From the Guidelines
The decision to order a CT abdomen and pelvis with or without contrast should be based on the clinical indication, with contrast-enhanced CT being the preferred choice for most abdominal and pelvic pathologies, as it provides better tissue differentiation and vascular visualization, as suggested by the American College of Radiology appropriateness criteria 1. When evaluating for infection, inflammation, malignancy, vascular abnormalities, or active bleeding, contrast-enhanced CT is the preferred choice. Non-contrast CT is appropriate for kidney stones, urinary calculi, some follow-up studies, and in patients with contraindications to contrast, such as severe renal impairment (eGFR <30 mL/min/1.73m²), previous severe contrast reaction, or pregnancy 1. Some key points to consider when deciding between contrast-enhanced and non-contrast CT include:
- Clinical indication: What is the suspected diagnosis or pathology?
- Patient factors: Renal function, allergies, pregnancy status
- Contraindications to contrast: Severe renal impairment, previous severe contrast reaction, pregnancy
- Alternative imaging options: Ultrasound, MRI, or other modalities may be suitable alternatives in certain cases The use of IV contrast increases the spectrum of detectable pathology in patients with nonlocalized pain, and CT with IV contrast adds diagnostic value and helps direct management, as shown in a prospective study assessing the impact of CT on management decisions in the ED 1. In summary, the choice between contrast-enhanced and non-contrast CT abdomen and pelvis depends on the clinical context and the suspected diagnosis, with contrast-enhanced CT being the preferred choice for most abdominal and pelvic pathologies. Contrast-enhanced CT should be used when evaluating for infection, inflammation, malignancy, vascular abnormalities, or active bleeding, while non-contrast CT is suitable for kidney stones, urinary calculi, and patients with contraindications to contrast 1.
From the Research
Decision to Order CT Abdomen and Pelvis with or without Contrast
To determine whether to order a CT abdomen and pelvis with or without contrast, several factors should be considered:
- Patient's renal function: Non-contrast CT scans are recommended for patients with limited renal function 2
- Allergy to iodinated contrast: Non-contrast CT scans are recommended for patients with an allergy to iodinated contrast 2
- Suspected renal calculus, retroperitoneal hematoma, common duct calculus, abdominal aortic aneurysm with or without rupture: Non-contrast CT scans are recommended for these conditions 2
- PET-CT scan: Non-contrast CT scans are recommended for patients undergoing a PET-CT scan 2
Benefits of Contrast-Enhanced CT
- Increased detection of urgent findings: Administration of IV contrast for the first CT AP was associated with increased detection of urgent findings compared with non-contrast CT 3
- Better characterization of urgent and non-urgent findings: Contrast-enhanced CT AP following an initial non-contrast CT AP examination better characterized both urgent and non-urgent findings 3
Alternative Imaging Options
- Oral contrast: The use of oral contrast is more variable, and its use depends on the specific indication and patient factors 4, 5, 6
- Rectal contrast: Rectal contrast is rarely used 5
Clinical Practice Variations
- Contrast practices for abdominal/pelvic CT vary nationally, according to a survey of US academic EDs 5
- For multiple indications, the contrast practices of a substantial number of respondents deviated from those recommendations given the highest clinical appropriateness rating by the American College of Radiology 5
Key Considerations
- Adherence to ACR appropriateness criteria for IV contrast administration was associated with increased detection of urgent pathology on the first CT 3
- Encouraging urgent care physicians to preferentially order IV contrast-enhanced CT AP examinations in adherence with ACR appropriateness criteria may increase detection of urgent pathology and avoid short-term repeat CT AP 3