=Torsion of the Pedicle, or Axial Rotation.=--Ovarian tumors occasionally rotate upon their axes, so that the structures that form the pedicle become twisted. The severity of the symptoms that arise from this accident depends upon the degree of compression to which the vessels of the pedicle are subjected from the torsion. The accident is not now as common as formerly, because the tumor is, as a rule, now removed as soon as it is recognized, and many of the accidents that were described as very frequent by the older writers are avoided. The many recorded cases--chiefly of a date before our present surgical era--show that axial rotation occurred in about 10 per cent. of the cases of ovarian and parovarian tumors. Rokitansky found torsion of the pedicle in 12 per cent. of all cases of ovarian tumors, and in 6 per cent. of the cases it was the cause of death. The cause of axial rotation is unknown. It has been attributed to alternate distention and evacuation of the bladder, to the passage of feces through the rectum, and to a sudden jar or motion of the body. The accident is especially likely to occur when an ovarian cyst complicates pregnancy or when both ovaries are cystic. Torsion of both pedicles has been found in women suffering with bilateral ovarian cysts. Torsion of the pedicle is more apt to occur in cysts of medium and small size than in the large tumors. Torsion of the pedicle affects equally tumors of the right and left sides. The direction of rotation is usually toward the median line, though it may take place in the reverse direction. There is considerable variation in the amount of rotation. In some cases the pedicle has twisted through but half a circle, while in others twelve complete twists have been found. A pedicle twisted in this way resembles a rope. Such a high degree of torsion is the result of a slow or chronic process. The rotation of the tumor takes place so gradually, or the arrangement of the blood-vessels in the pedicle is such, that no appreciable effect upon the tumor is produced, and no symptoms arise from it. The operator frequently meets examples of such slow torsion in removing ovarian tumors. In extreme cases the twisting progresses until the blood-supply through the pedicle is arrested, and the cyst may become freed from its peduncular attachment. If adhesions had formed to the cyst-wall, the vitality may be maintained through these channels; the tumor, in fact, becomes transplanted. This phenomenon is most frequent with dermoids.