Sonographic findings of acute urinary retention secondary to an impacted pelvic mass

Objective. To describe the sonographic findings in a series of cases of acute urinary retention due to an impacted pelvic mass. Methods. The anatomic changes of the lower urinary tract in 6 patients with impacted pelvic masses and acute urinary retention (3 cases of an impacted uterine leiomyoma and 3 cases of a retroverted gravid uterus) were evaluated with transabdominal and transvaginal sonography. Results. When patients were in the supine position, the impacted pelvic masses displaced the cervix superiorly and anteriorly, compressing the lower bladder, leading to obstruction of the internal urethral orifice. During straining, there was no limitation of urethral mobility, but the increased abdominal pressure further compressed the lower bladder. When the subjects stood, the lower bladder filled with urine. There was descent of the bladder neck, and obstruction was relieved. Conclusions. Acute urinary retention in cases of an impacted pelvic mass is caused by a displaced cervix compressing the lower bladder, obstructing the internal urethral orifice. The urethra itself is not compressed or distorted.