Contrast radiographic evaluation of morphological variability of the canine male urethra

Abstract

Positive contrast retrograde urethrography is a widespread technique used in clinics due to its providence of information on morphological features such as size, shape and position of the urethra as well as its luminal content. Evaluation of the urethral diameter is difficult since it according to present experience varies among individuals. When evaluating contrast radiographs not taken during pre-distention of the urinary bladder the lumen of the prostatic portion of the urethra is showing a variable diameter. Slight narrowings at the ischial arch, pelvic brim and caudally to the prostate is generally seen in the otherwise normally uniform urethra. The purpose of this study was to find out whether it is possible to obtain standard values for the various portions of the urethra without pre-distention of the urinary bladder and if these values are usable to be able to diagnose abnormalities in the urethral diameters. These standard values would be considered to represent the normal urethral diameters. 35 positive contrast retrograde urethrographies of male dogs were used. The dogs chosen were of different breeds and age. The urethral diameters were measured at ten points including one prostatic diameter, three pelvic, four perineal and two penile diameters. The average of each urethral segment was calculated. To be able to compare the different sized individuals and to correct magnification differences the measurements were firstly obtained in millimeters and then converted into Pelvic Unit % (PU %). Values obtained in this study showed that the average diameter of the prostatic portion is 4,7 PU %, the pelvic portion is in average 6,9 PU %, the perineal portion 6,1 PU % and the penile portion is in average 6,6 PU %. These values may be helpful in the clinical evaluation of the urethral diameters.