Fig. 1

Two-dimensional ultrasound image. (Left) At rest; (Right) At maximum Valsalva. 1 : reference line; 2 : posterior angle of the bladder and urethra; 3 : distance between the cervix and the reference line; 4 : distance between the external cervix and the reference line; 5 : distance between the ampulla of the rectum and the reference line; 6 : reference line; 7 : posterior angle of the bladder and urethra