Development of a Pediatric Age-Based and Weight-Adjusted Nomogram for Bladder Volumes Associated With Successful Completion of Transabdominal Pelvic Ultrasound (TPU).

Objective: To develop a nomogram for pediatric bladder volumes associated with the successful completion of transabdominal pelvic ultrasound (TPU) in female pediatric patients presenting with lower abdominal and/or pelvic pain in the emergency department. This study hypothesizes that the target bladder volumes for successful TPU vary by age and weight.

Methods: We retrospectively calculated bladder volumes on all successful transabdominal pelvic ultrasound studies during a 2-year period for patients 8 to 18 years old by ellipsoid bladder volume formula using the largest cross-sectional areas captured on transverse and longitudinal cine clips. Measurements were collected by 2 study personnel with initial measurements validated by a pediatric radiologist. Bladder volume by age and weight percentile groups were descriptively analyzed, and a quantile regression model was used to regress bladder volume on age adjusting for patient weight.

Results: We analyzed bladder volumes from 1030 successful transabdominal pelvic ultrasound studies. The greatest drop in median volume was seen amongst non-overweight children in younger age groups. Nomogram bladder volumes for transabdominal pelvic ultrasound increase consistently with age and weight until approximately 13 years old and 60 kg, respectively, with minimal change thereafter in patients 13 to 18 years old.

Conclusions: We provide a pediatric age-based and weight-adjusted nomogram for bladder volumes associated with successful transabdominal pelvic ultrasound imaging. Further evaluation of its use is warranted to decrease inefficiency in bladder filling prior to TPU completion and improve timeliness in diagnosing pelvic emergencies.