From the Guidelines
For patients presenting with acute nonlocalized abdominal pain, a CT scan with intravenous contrast is the recommended initial imaging choice, as it provides the most comprehensive evaluation of potential pathologies, including pneumonia, hepatobiliary disease, and gastrointestinal issues, as outlined in the ACR Appropriateness Criteria 1. When evaluating abdominal pain, it is essential to consider the broad range of potential pathologies, including infections, inflammations, and tumors, which can be better visualized with contrast-enhanced CT scans.
- The use of intravenous contrast enhances the detection of vascular structures, inflammation, and tumors, making it superior for identifying most abdominal pathologies.
- However, non-contrast CT may be appropriate for patients with kidney dysfunction (eGFR <30 mL/min), contrast allergy, or when specifically evaluating for urinary stones, calcifications, or foreign bodies, as noted in the study by 1.
- For suspected bowel obstruction or perforation, oral contrast may be added, although many centers now perform these studies without oral contrast to expedite diagnosis, as discussed in the context of abdominopelvic CT scans 1.
- If the clinical concern involves the biliary system, pancreas, or liver, a three-phase CT (non-contrast, arterial, and venous phases) might be necessary, highlighting the importance of tailored imaging approaches based on clinical suspicion.
- Patients should fast for 4-6 hours before the scan if oral contrast is planned, and the radiation dose from a standard abdominal CT, approximately 10 mSv, should be considered when imaging younger patients or those requiring multiple studies, as mentioned in the guidelines 1.
- Alternative imaging modalities like ultrasound or MRI may be considered for pregnant patients or those requiring repeated imaging, underscoring the need for individualized approaches based on patient-specific factors and clinical context.
From the Research
Abdominal Pain CT with or without Contrast
- The use of oral contrast in abdominal CT scans for patients with acute nontraumatic abdominal pain has been debated in several studies 2, 3, 4.
- A study published in 2017 found that oral contrast is noncontributory to radiological diagnosis in most patients presenting to the emergency department with acute nontraumatic abdominal pain, and that these patients can undergo abdominal CT scanning without oral contrast with no effect on radiological diagnostic performance 2.
- Another study published in 2016 supported the idea of performing CT scans of the abdomen and pelvis without the need for positive oral contrast in adult patient populations with acute abdominal and pelvic pain, citing increased patient throughput, patient preference, patient safety, and retention of high diagnostic accuracy as reasons for this change in practice 3.
- A study published in 2015 evaluated the use of computed tomography without oral contrast in patients with body mass index greater than 25 and found that CT examinations can be acquired without oral contrast without compromising the clinical efficacy of CT 4.
- The use of contrast-enhanced CT scanning has been shown to result in superior diagnostic precision in patients with acute abdominal pain, with a correct diagnosis rate of 96.8% in one study 5.
- Alternative contrast media, such as carbon dioxide, gadolinium, and dilute iodinated contrast material, may be used in patients with renal disease or contrast allergy, but each has its own unique features and limitations 6.
Key Findings
- Oral contrast is not necessary for most patients with acute nontraumatic abdominal pain undergoing abdominal CT scans 2, 3, 4.
- Contrast-enhanced CT scanning is highly accurate in diagnosing acute abdominal pain, with a correct diagnosis rate of 96.8% in one study 5.
- Alternative contrast media may be used in patients with renal disease or contrast allergy, but their use is limited by their unique features and limitations 6.