Bladder debris on ultrasound as a predictor for positive urine culture
Reviewed by Ravindar Anbarasan

One of the common ultrasound findings in children who undergo renal tract evaluation is ‘debris in the bladder’. The aetiology of bladder debris is varied and the likelihood that urinary debris represents positive urine culture is debatable. The authors of this paper hypothesised that bladder debris will increase the likelihood that a urine culture is positive compared to those without bladder debris and performed a retrospective review on 445 children aged 0-17 years who had a catheter sample of urine sent for urine culture prior to a micturating cystourethrogram (MCUG) and who also had a renal and bladder ultrasound up to one week prior, the day of, or up to two days after their urine studies. Presence of bladder debris and debris severity was recorded. Positive urine culture was defined as a single bacterial strain >50,000 CFU/mL. The positive urine culture rate was 20%, and the rate of bladder debris was 22%. The mean age for those with and without bladder debris was 6.6 and 5.5 years, respectively (p=0.02). Twenty-three percent of girls had bladder debris, compared to 12% of boys (p=0.04). The sensitivity and specificity for bladder debris in detecting positive urine cultures was 52% and 86%, respectively. Forty-seven percent of those with bladder debris had positive cultures, compared with 12% of those without debris (p<0.01). The relative risk of positive urine culture if debris is present is 3.90 (95% CI 2.73-5.55). Hydronephrosis or vesicoureteral reflux did not affect the relationship between bladder debris and positive urine cultures. They concluded that nearly half of paediatric patients undergoing urological evaluation found to have bladder debris on ultrasound would have a positive urine culture. Debris is noted more commonly in girls and at a slightly higher age. The presence of debris is associated with a four-fold increase in detecting a positive urine culture, regardless of debris severity, hydronephrosis, or vesicoureteral reflux. Given this, it is of value to routinely document and look for the presence of any amount of bladder debris seen on ultrasound, as this finding can be used to augment clinical decision-making and warrants strong consideration for obtaining urine culture. 

Bladder debris on ultrasound as a predictor for positive urine culture in a pediatric population.
Stevenson SM, Lau GA, Andolsek WC, et al.
JOURNAL OF PEDIATRIC UROLOGY
2018;14(3):254.e1-254.e5.