Uroflowmetry combined with simultaneous measurement of abdominal pressure by tocodynamometer.

We used a guard-ring tocodynamometer to detect abdominal straining simultaneously with uroflowmetry in 19 normal volunteers, 63 patients with benign prostatic hyperplasia and 25 with a neurogenic bladder. The pressure curves obtained by the tocodynamometer were similar to the intrarectal pressure curves simultaneously measured by an intrarectal balloon. The frequency of straining in patients with benign prostatic hyperplasia did not differ significantly from that in normal volunteers and did not decrease postoperatively. In these patients abdominal straining did not produce a synchronously increased flow rate. Patients with a neurogenic bladder frequently voided with straining. Abdominal straining tended to produce a synchronously increased flow rate in patients with lesions in the sacral cord or peripheral nerves but not in patients with neural lesions above the sacral cord. The presence of urinary flow without straining was considered to signify an intact voiding reflex. We believe that this method is simple and provides much more information than uroflowmetry alone to evaluate voiding dysfunctions.