=Treatment.=--As retroflexion does not usually cause obstruction of the menstrual flow, the treatment need not be directed toward rendering patulous the cervical canal, as in the case of anteflexion. Retroflexion is always associated with retroversion, and the methods that correct the retroversion place the uterus in such a position that the intra-abdominal pressure acts on the posterior face of the uterus and gradually reduces the flexion. Therefore the treatment of retroflexion and of retroversion may be considered together. Retroversion is treated by the vaginal pessary and by operation. _The vaginal pessary_ is an instrument to be worn in the vagina, and designed to retain the uterus in its normal position. A great many different kinds of pessaries have been invented. The large number of different-shaped instruments proves the inefficacy of the pessary as a means of treatment in many cases of retroversion. The best pessaries for retroversion are the Hodge (Fig. 90, A), the Smith (Fig. 90, B), and the Thomas (Fig. 90, C). These instruments are made of hard rubber. They consist of an upper and a lower transverse bar joined by two lateral bars. They are so shaped that when introduced into the vagina they correspond very closely to the curvature of the vaginal slit. [Illustration: FIG. 90.--Pessaries for retroversion: A, Hodge pessary; B, Smith pessary; C, Thomas pessary.] Fig. 91 shows a side view of a pessary in position, and it will be observed that the curves of the instrument are closely adapted to the curves of the posterior vaginal wall, upon which it lies. The vaginal pessary retains the uterus in place by raising the posterior vaginal fornix and keeping tense the posterior vaginal wall. It will be observed that the posterior wall of the vagina runs over the upper transverse bar of the pessary like a rope over a pulley; therefore there is maintained a continuous traction in an upward and backward direction upon the cervix, and a resulting continuous tendency to throw the fundus uteri in a forward position (Fig. 91). The tension of the posterior vaginal wall and the traction upon the cervix vary with the position and occupation of the woman, and are increased by anything that increases the intra-abdominal pressure. The vaginal pessary does not maintain the uterus in place by pressure upon the body of the uterus, nor does the vaginal pessary correct a retrodisplacement. The uterus should be restored to its normal position as nearly as possible before the pessary is introduced. [Illustration: FIG. 91.--The retroversion pessary in position. The arrow shows the direction of the traction of the posterior vaginal wall upon the cervix.] Replacement of the uterus may be effected in one of two ways: by bimanual reposition while the woman is in the dorsal position; or by instrumental reposition while the woman is in the knee-chest position.