BACKGROUND A remote-controlled steering arm was developed that allows the ultrasound probe to be held on the perineum under ultrasound image guidance with the woman seated on a commercially available bedside commode. TECHNIQUE The arm's servomechanism monitors contact pressure between the scanning head and the perineum, keeping constant gentle pressure on the perineum so that the transducer follows perineal movement. EXPERIENCE Twenty patients with urinary incontinence and ten normal volunteers were examined during two voiding episodes, one without perineal ultrasound and one with ultrasound. Ultrasound images and intrarectal pressure measurements were displayed simultaneously on a video monitor. Bladder and urethral visibility and behavior were analyzed during bladder emptying. Of the 30 women, 28 were able to void, with and without the ultrasound probe applied. Two women were not able to urinate under observation either with or without sonography. The bladder base, bladder neck, and upper two-thirds of the urethra were visible throughout voiding in the 28 women able to void. Bladder neck opening could be observed in all of the 28 women. Bladder neck descent during initiation of voiding occurred in 17 women, whereas 11 voided without bladder neck descent. CONCLUSION The use of this device facilitates ultrasound evaluation of micturition in the physiologic sitting position and allows bladder neck behavior to be seen during bladder emptying.