From the Guidelines
A CT scan should be obtained in patients with suspected diverticulitis who have severe symptoms, signs of complications, or diagnostic uncertainty, as it is the most useful examination for confirming the diagnosis, assessing disease severity, and detecting complications. According to the American College of Radiology Appropriateness Criteria 1, CT is recommended for patients with fever, significant abdominal pain, elevated white blood cell count, or signs of peritonitis. It's also indicated when there are concerning features such as immunosuppression, advanced age, or lack of response to initial antibiotic therapy.
Some key points to consider when deciding to obtain a CT scan in diverticulitis include:
- The ability of CT to identify complications like abscess, perforation, fistula, or obstruction that may require surgical intervention or drainage procedures 1
- The use of IV and oral contrast material to improve diagnosis of abscess and distinguish from adjacent bowel 1
- The potential of CT to predict unfavorable outcomes from acute diverticulitis, such as longer hospitalization and need for surgery 1
- The ability of CT to differentiate contained extraluminal air from abscess from spilled feces, which is important for clinical management and surgical decision-making 1
In terms of the specific CT protocol, contrast-enhanced CT of the abdomen and pelvis is the preferred imaging modality due to its high sensitivity and specificity for diverticular disease 1. However, unenhanced CT or radiation dose-reduced contrast-enhanced CT may be used in patients with contraindications to IV contrast material or to reduce radiation exposure 1.
Overall, the decision to obtain a CT scan in diverticulitis should be based on the individual patient's clinical presentation and risk factors, with the goal of confirming the diagnosis, assessing disease severity, and guiding appropriate management decisions.
From the Research
Indications for CT Scan in Diverticulitis
- CT scan is necessary to diagnose the first occurrence of diverticulitis, as it provides radiological evidence of inflammation 2
- CT scan is also warranted when the severity of symptoms suggests that perforation or abscesses have occurred 2
- CT scan is used to classify diverticulitis as complicated or uncomplicated, which directs management 2
- Patients with suspected complicated diverticulitis, such as those with high C-reactive protein (CRP) levels, should undergo a CT scan to confirm the diagnosis and assess for complications 3, 4, 5
CT Scan in Relation to C-Reactive Protein (CRP) Levels
- A CRP cut-off value of 149.5 mg/l can significantly discriminate acute uncomplicated diverticulitis from complicated diverticulitis 3
- A CRP value over 150 mg/l is an independent risk factor for acute complicated diverticulitis 3
- CRP levels can be used to predict the severity of acute diverticulitis, with higher levels indicating a greater probability of surgical treatment or percutaneous intervention 4, 5
Timing of CT Scan
- CT scan should be performed at the time of diagnosis to assess for complications and direct management 2, 6
- CT scan may not be necessary for patients with uncomplicated diverticulitis who are afebrile and clinically stable 2
- CT scan should be considered 6 weeks after resolution of symptoms in patients with complicated diverticulitis who have not had a high-quality colonoscopy in the past year 6