What is the diagnosis of Acute Diverticulitis?

From the Guidelines

Diagnosis of acute diverticulitis should begin with a thorough history and physical examination, followed by a contrast-enhanced CT scan of the abdomen and pelvis, as it is the gold standard imaging modality with high sensitivity and specificity, as recommended by the American College of Physicians in 2022 1. The diagnosis of acute diverticulitis typically involves a combination of clinical evaluation, laboratory tests, and imaging studies.

• A thorough history and physical examination should focus on symptoms such as left lower quadrant abdominal pain, fever, altered bowel habits, and nausea.
• Laboratory tests should include a complete blood count to check for leukocytosis (elevated white blood cell count), C-reactive protein, and basic metabolic panel.
• Urinalysis may help exclude urinary tract pathology. The gold standard imaging modality is a contrast-enhanced CT scan of the abdomen and pelvis, which can identify diverticular inflammation, abscess formation, perforation, or other complications with high sensitivity and specificity, as shown in a study published in the Annals of Internal Medicine in 2022 1.
• Ultrasound may be used as an initial imaging tool, particularly in young patients or pregnant women to avoid radiation exposure, though it is less sensitive than CT.
• Colonoscopy is generally avoided during acute episodes due to the risk of perforation but may be recommended 6-8 weeks after resolution to exclude other pathologies like colorectal cancer.
• The diagnosis is confirmed when imaging shows inflamed diverticula with surrounding fat stranding, wall thickening, or complications such as abscess or fistula formation. Early and accurate diagnosis is crucial for appropriate management and to prevent complications of diverticulitis, as highlighted in a study published in Gastroenterology in 2021 1.
• The American College of Physicians recommends the use of abdominal CT imaging when there is diagnostic uncertainty in a patient with suspected acute left-sided colonic diverticulitis, as stated in their guideline published in 2022 1.
• The guideline also suggests that clinicians manage most patients with acute uncomplicated left-sided colonic diverticulitis in an outpatient setting, and initially manage select patients with acute uncomplicated left-sided colonic diverticulitis without antibiotics.

From the Research

Diagnosis of Acute Diverticulitis

• Acute diverticulitis is a frequent and important diagnosis in gastrointestinal disease, most commonly involving the colon 2.
• The clinical diagnosis is often difficult to make, and several radiological studies have been used to assist in the diagnosis of acute diverticulitis, including barium enema, ultrasound, and computed tomography (CT) 2.
• CT is the preferable initial examination because of its ability to demonstrate not only the extent of intramural inflammation but also the degree of pericolic disease, including intraperitoneal inflammation, perforation, and abscess formation 2, 3, 4, 5, 6.

Imaging Features

• CT is a highly sensitive and specific modality for the diagnosis of acute diverticulitis and its complications, as well as for the exclusion of alternate causes of pathology 4.
• Ultrasound, MRI, and virtual CT colonoscopy have important adjunct roles for screening and workup of complications in specific patient populations 4.
• Imaging features that may help to differentiate diverticulitis from colonic malignancy include localized inflammation surrounding a diverticulum, wall thickening, and phlegmonous change 4.

Laboratory Studies and Treatment

• Initial laboratory studies include a complete blood count, basic metabolic panel, urinalysis, and measurement of C-reactive protein 3, 5.
• Treatment decisions are based on the categorization of disease as complicated vs. uncomplicated, with selected patients with uncomplicated diverticulitis potentially being treated without antibiotics 3, 5.
• Complicated diverticulitis is treated in the hospital with modified diet or bowel rest, antibiotics, and pain control, with abscesses that are 3 cm or larger being treated with percutaneous drainage 3, 5.