Ultrasound measurement of bladder wall thickness in the assessment of voiding dysfunction

Purpose: Ultrasound measurement of bladder wall thickness has been proposed as a useful diagnostic parameter in patients with bladder outlet obstruction and other voiding dysfunctions. We assessed bladder wall thickness measurement as a noninvasive test in patients with suspected bladder outlet obstruction or overactive bladder syndrome. Materials and Methods: Transabdominal ultrasound measurement of bladder wall thickness was performed during urodynamic study in 180 patients with nonneurogenic voiding dysfunction. Two measurements of anterior bladder wall thickness, 1 cm. apart in the midline and averaged, were obtained at 200 ml filling. Bladder wall thickness findings were correlated with urodynamic diagnoses. Results: A total of 180 patients with an average age of 62 years (range 20 to 94) were recruited, comprising 73 males and 107 females. Of the patients 69 had normal urodynamics, 39 had bladder outlet obstruction, 38 had increased bladder sensation on cystometry and 34 had detrusor overactivity. Bladder wall thickness was 1.1 to 4.5 mm in all groups. Males had a slightly thicker bladder wall than females (mean 2.1 vs 1.9 mm, p = 0.064). Mean bladder wall thickness in patients with normal urodynamics, bladder outlet obstruction, detrusor overactivity and increased bladder sensation was 2.0, 2.1, 1.9 and 1.8 mm, respectively. No significant difference was found between the groups (ANOVA p = 0.064, not significant). In particular there was no difference in bladder wall thickness between patients with normal urodynamics, and those with bladder outlet obstruction (p = 0.31) or detrusor overactivity (p = 0.309). Conclusions: Bladder wall thickness is remarkably uniform in patients with nonneurogenic voiding dysfunction. Therefore, it cannot reliably predict bladder outlet obstruction or detrusor overactivity. Bladder wall thickness measurement does not provide an alternative to urodynamic studies for diagnosing voiding dysfunction.