Uterine version and flexion: anteverted, anteflexed uterus
Version is the angle between the vagina (bottom of the tract) and cervix (the womb's neck); flexion is the angle between cervix and uterine body (the womb's main muscular part).
Remember
Version belongs to the vagina and cervix and flexion to the cervix and uterine body; under 180° is ante- (forwards), over 180° is retro- (backwards), and the commonest position is anteverted (cervix tilted forwards) and anteflexed (body bent forwards).
Memory aid
version starts with V, like vagina
Version is the angle that begins at the vagina, so flexion is the one further up, at the cervix and the uterine body.
Doctors describe where the female reproductive tract points (here, the vagina, cervix and uterine body) by drawing three axes. These are imaginary straight lines, one for the vagina (the bottom of the tract), one for the cervix and one for the uterine body, and each shows the direction that part points. Two angles lie between them.
Version is the angle between the axis of the vagina and the axis of the cervix. If it is under 180°, the cervix is anteverted: ante- means forwards, so the cervix tilts forwards. If it is over 180°, the cervix is retroverted: retro- means backwards, so the cervix tilts backwards.
Flexion is the angle between the axis of the cervix and the axis of the uterine body. Under 180° the uterus is anteflexed (bent forwards over the cervix). Over 180° it is retroflexed (bent backwards).
The two angles are judged separately, so any combination can occur. The commonest position is anteverted and anteflexed, which normally puts the uterus behind and above the bladder and in front of the rectum. Retroversion and retroflexion are rarer, but they are still variants of normal, and they can cause problems such as pain in pregnancy.
The round ligament (a fibrous band running from the uterus) helps to hold the uterus in its anteverted position. It supports the angle rather than defining it.
Key facts
- Version
- the angle between the axis of the vagina and the axis of the cervix.
- Flexion
- the angle between the axis of the cervix and the axis of the uterine body.
- Prefix ante-
- a version angle under 180° gives ante- (forwards), so the cervix is anteverted; a flexion angle under 180° gives ante-, so the uterus is anteflexed.
- Prefix retro-
- a version angle over 180° gives retro- (backwards), so the cervix is retroverted; a flexion angle over 180° gives retro-, so the uterus is retroflexed.
- Commonest position
- anteverted and anteflexed.
- Rarer positions
- retroversion and retroflexion are variants of normal, but they can cause problems such as pain in pregnancy.
- Combinations
- any combination of version and flexion can occur.
Exam traps
- Forward bending of the uterine body relative to the cervix is anteflexion, not version, because version describes how the cervix sits relative to the vagina.
- The round ligament helps to maintain the anteverted position, but it does not define version, because version is an angle and the ligament is a supporting structure.
- An angle under 180 degrees between the cervix and the uterine body describes anteflexion, not anteversion, because that angle is flexion; anteflexion often occurs together with anteversion, but version is the separate angle between the vagina and the cervix.
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