The urethra is the final segment of the urinary tract, a tube that carries urine from the bladder to the outside of the body. In males, the urethra is approximately 20 centimeters long and also serves as the passage for semen during ejaculation. In females, the urethra is much shorter, about 4 centimeters long. The urethra is not commonly evaluated by conventional ultrasound, but it can be assessed in certain situations. Transperineal or translabial ultrasound can evaluate urethral diverticula (outpouchings) in women, and sonourethrography (using a contrast agent) can evaluate urethral strictures in men. Post-void residual measurement indirectly assesses urethral function, as elevated residuals may suggest urethral obstruction.
Sonography Term