Does a CT (Computed Tomography) abdomen to check for Left Lower Quadrant (LLQ) pain require contrast?

CT Abdomen with IV Contrast is Recommended for Evaluating LLQ Pain

CT abdomen and pelvis with IV contrast is the preferred imaging modality for evaluating left lower quadrant (LLQ) pain, particularly when diverticulitis is suspected. 1

Imaging Recommendations Based on Clinical Scenario

First-line Imaging:

• CT abdomen and pelvis with IV contrast is rated highest (8/9) by the American College of Radiology (ACR) Appropriateness Criteria for evaluating LLQ pain, especially when diverticulitis is suspected 1
• IV contrast improves characterization and detection of bowel wall pathology, pericolic abnormalities, vascular pathology, and intra-abdominal fluid collections 1
• CT with IV contrast has reported sensitivity and specificity as high as 100% in diagnosing sigmoid diverticulitis 1

Alternative Options:

• CT abdomen and pelvis without contrast is considered "may be appropriate" (6/9) by ACR when IV contrast is contraindicated 1
• Unenhanced CT can be accurate in assessing nonspecific acute abdominal pain in emergency settings, particularly in elderly patients 1
• Ultrasonography may be considered as an alternative in specific populations (e.g., pregnant patients, women of reproductive age) 2

Benefits of CT with IV Contrast

• Provides comprehensive evaluation of all abdominal organs in a single examination 2
• Detects complications such as abscess, fistula, obstruction, and perforation 2
• Identifies alternative diagnoses that present with similar clinical symptoms 1
• Improves diagnostic certainty from 70.5% to 92.2% in emergency department settings 2
• Guides appropriate treatment planning by determining disease severity 1

Role of Oral Contrast

• Administration of oral contrast may be helpful for bowel luminal visualization but is not essential 1
• Recent evidence suggests oral contrast is noncontributory to radiological diagnosis in most patients presenting with acute nontraumatic abdominal pain 3
• Eliminating oral contrast reduces time to diagnosis without compromising diagnostic accuracy 3

Clinical Considerations

• For women of reproductive age, consider gynecologic causes of LLQ pain and obtain pregnancy testing before ordering CT 2
• In pregnant patients, ultrasonography and MRI are preferred over CT to avoid radiation exposure 2
• CT should be used judiciously in female patients of childbearing age in whom gynecologic etiologies have been clinically or sonographically excluded 1

Common Pitfalls to Avoid

• Relying solely on conventional radiography for diagnosis of LLQ pain, as it has limited diagnostic value 2
• Using contrast enema as initial imaging, which has been supplanted by CT due to its inability to show extraluminal abnormalities 1
• Failing to consider alternative diagnoses that can mimic diverticulitis, which CT can help identify 1

In summary, while CT without contrast may be adequate in some cases, the evidence strongly supports the use of IV contrast-enhanced CT as the optimal imaging modality for evaluating LLQ pain to maximize diagnostic accuracy and guide appropriate treatment.