Should I order a CT abdomen pelvis with or without contrast for a patient with sudden excruciating right lower quadrant pain radiating to the back?

CT Abdomen and Pelvis with IV Contrast for Right Lower Quadrant Pain

For a patient with sudden excruciating right lower quadrant pain radiating to the back, CT abdomen and pelvis with IV contrast should be ordered as the initial imaging study of choice. 1

Rationale for CT with IV Contrast

CT with IV contrast provides superior diagnostic accuracy for evaluating right lower quadrant (RLQ) pain due to:

• High sensitivity (95-100%) and specificity (94-100%) for detecting appendicitis 1
• Ability to identify alternative diagnoses in 23-45% of patients 1
• Superior visualization of:
  • Bowel wall pathology
  • Pericolic abnormalities
  • Vascular pathology
  • Intraabdominal fluid collections 1

Advantages Over Non-Contrast CT

IV contrast significantly enhances diagnostic capabilities:

• Improves detection of urgent findings compared to non-contrast CT 1
• Provides better characterization of bowel wall inflammation and perfusion 1
• Allows better visualization of vascular structures that may be involved 1
• Helps distinguish between different causes of RLQ pain that may have similar appearances on non-contrast imaging 2

Diagnostic Yield for RLQ Pain

CT with IV contrast is excellent for evaluating RLQ pain because:

• It can detect appendicitis with high accuracy (sensitivity 95%, specificity 94%) 2
• It identifies alternative diagnoses such as:
  • Right colonic diverticulitis (8% of RLQ pain cases)
  • Bowel obstruction (3% of RLQ pain cases)
  • Benign adnexal masses
  • Inflammatory bowel disease
  • Infectious enterocolitis
  • Urinary stones 2, 1

Clinical Impact

Using CT with IV contrast:

• Changes physician diagnosis in 49-54% of cases 1
• Increases diagnostic certainty from 70.5% to 92.2% 1
• Reduces negative appendectomy rates from 25% to 1.7-7.7% 1
• Guides appropriate management decisions 2, 1

Common Pitfalls to Avoid

1. Don't delay imaging in a patient with classic appendicitis symptoms 1
2. Don't rely on absence of fever to rule out appendicitis (15.6% of confirmed cases present without fever) 1
3. Don't start antibiotics before confirming diagnosis as this may mask findings 1
4. Don't assume normal white blood cell count rules out appendicitis 1
5. Don't use ultrasound as first-line in this clinical scenario, especially if the patient is obese 1

Special Considerations

• If IV contrast is absolutely contraindicated (severe allergy, renal failure), non-contrast CT is an acceptable alternative 1
• For pregnant patients, ultrasound should be first-line, followed by MRI without contrast if ultrasound is non-diagnostic 1
• For young, thin adults, ultrasound may be considered initially to avoid radiation, but with awareness of its lower sensitivity 1

CT abdomen and pelvis with IV contrast is the optimal imaging choice for evaluating sudden excruciating right lower quadrant pain radiating to the back, as it provides the highest diagnostic accuracy and ability to identify the wide range of potential causes for this presentation.