Retroflexion means a bending backward of the uterine axis. The axis of the body of the uterus is normally inclined forward at an obtuse angle with the axis of the cervix. When the axis of the body of the uterus is inclined backward at an angle with the axis of the cervix, retroflexion exists. Retroflexion may vary in extent from an angle very little less than 180 degrees to an angle considerably less than 90 degrees ([Fig. 87]).
Fig. 87.—Retroflexion of the uterus.
Retroflexion and retroversion usually coexist. The conditions are due to similar causes. They may originate simultaneously, or one condition, occurring primarily, may induce the other.
An infinite number of degrees of retroversion may exist. For convenience of clinical description three degrees have been described. In the first degree the fundus uteri is directed upward approximately toward the promontory of the sacrum. In the second degree the uterus lies transversely across the pelvis, the fundus and the cervix being at about the same level. In the third degree the retroversion is extreme, and the fundus lies below the level of the cervix ([Fig. 88]).
Retroversion of the uterus is progressive. It usually proceeds from bad to worse. As soon as the downward abdominal pressure begins to act upon the anterior face of the uterus there is a continuous force increasing the retroversion.
There are many causes of retroversion and retroflexion.
Fig. 88.—Diagram of the degrees of retroversion of the uterus.
The disease may be congenital. Extreme retroflexion has been found in the uterus of the new-born infant. Congenital retroversion and retroflexion may be due to imperfect development, and resulting imperfect invagination of the cervix. The condition may also be caused by arrest of development of the posterior wall of the uterus; the anterior wall thus outgrowing the posterior.