BACKGROUND: The role of Kidney and Bladder Ultrasound (KBUS) as a routine exam in patients with Lower Urinary Tract Dysfunction (LUTD) remains unclear. Recently, a study found that only 4.5% of children with LUTD presented clinically significant KBUS findings. Worse symptoms score and urinary tract infection (UTI) were predictors of KBUS alteration. Because of possible selection bias or difference in the symptom’s presentation, this study aims to describe the KBUS findings in children and adolescents with LUTD and to evaluate possible associated factors of abnormal imaging.METHODS: This is a retrospective study involving patients diagnosed with LUTD who underwent KBUS. KBUS abnormality was defined as the presence of hydronephrosis (by SFU classification), bladder wall thickening (> 3 mm) and reduced renal parenchyma (suggestive of renal scaring). The KUBS abnormality was considered significant when hydronephrosis grade 3-4, parenchyma appearance suggestive of renal scaring, and/or bladder thickening were present. The subsets of LUTD analyzed were Hyperactive and Hypoactive Bladder, Voiding Postponement, Dysfunctional Voiding and Bladder and Bowel Dysfunction. A positive UTI history was defined as the presence of a positive urine culture. The association between the history of UTI, urgency, daytime incontinence, high voiding frequency, infrequent voiding, strength to void, nocturia, holding maneuvers, enuresis, constipation, subsets of LUTD and KBUS abnormalities was evaluated using Pearson’s Chi-square. To assess the DVSS predictive model, a Receiver Operating Characteristic (ROC) curve was generated, and the Youden index was calculated to determine the DVSS cutoff for predicting abnormal imaging.RESULTS: 106 patients were included. 55 (51.9%) were female. The median age was 8 (IQR 5-11) years. 10 (9.4%) patients had abnormal KBUS. Of those, 4 (4%) had clinically significant findings; 3 patients had bladder wall thickening and one had hydroureteronephrosis grade 3 and bladder wall thickening. Additional findings were grade 1 and 2 hydroureteronephrosis. The subsets of LUTD and clinically significant KBUS findings were associated; 2 patients were diagnosed with Voiding Postmomnent and 2 with Bladder and Bowel Dysfunction (p<0,043). A DVSS cutoff could not predict KBUS abnormality (p=0,943).CONCLUSIONS: 4.7% of patients with LUTD presented clinically significant KBUS findings. 1 patient had a significant kidney finding at ultrasound that could benefit from this exam. All patients with bladder wall thickness would be picked by the bladder ultrasound for post residual urine measurement. The clinical significance of the association with Bladder and Bowel Dysfunction and Voiding Postponement is still uncertain. Therefore, we believe that kidney ultrasound is not necessary for LUTD patient’s routine workup.
