Point-of-Care Ultrasound Evaluation of Bladder Wall Thickness in Suspected Acute Cystitis

Acute cystitis is a frequent emergency department (ED) diagnosis typically evaluated using urinalysis, which may be delayed by specimen collection and processing. Point-of-care ultrasound (POCUS) is widely used in emergency medicine for infectious and inflammatory conditions, where organ wall thickening may indicate pathology. While bladder wall thickening has been described on cross-sectional imaging in cystitis, its diagnostic value using POCUS remains unclear. The aim of this study is to identify whether anterior bladder wall thickness (BWT) measured by POCUS correlates with acute cystitis diagnosed by urinalysis in adult ED patients.

This prospective observational study was conducted in an academic community ED. Adult patients (≥18 years) with clinical suspicion for urinary tract infection were enrolled. Exclusion criteria included pregnancy, incarceration, chronic indwelling Foley catheter, prior bladder surgery, or known bladder malignancy. POCUS examinations were performed by emergency medicine residents and attending physicians. Anterior BWT and bladder volume were measured. Urinalysis served as the reference standard. Primary endpoints were anterior BWT >3 mm at bladder volumes >250 mL and BWT >5 mm regardless of volume. Secondary outcomes included the presence of echogenic bladder debris.

Thirty-four patients were enrolled, of whom 23 were urinalysis-positive. Using predefined thresholds, anterior BWT demonstrated limited diagnostic performance, with a sensitivity of 35% and specificity of 45%. Scatter plot analysis of bladder volume versus BWT revealed substantial overlap between urinalysis-positive and negative patients, indicating poor discriminatory ability. Predictive values were modest, suggesting limited standalone utility.

In this pilot study, anterior bladder wall thickness measured by POCUS showed poor sensitivity and specificity for diagnosing acute cystitis. Significant overlap between groups limits its utility as a standalone diagnostic tool. Larger studies with standardized bladder volume measurements are needed to better define the role of POCUS in evaluating suspected cystitis.