This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Urinary System, Subject name: Gynaecology & Obstetrics
[{'content': 'In a patient who complains of urinary incontinence, a cystometrogram is performed to \nSelect and explain. \nA. Determine urethral length, B. Rule out an unstable trigone, C. Diagnose stress urinary incontinence, D. Determine if a patient has normal bladder sensation', 'role': 'user'}, {'content': 'Answer: D \nExplanation: As a catheter is introduced for performing a cystometrogram, measurement of residual urine is obtained. During the cystometrogram, a normal first sensation is of fullness felt at 100 mL. Urge is felt at approximately 350 mL, with maximum capacity at 450 mL. The primary reason to perform a cystometrogram is to rule out uninhibited detrusor contractions. The cystometrogram is a urodynamic test, and it cannot determine whether ureterovesical reflux exists. The degree of reflux can be evaluated with the voiding cystogram, a radiologic test.', 'role': 'assistant'}]