Ultrasonography of the urinary tract in children, with special emphasis on the urinary bladder

Abstract

Ultrasonography (US) is routinely used in children with urinary tract disorders. However, the bladder is usually evaluated with invasive methods, e.g. voiding cystourethrography (VCU) and cystometry. The first aim of this thesis was to develop and evaluate a non-invasive US method for assessment of the detrusor, the anatomical bladder wall structure most likely to be affected by disorders hampering bladder function. The most important issue in evaluating children with urinary tract infection (UTI) is to identify individuals who are at risk of permanent renal damage (PRD). The role of US in this respect is debated. The second aim of this thesis was to evaluate US for identification of infants at risk of PRD after symptomatic UTI. I. A transabdominal US technique was developed, assessing the thickness of the low echogenic detrusor layer of the urinary bladder wall at anatomically defined locations. The method proved reliable, with an intra- and interobserver variability of 0.2 mm. II. Detrusor thickness (DT) was measured in 150 healthy children, aged 0-13 years. DT decreased with increasing bladder fullness and increased with age. Boys had slightly thicker detrusors than girls. The upper limit of normal for DT was 1.5-2 mm, depending on age and bladder fullness.III. DT was measured in 66 children with neurogenic bladder disturbance (myelomeningocele). The DT was thinner than in normal children, and there was no correlation between DT and bladder- or renal function, treatment with anticholinergics or trabeculation of the bladder at VCU. It appears that treatment with intermittent catheterisation and anticholinergics are effective in preventing bladder wall thickening. IV. US, DMSA scintigraphy and VCU were performed in 191 infants with symptomatic, first time UTI. One year later children with abnormal scintigraphy had a follow-up scintigraphy. US had a low sensitivity (43%) in predicting permanent renal damage (PRD) and in detecting dilating reflux (56%) as a risk factor for PRD. Dilating reflux, obstruction and anomaly were confirmed as important risk factors for PRD, but was found in only half of the children who developed PRD, and this probably contributed to the low ability of US to predict PRD.