angiography are able to identify and stop the bleeding, then surgery is required and often a segmental colectomy is done. That’s where part of the colon is removed.

Another complication of diverticulosis is acute diverticulitis - which is an infection of the diverticula.

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 wall of the diverticula.

Symptoms include left lower quadrant abdominal pain and fever, along with a change in bowel habits, like alternating constipation and diarrhea.

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, but usually with an abscess, the oral antibiotics used for acute diverticulitis don’t work as well, and the fever and other symptoms persist.

If the inflamed diverticula is near another organ or skin surface it can also create a fistula, and this most commonly occurs with the bladder. When that happens it’s called a colovesical fistula.

In a colovesical fistula there can be dysuria, pneumaturia -which is the passage of gas in the urine, as well as fecaluria- which is the passing of stool in the urine. Yep, it’s pretty hard to forget that set of symptoms!

Acute diverticulitis can also lead to a partial obstruction of the colon due to the inflammation, and that can cause abdominal pain, distention, and vomiting.

Finally, an inflamed diverticula can perforate and cause peritonitis. Clinically that can result in a tender, distended abdomen with guarding and rigidity.

The lab work for acute diverticulitis and its complications include a CBC, looking for leukocytosis, along with electrolytes- especially if there’s dehydration due to diarrhea- and urine analysis, which can show sterile pyuria due to inflammation near the bladder.

If there’s acute abdominal pain, then an AST and ALT, alkaline phosphatase, bilirubin, amylase, and lipase can help rule out other potential causes like acute pancreatitis or cholecystitis.

If the individual has ongoing diarrhea, then stool cultures for Salmonella, Shigella, Yersinia, Campylobacter, and E.coli can be sent.

In addition, stool microscopy to search for ova and parasites along with testing for C.difficile toxin are done if those are suspected.

Acute diverticulitis is usually diagnosed with a CT scan with contrast of the abdomen and pelvis, which will show colonic diverticula, with localized bowel wall thickening, and increased density in the surrounding fat.

The CT can also identify the presence of an abscess or fistula.

If there’s an abscess, there will be a fluid collection surrounded by an inflamed diverticula.

A fistula will show the diverticula and local colonic thickening near a thickened bladder and may also show air collections in viscera other than the bowel.

If there’s a partial bowel obstruction, then imaging shows dilated intestinal loops with air-fluid levels.

In individuals with perforation and peritonitis, the CT shows free air seen within the peritoneum.

A colonoscopy should not be performed in acute diverticulitis, because it increases the risk for perforation and subsequent peritonitis.

Treatment of acute diverticulitis can differ based on the presence of complications.

If there’s uncomplicated acute diverticulitis, it can be treated with 7 to 10 days of oral antibiotics that treat gram-negatives like Escherichia coli and anaerobes like Bacteroides fragilis.

Common regimens are Metronidazole plus either Ciprofloxacin or Levofloxacin or Trimethoprim-Sulfamethoxazole.

In individuals that are allergic to Metronidazole, Moxifloxacin alone can be used instead.

If the individual is severely ill, then IV Metronidazole plus either IV Cefuroxime or IV Ciprofloxacin are used instead, along with IV fluids and pain medications like Ketorolac.