ACR Appropriateness Criteria® Hydronephrosis on Prior Imaging-Unknown Cause

Area of Science:

• Radiology
• Medical Imaging
• Urology

Background:

• Hydronephrosis evaluation requires careful consideration of clinical context.
• Imaging choices vary significantly based on patient presentation (symptomatic vs. asymptomatic) and specific populations (e.g., pregnant patients).

Purpose of the Study:

• To outline appropriate initial imaging strategies for hydronephrosis of unknown etiology.
• To provide evidence-based guidance for selecting imaging modalities based on clinical scenarios.

Main Methods:

• Review of the American College of Radiology Appropriateness Criteria.
• Systematic analysis of peer-reviewed medical literature.
• Application of established evidence-grading methodologies (e.g., GRADE) and expert consensus (RAND/UCLA Appropriateness Method).

Main Results:

• For asymptomatic patients: CT urography (CTU), MR urography (MRU), or MAG3 imaging are recommended.
• For symptomatic patients: CTU, MRU, MAG3 scintigraphy, or ultrasound with Doppler are viable.
• For pregnant patients: Ultrasound with Doppler is preferred; MRU without contrast is an alternative, avoiding radiation and gadolinium.

Conclusions:

• Imaging selection for hydronephrosis is highly context-dependent.
• Guidelines emphasize patient-specific and condition-specific imaging choices.
• Evidence-based criteria and expert consensus inform recommendations for optimal diagnostic pathways.