Abstract
Background
The current standard for diagnosing vesicoureteral reflux (VUR) in children is a voiding cystourethrogram (VCUG), which requires an accurate estimation of bladder capacity to be performed appropriately. However, in clinical practice, the amount of contrast instilled into the bladder often exceeds the estimated capacity, raising concerns among parents, radiologists, and technologists. The potential harm caused by exceeding the estimated capacity set by the American Academy of Pediatrics (AAP) and American College of Radiology (ACR) has not been studied.
Objective
The purpose of this study was to compare the actual bladder capacity of children undergoing VCUG with existing formula-derived estimates, and to describe any adverse effects of bladder overdistention during VCUG.
Materials and Methods
This retrospective study involved the review of 884 consecutive VCUG performed over a period of 3 years. The data was divided into three age groups: less than age 2, ages 2 through 14, and greater than age 14. Cases with underlying conditions that could artificially increase bladder capacity, such as neurogenic bladders or vesicoureteral reflux, were excluded from the analysis. Descriptive statistics were used to summarize the results.
Results
Out of the 884 reviewed VCUG studies reviewed over the 3-year period, a total of 440 normal VCUG procedures were included in the analysis. Among these, 284 VCUGs (65%) had bladder volumes that exceeded the expected bladder capacity set by the AAP and ACR. Specifically, out of the 261 VCUGs performed on children under 2 years of age, 164 (63%) VCUG exceeded the expected capacity. In the age group between 2 and 14 years, out of the 165 VCUGs performed, 113 (68%) exceeded the expected bladder capacity. Among the 14 VCUGs performed on children older than 14 years of age, seven (50%) exceeded the bladder capacity. Importantly, no adverse effects were observed or reported during or shortly after the VCUG in the 32 VCUG studies (7.3%) that required a contrast volume of more than two times the AAP estimates of bladder capacity. Additionally, no adverse effects were observed or reported immediately or within the next week in the 22 VCUG studies (5%) that required a contrast volume of more than three times the AAP estimates. This included six children who received 700 mL or more of contrast.
Conclusion
This study suggests that current guidelines often underestimate bladder capacity, and exceeding the expected bladder capacity appears to be reasonably safe without the occurrence of complications.