Ultrasound diagnosis of bladder outlet obstruction in rabbits

One of the primary characteristics of partial outlet obstruction secondary to BPH is an increase in bladder mass commonly referred to as bladder hypertrophy. This condition has been simulated in rabbits by the partial ligation of the catheterized urethra. Ultrasonography has been utilized in both adult and pediatric urology to visualize the bladder and diagnose specific bladder disorders. The aim of the present study is to determine if ultrasonography can visualize bladder wall hypertrophy induced by obstruction. Partial outlet obstructions were created in NZW rabbits using standard methodologies, and then 5 to 7 days later, sonography was performed. The films were read by both the principal investigator and blinded investigators instructed to determine bladder wall thickness and from this predict the bladder weight. Then results were correlated with cystometrograms (CMGs) and whole bladder weights. Both the principal investigator and the blinded investigators were consistently able to distinguish obstructed from control bladders based solely on sonographic depictions of relative bladder wall thickness. In addition, the investigators were able to distinguish between low (control), medium, and high bladder weights based on sonography. The accuracy of predicting the bladder weights increased when cystosonograms were correlated with CMG studies. Thus, the degree of bladder hypertrophy can be accurately estimated by the combination of cmg and ultrasonography.