Detrusor Underactivity: Modern Definitions, Diagnostic Criteria, and Clinical Phenotyping

Abstract Purpose of Review Detrusor underactivity (DU) is a common but underrecognized contributor to lower urinary tract symptoms (LUTS), urinary retention, and impaired bladder emptying. Despite its prevalence, progress in DU research and clinical care has been hindered by ambiguous terminology, heterogeneous diagnostic criteria, and the absence of validated classification systems. This review summarizes recent advances in DU definitions, diagnostic approaches, and clinical phenotyping, with emphasis on the 2023 International Continence Society (ICS)-Society of Urodynamics, Female Pelvic Medicine and Urogenital Reconstruction (SUFU) Standardization Report and recent International Consultation on Incontinence Research Society (ICI-RS) initiatives. Recent Findings The 2023 ICS-SUFU Standardization Report introduced important refinements to DU terminology, distinguishing a single detrusor underactive voiding contraction (DUVC) from the broader diagnosis of DU. The report also renamed the Bladder Contractility Index as the ICS Detrusor Contraction Index (ICS-DCI), emphasizing that routine pressure-flow studies assess detrusor contraction performance rather than intrinsic detrusor contractility. In women, limitations of male-derived indices have prompted increasing interest in the projected isovolumetric pressure 1 (PIP1) and female-specific nomograms, although clinically meaningful thresholds remain incompletely validated. Emerging approaches, including noninvasive prediction models, bladder imaging biomarkers, artificial intelligence-based analysis, and molecular biomarkers, may improve diagnosis and facilitate phenotyping. Summary DU is evolving from a poorly standardized urodynamic diagnosis toward a heterogeneous condition requiring sex-specific diagnostic approaches and multidimensional phenotyping. Future progress will likely depend less on identifying a single diagnostic threshold and more on integrating etiopathological, urodynamic, structural, functional, and molecular information to support individualized management and future therapeutic development. Key points • Detrusor underactivity (DU) is a common but underrecognized contributor to lower urinary tract symptoms, urinary retention, and impaired bladder emptying. • Epidemiologic estimates vary widely because diagnostic criteria are inconsistent, UAB/DU-specific coding is lacking, and real-world documentation is often incomplete. • The 2023 ICS-SUFU Standardization Report distinguishes detrusor underactive voiding contraction (DUVC) from the diagnosis of DU and clarifies that routine pressure-flow studies assess detrusor contraction performance rather than intrinsic contractility. • Female-specific diagnostic frameworks, including PIP1 and emerging nomograms, represent important advances but require further validation. • DU is increasingly recognized as a heterogeneous condition encompassing multiple etiopathological, urodynamic, structural, functional, and molecular phenotypes. • Noninvasive diagnostic models, imaging biomarkers, molecular biomarkers, and artificial intelligence-based approaches may improve diagnosis and support phenotyping. • Future research should prioritize diagnostic standardization, sex-specific validation, longitudinal outcome studies, multidimensional phenotyping, and evidence-based clinical guidelines.