[Contrast-enhanced sonourethrography versus conventional miction cystourethrography in the assessment of the urethra: preliminary study]

Abstract

Background and aims: Voiding cystourethrography (VCUG) is the first choice imaging modality for assessing the urethra, but this technique exposes patients to ionizing radiation. Cystosonography with echocontrast (CS) has proved to be a reliable technique to detect and grade vesicoureteral reflux (VUR) without exposing patients to ionizing radiation, but its capacity to adequately study the urethra has yet to be demonstrate in large series of patients. The aim of this study is to demonstrate the reliability of contrast-enhanced CS for assessing the urethra by comparing the results with those of the VCUG.

Material and methods: 108 patients were studied with ultrasound (US) using a galactose-based contrast agent. This exam was always followed by VCUG. Basal and voiding urethral US studies were performed with. Patients were studied in supine decubitus position. Girls were examined by longitudinal translabial approach, with the probe (a 7.5 MHz liner array transducer) positioned longitudinally at the introitus, to evaluate the bladder neck and urethra. In boys the transducer was initially placed longitudinally in the escrotum at ventral root of the penis to assess the bladder neck and proximal bulbar urethra, and then displaced distally toward the penile urethra. On basal study the echogenic urethral mucosa and the collapsed sonolucent urethral lumen were indentified and measured when distended. The patients were asked to void with the probe in place. During voiding attention was focused on elasticity and distention of urethral walls, as well as in the caliber of the entire urethra. Patients unable to void during either CS or VCUG were excluded.

Results: The bladder neck and the entire urethra were well demonstrate with CS. All females and 43 males showed a normal urethra both in CS and VCUG. Four patients were dignoses of posterior urethral valves (PUV) with CS and confirmed at VCUG, one patient had anterior urethral valves and 5 showed urethral stenosis at both techniques. Three patients with a vesicosphincteric dysinergia, 14 with resected PUV and one with a resected syringocele were adequately evaluated. Twelve girls showed vaginal reflux. The information provided by CS was equivalent to the VCUG in all patients but two with a syringocele (only seen on VCUG).

Conclusions: CS is a reliable imaging modality sufficiently sensitive and specific to study the urethra, adding dynamic information to VCUG and can be used as a complement to VCUG.