Ultrasound for Diagnosing Diverticulitis

Diagnostic Accuracy

Ultrasound demonstrates sensitivity of >90% and positive predictive value of >90% in meta-analyses and prospective studies for diagnosing diverticulitis, though accuracy is modestly less than CT 1
Acute diverticulitis can be diagnosed by US using three key criteria: short-segment colonic wall thickening, inflamed diverticulum, and noncompressible hyperechoic pericolic tissue 1, 3

US accuracy is particularly diminished in obese patients and for distal sigmoid diverticulitis 1, 3
US requires a higher level of operator expertise than CT, with estimates suggesting a minimum of 500 examinations required for competency 1
US is less likely to identify alternative diagnoses compared to CT 1, 3

The Infectious Diseases Society of America (IDSA) suggests CT as the initial diagnostic modality for non-pregnant adults with suspected acute diverticulitis (conditional recommendation, very low certainty of evidence) 2, 4
The American College of Radiology (ACR) acknowledges that while US is the initial imaging test for suspected diverticulitis in some European countries, it is not widely used in the United States, partly due to a larger obese population 1, 3

Non-invasive with no radiation exposure 1, 3
If used as initial imaging, US may reduce the number of CT scans performed without negative effect on patient care 1

Consider US as first-line imaging in patients with contraindications to CT, pregnant patients, and young patients with typical presentation to minimize radiation exposure 1, 2, 4, 5
Proceed to CT if US is inconclusive or negative despite high clinical suspicion, or if complicated diverticulitis is suspected 1, 3

Relying solely on US may miss complicated diverticulitis, and operator dependence is a significant limitation; diagnostic accuracy varies with sonographer experience 1
US has lower specificity than CT and is less likely to identify alternative diagnoses that may mimic diverticulitis 1, 3