What is the best workspace for someone with right flank pain?

Best Imaging Workup for Right Flank Pain

For patients presenting with right flank pain, non-contrast CT of the abdomen and pelvis is the recommended first-line imaging study due to its superior sensitivity (95-100%) and specificity (94%) for detecting urinary stones and other causes of flank pain. 1, 2

Diagnostic Algorithm for Right Flank Pain

Initial Evaluation

• Non-contrast CT abdomen and pelvis:
  • Gold standard for detecting urolithiasis with sensitivity of 97-100% 1, 2
  • Can identify extraurinary causes of flank pain in approximately one-third of patients 3
  • Does not require contrast agent, reducing risk of contrast reactions
  • Can be completed within 5 minutes 3
  • Allows precise determination of stone size and location, which are critical factors for management decisions 4

When to Consider Alternative Imaging

1. Ultrasound with Color Doppler:

   • Consider in pregnant patients, children, or those with contraindications to radiation
   • Addition of color Doppler and twinkling artifact assessment improves sensitivity for small renal stones (up to 99% for stones <5mm) 1
   • Can be combined with radiography to improve stone detection (sensitivity 79-90%) 1
   • Less sensitive than CT but can identify hydronephrosis, which is present in most symptomatic stone cases 1

2. CT with IV contrast:

   • Consider when infection or alternative diagnoses are suspected
   • Helps differentiate ureteral stones from phleboliths or vascular calcifications 1
   • Can detect complications such as pyonephrosis, perinephric abscess, or urinoma 1
   • Provides additional diagnostic information in 5-18% of cases after non-contrast CT 1

3. CT Urography (CTU):

   • Consider when neither stone nor infection explains symptoms
   • Better confirms degree of obstruction and can aid in diagnosing radiolucent stones 1
   • Useful for comprehensive evaluation of the upper urinary tract 2

Clinical Pearls and Pitfalls

Important Considerations

• Moderate to severe hydronephrosis on ultrasound in patients with suspected urolithiasis is highly predictive of stone presence 1
• Patients with right flank pain may have conditions other than urolithiasis, including:
  • Right colonic diverticulitis (8% of RLQ pain cases) 1
  • Bowel obstruction (3% of RLQ pain cases) 1
  • Infectious enterocolitis, typhlitis, or inflammatory terminal ileitis 1
  • Page kidney (subcapsular hematoma causing secondary hypertension) 5
  • Lateral Cutaneous Nerve Entrapment Syndrome (LACNES) 6
  • Abdominal aortic aneurysm (must be ruled out as life-threatening) 7

Common Pitfalls

• Anchoring on kidney stones when evaluating flank pain and missing other diagnoses 5
• Relying solely on ultrasound, which may miss stones and other pathologies
• Overuse of contrast when not indicated, exposing patients to unnecessary risks
• Failure to consider neuropathic causes of flank pain such as LACNES 6

Follow-up Considerations

• For patients with identified stones <5mm in the distal ureter, spontaneous passage is likely 2
• If infection is identified with obstruction, urgent decompression may be needed 2
• Patients with persistent hematuria require continued surveillance even after initial negative evaluation 2
• Consider stratified care approach for ongoing pain management 1

By following this evidence-based approach to imaging for right flank pain, clinicians can efficiently diagnose the cause and initiate appropriate treatment, minimizing morbidity and improving patient outcomes.