ACR Appropriateness Criteria® Recurrent Lower Urinary Tract Infections in Females: Update 2026.

Urinary tract infections (UTIs) are common in females and usually originate in the lower urinary tract. Recurrent UTIs, defined as three infections within 12 months, may be uncomplicated, occurring without underlying abnormalities, or complicated, when structural, functional, or systemic factors increase susceptibility. Complicated and recurrent UTIs, including those during pregnancy, require careful evaluation because pregnancy and comorbidities increase the risk of recurrence and serious maternal and fetal complications. This review outlines initial imaging strategies for uncomplicated adults, complicated adults, and pregnant patients. In uncomplicated patients without risk factors, routine imaging is generally not indicated due to low diagnostic yield. In complicated patients, imaging is appropriate to evaluate for obstruction, stones, diverticula, fistulas, or other structural causes; ultrasound is a reasonable screening tool, whereas CT urography is typically preferred for comprehensive evaluation. In pregnant patients, imaging is reserved for suspected complications, with ultrasound preferred and noncontrast MRI used selectively. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.