“…In their study, Khullar et al averaged the bladder wall thickness at the trigone, dome, and anterior bladder wall to develop criteria for detection of detrusor overactivity, others assumed that measurement of the bladder dome is sufficient to define bladder wall thickness, even if they did not find that women with detrusor overactivity had an appreciably thicker bladder wall than other study groups (Khullar et al, 1996;Yang & Huang, 2003). US has also been shown to be a reproducible method of assessing urethral sphincter volume (Digesu et al, 2009). Using 2D ultrasound, on axial US images the normal urethra has a characteristic target-like appearance and is seen as composed by four concentric rings of different echogenicity (Minardi et al, 2007).…”