From the Guidelines
Ultrasound of the abdomen can diagnose diverticulitis, but it is not the preferred first-line imaging test due to its limitations and the superior diagnostic accuracy of CT scans. The use of ultrasound for diagnosing diverticulitis has been supported by some studies, with a sensitivity and positive predictive value of >90% for graded compression US, as reported in the 2023 update of the ACR Appropriateness Criteria 1. However, its effectiveness is reduced by factors such as bowel gas, operator dependence, and difficulty in visualizing deep pelvic structures.
Some key points to consider when evaluating the use of ultrasound for diverticulitis diagnosis include:
- The accuracy of ultrasound is modestly less than that of CT, especially in obese patients and in patients with distal sigmoid diverticulitis 1.
- Ultrasound requires a higher level of training for the diagnosis of diverticulitis than does CT, with an estimated minimum of 500 examinations required for competency 1.
- CT scan with intravenous contrast is the gold standard for diagnosing diverticulitis, offering superior visualization of the entire abdomen and pelvis, better detection of complications, and more consistent results regardless of the operator 1.
- Ultrasound may be used in specific situations, such as for pregnant patients, young patients to avoid radiation exposure, or when CT is unavailable, but it should not be considered the primary diagnostic tool for suspected diverticulitis.
In terms of the diagnostic criteria for diverticulitis using ultrasound, the 2023 update of the ACR Appropriateness Criteria 1 lists the following:
- Short-segment colonic wall thickening (>5 mm)
- Inflamed diverticulum in the thickened area (hypoechoic and surrounded by hyperechoic fat)
- Noncompressible hyperechoic pericolic tissue
Overall, while ultrasound can be used to diagnose diverticulitis, its limitations and the superior diagnostic accuracy of CT scans make it a less preferred option for first-line imaging.
From the Research
Ultrasound Diagnosis of Diverticulitis
- Ultrasound (US) can be used to diagnose diverticulitis, but its accuracy varies depending on the complexity of the condition 2, 3, 4, 5, 6.
- A study published in 2021 found that clinical-sonographic assessment using US had optimal sensitivity (92.7%) and specificity (90.9%) for diverticulitis, but low sensitivity (50%) for complicated diverticulitis 2.
- Another study from 2012 noted that US is most useful in early, uncomplicated diverticulitis, and that daily repeated US examinations can show the predictable and benign course of the condition 3.
- However, US has limitations in diagnosing complicated diverticulitis, and computed tomography (CT) is often superior in such cases 3, 4, 5.
Comparison with Other Diagnostic Methods
- A 2014 study found that US misdiagnosed 17% of patients with uncomplicated diverticulitis and 79% with complicated diverticulitis, highlighting the need for CT scans to confirm diagnosis and exclude complications 4.
- A prospective analysis published in 2010 found that the accuracy of clinical diagnosis for colonic diverticulitis is low, and that US and CT have superior diagnostic accuracy, but rarely change the initial management proposal 5.
- A review of 208 patients published in 2003 found that US exhibited a sensitivity of 86% in cases subjected to surgery, and of 94% in the global patient population, and that US evidence of complicated diverticulitis was statistically predictive of surgical risk during the acute phase 6.
Clinical Implications
- The use of US in diagnosing diverticulitis can help select patients who need CT scans, reducing the need for unnecessary imaging 2.
- US can also be used to monitor the progression of diverticulitis and predict the risk of complications, particularly in younger patients [<50 years] 6.
- However, the limitations of US in diagnosing complicated diverticulitis highlight the need for careful clinical evaluation and the use of CT scans when necessary 3, 4, 5.