Effect of bladder volume and compliance on ultrasonographic measurement of bladder wall thickness in children with neurogenic bladder dysfunction

Background Spina bifida is the most common cause of neurogenic bladder dysfunction in children. Measurement of bladder wall thickness (BWT) is non-invasive, lowcost, and may be complementary to urodynamics in demonstrating bladder condition. It is still unknown the wall thickness response to volume change in bladders with different compliance states. Objective To determine the most appropriate measurement technique by revealing the differences in measurements performed in different compliance and volume conditions in children with neurogenic bladder. Study design In the prospective study in 2022, patients with spina bifida who continued their urological follow-up in our spina bifida center were included. Patients with a diagnosis of the neurogenic bladder who performed clean intermittent catheterization at least 4-6- 6 times a day and had a recent urodynamic result in the last 6 months were included in the study. According to urodynamic results, patients were divided into two groups normocompliant (NC) and low-compliant (LC) bladders. BWT measurements were made from the anterior, posterior, right lateral, and left lateral walls of the bladder 3 times as full, half-volume, and an empty bladder. Results The study included 50 patients (NC group n:21, LC group n:29). The mean age of 24 female and 26 male patients was 6.45 + 4.07 years. In all BWT measurements, a significant increase in wall thickness was observed with decreasing bladder volume. The best correlation between bladder volume and BWT was found in the anterior wall with a weak negative correlation (p = 0.049, r =-0.280). However, lateral wall measurements were significantly higher in low compliant patients compared to normocompliant patients when the bladder was full. The mean right lateral wall thickness was 1.58 + 0.68 mm in the NC group and 2.18 + 1.35 mm in the LC group (p = 0.044). Left lateral wall thickness was 1.45 + 0.44 mm in the NC group and 2.02 + 1.4 mm in the LC group (p = 0.033). Discussion Although standardization has been tried to be achieved in BWT measurements, we understand from the studies in the literature that there is no unity in practice. Conclusion Lateral wall measurements were found to be significantly higher in LC patients compared to normocompliants in full bladder suggesting that more accurate BWT follow-up can be performed with lateral wall measurements in neurogenic bladder patients if bladder compliance is low. The present study seems to be the first study in the literature in which bladder compliance and ultrasonographic bladder wall thickness measurements were evaluated together in children with neurogenic bladder dysfunction.