Diverticulitis is a form of diverticular disease that happens when diverticula, small pouches in the wall of the large intestine (colon), push through weak spots in the colon’s outer muscle layers. Inflammation of these diverticula are called diverticulitis.
In the past, doctors often recommended people who had diverticulitis avoid foods such as nuts, popcorn, and seeds because it was thought these particles could enter or block the diverticula.
More recent research indicates these foods are not harmful and since they are high in fiber, they may help some patients. Each patient is different and some people may find certain foods aggravate or trigger diverticulitis symptoms.
Some foods such as those low in fiber or high in sugar that may increase the risk of developing diverticulitis or trigger diverticulitis symptoms include:
- Red meats
- Processed meats
- Fried foods
- Full fat dairy products
A high-fiber diet including foods such as foods fruits and vegetables, whole grains, and dried beans and lentils is usually recommended for patients with diverticulitis.
What Are Symptoms of Diverticulitis?
Symptoms of diverticulitis include:
- Abdominal pain (most commonly in the left lower quadrant)
- Nausea
- Vomiting
- Constipation (may be severe)
- Fever
- Gas (flatulence)
- Bloating
What Causes Diverticulitis?
In Western countries, the diverticulitis is believed to be caused by the classic Western high-fat and low-fiber diet.
Diverticulitis may also be caused by increased pressure from constipation or increasing abdominal girth in obesity.
How Is Diverticulitis Diagnosed?
Diverticulitis is diagnosed based on a medical history and physical examination.
Laboratory tests that may be indicated include:
- Blood tests
- Blood cultures
- Electrolyte assays
- Hemoglobin level
- Liver enzyme and lipase levels
- Renal function tests
- White blood cell count
- Urine tests
- Urinalysis
- Urine culture
- Stool test for blood
- A pregnancy test for females of childbearing age with abdominal pain
- Imaging
What Is the Treatment for Diverticulitis?
Treatment for diverticulitis depends on the severity, any complications, and other underlying medical conditions.
An uncomplicated, mild diverticulitis attack may go away without treatment, but it is important to see a doctor to assess the severity and determine if treatment is needed.
Treatment for mild diverticulitis includes:
- Clear liquid diet for 2-3 days; progress to a soft diet as tolerated
- 7-10 days of oral broad-spectrum antibiotics if needed, such as:
- Ciprofloxacin (Cipro) plus metronidazole (Flagyl)
- Trimethoprim-sulfamethoxazole (Bactrim) plus metronidazole (Flagyl)
- Amoxicillin-clavulanate (Augmentin)
- Moxifloxacin (Avelox)
- Acetaminophen (Tylenol) and antispasmodics for pain
In more severe cases, hospitalization may be needed. If hospitalized, treatment may include:
- Clear liquid diet; progress to a soft diet as tolerated
- Intravenous (IV) or oral antibiotics
- Beta-lactamase-inhibiting antibiotics such as piperacillin/tazobactam (Tazocin) and ticarcillin/clavulanic acid (Timentin)
- Carbapenems such as ertapenem (Invanz)
- Abscesses less than 3 cm: Typically resolved with antibiotics
- Abscesses greater than 4 cm: Drain percutaneously
- Pain management
- Morphine is preferred, though it may affect bowel tone and sphincters
- Acetaminophen and antispasmodics such as dicyclomine are first-line medications used to manage pain and cramping in mild to moderate disease
- Elective surgical resection
From 
https://www.niddk.nih.gov/health-information/digestive-diseases/diverticulosis-diverticulitis/eating-diet-nutrition