Urodynamic studies (UDS) are traditionally interpreted within a detrusor-centred framework derived from native bladder physiology. This paradigm becomes problematic in reconstructed lower urinary tracts, such as orthotopic neobladders and augmentation cystoplasty, where the detrusor is partially or completely absent. Despite this, conventional terminology and interpretative models continue to be applied, risking misclassification of physiological findings. We aimed to clarify what UDS measures in reconstructed systems, identify key interpretative pitfalls, and propose a physiology-based framework that incorporates time-dependent changes in bowel reservoirs and their impact on compliance and pressure behaviour.

This narrative review synthesises evidence from International Continence Society (ICS) standardisation documents, urodynamic technical guidance, and reconstructive urology literature. Particular focus was given to orthotopic neobladder and augmentation cystoplasty physiology, abdominal pressure transmission, bowel peristalsis, and video urodynamics (VUDS). Concepts were integrated to develop a clinically applicable interpretation model aligned with ICS terminology while acknowledging its limitations in reconstructed systems.

In reconstructed lower urinary tracts, pressure signals primarily reflect the interaction between reservoir compliance, abdominal pressure transmission, outlet resistance, and bowel wall behaviour rather than detrusor contractility. The calculated parameter detrusor pressure (Pdet = Pves − Pabd) remains mathematically valid but loses physiological specificity in the absence of detrusor muscle.
Over time, bowel segments used in urinary reconstruction undergo structural adaptation, including wall thickening, fibrosis, and reduced elasticity. These changes may develop progressively over months to years and contribute to declining compliance and rising storage pressures. Additionally, detubularisation reduces coordinated bowel peristalsis; however, the absence or attenuation of phasic contractions may impair pressure redistribution within the reservoir, further influencing compliance behaviour.
Phasic rises in Pves or Pdet are frequently observed and may be misinterpreted as detrusor overactivity. In reconstructed systems, such pressure changes commonly arise from abdominal pressure transmission, incomplete pressure subtraction, or residual bowel activity. Misinterpretation is exacerbated by technical factors, including suboptimal abdominal pressure recording, catheter positioning, and the use of air-charged systems with altered pressure transmission characteristics.
VUDS enhances interpretation by correlating pressure events with anatomical findings, allowing differentiation between clinically relevant pressure changes and artefacts. In patients with post-reconstruction incontinence, particularly following artificial urinary sphincter implantation, UDS distinguishes outlet-related leakage from reservoir-driven mechanisms such as reduced compliance, pressure-driven leakage, or incomplete emptying.

UDS in reconstructed lower urinary tracts should be interpreted as an assessment of reservoir behaviour and pressure safety rather than detrusor function. Time-dependent structural changes in bowel segments and altered peristaltic activity must be considered when evaluating compliance. Descriptive terminology consistent with ICS principles should be used, avoiding inappropriate attribution of findings to detrusor activity when absent.

Urodynamics remains a valuable diagnostic tool after bladder reconstruction, but only when interpreted within the correct physiological context. Recognition of reservoir-based pressure generation, evolving compliance characteristics, and non-detrusor pressure sources is essential to avoid misclassification and guide appropriate management. A reconstruction-specific interpretative framework improves diagnostic accuracy and aligns urodynamic assessment with underlying physiology.