OBJECTIVE: To determine whether transvaginal ultrasound measurement of bladder 
wall thickness can be used as a screening test for detrusor instability in women 
with urinary symptoms.
DESIGN: A blinded prospective study.
SETTING: A London teaching hospital.
PARTICIPANTS: One hundred and eight-four symptomatic women presenting to a 
urodynamic clinic.
MAIN OUTCOME MEASURE: The detection of detrusor instability by means of 
videocystourethrography (VCU) and ambulatory urodynamics in women with a mean 
bladder wall thickness of greater than 5 mm measured by transvaginal ultrasound.
RESULTS: One hundred and eight women had a mean bladder wall thickness of 
greater than 5 mm. Ninety-four percent (102) of these women had detrusor 
instability either when undergoing VCU or ambulatory urodynamics. Seventeen 
women had a bladder wall thickness of less than 3.5 mm of whom three were found 
to have detrusor instability on VCU.
CONCLUSION: The measurement of a mean bladder wall thickness greater than 5 mm 
with transvaginal ultrasound is a sensitive screening method for diagnosing 
detrusor instability in symptomatic women without outflow obstruction.