Correlation between ultrasonographic bladder measurements and urodynamic findings in children with recurrent urinary tract infection

Abstract

To evaluate the role of bladder variables measured by ultrasonography (US) in assessing bladder dysfunction in children with urinary tract infections (UTIs). Children presenting with recurrent UTI (with or with no vesico-ureteric reflux) were prospectively recruited. At entry, each patient had US and both natural- filling (NFC) and conventional-filling (CFC) cystometry. Bladder volume and wall thickness index (BVWI) was calculated, and based on US studies and the bladder pattern on US, were classified as thick (BVWI <70), normal (70-130) and thin (>130) as previously reported. The criteria for diagnosing urodynamic patterns included normal, overactive and hypocontractile, as reported previously. The correlation between the US measured variables and urodynamic findings were then evaluated. Sixty-one children (38 boys and 23 girls; mean age 4.82 years, range 1-11) were selected for further evaluation. Of the 61 children, 16 had a normal BVWI, 36 a 'thick' value and nine 'thin'. When the BVWI was correlated with the urodynamic findings, 14 of 16 with a normal BVWI had a normal bladder pattern, whereas 92% of the patients with a BVWI of <70 had overactive bladder (P < 0.001). Among children with a BVWI of >130, six of nine had a hypocontractile pattern. The mean (sd) bladder capacity (on CFC) compared to that expected for age was significantly lower, at 56.7 (32.3)% in 'thick' bladders, vs children with normal and thin bladders, at 91.3 (23.8)% and 98.7 (31.8)%, respectively (P < 0.001). A high voiding detrusor pressure was significantly associated with children who had a thick bladder rather than normal or thin bladder (P < 0.001). This study further confirmed that the BVWI is a sensitive tool for diagnosing bladder dysfunction in children, and it can be used as a reliable guide for the appropriate choice of further invasive urodynamic studies.