Uterine position in the pelvis is defined by two angles. The first one is the angle between the axis of the uterine body and axis of the cervix, called flexion. The second represents the relation between the axis of the cervix and the axis of the vagina, and it is called version. Having this in mind, there are four different positions of the uterus which can be determined by transvaginal or transabdominal ultrasound. By the natural position of the uterus in the pelvis, doctors consider anteflexion with anteversion.
Cervix represents the lower part of uterus about 2 inches long, and it is located between the vagina and the uterine body. The uterine body is the upper part of uterus shaped like a pear and sits at the top of the cervix. Another name for uterine body is fundus. Women who have had a baby can have a larger fundus, whereas those who haven’t had a baby and are in menopause, can have it a smaller in size.
A number of ligaments are responsible for attaching cervix and fundus to the pelvic sidewalls. They are flexible, thus allowing the uterus to tilt backward or forward leading to disorder in natural position inside the pelvis.
Characteristics Of Uterus
As already mentioned, uterus is shaped like a pear. Its measures are: 7.5cm in length, 5cm width, and depth is 2.5cm. The wall of the uterus consists mainly of a thick muscle, covered by an endothelium called endometrium, limiting uterine cavity. This cavity is located inside the fundus and it is the part where fertilized egg will grow into the baby. This cavity is closed by the cervix, thus separated from the vagina.
Four different position uterus can take inside the pelvis is anteversion, anteflexion, retroversion, and retroflection.
Anteversion means that the whole uterus (cervix and fundus) is leaning forward, over the top of the urinary bladder. Contrary, retroversion means that the uterus leans away from the bladder, towards the rectum. This does not necessarily lead to problems in women’s life since it only represents variation in position without the change in the uterine structure.
The third term that appears describing the position of uterus along with anteversion and retroversion is mid-pose, meaning that the uterus doesn’t lean. It stands up, exactly between the urinary bladder and the rectum.
It is estimated that approximately 50% of women have an anteverted uterus, although severity and the degree of this variation may vary. In most cases normal reproductive function is not at risk.
Why Is This Happening?
Movement Of Organs
Although there is not a concise explanation to this question, doctors specify it has a lot to do with the anatomy and the type of the body. There is a lot of space inside the pelvis allowing the organs to shift their position rubbing against one another which can result in impair uterine placement and its axis.
In most cases girls are born with a midposed uterus, which during the growth and development tilts to one side. Pressure from a growing bladder more often causes the uterus to lean forward. The anteverted position of the uterus occurs more often in comparison to retroverted, which is caused by the pulling of the uterus from the rectum.
Pregnancy and childbirth may also be the reason for the uterus to lean towards the urinary bladder. During the pregnancy, thick uterine muscle wall stretches and grows multiple times, allowing the growth of the baby. This growth combined with the position of the baby can cause tipping of the uterus. Great physical intensity and pressure provoked during the birth may cause ligament holding the uterus in the position, to weaken. This may result in leaning forward.
All the changes in the uterus and the surrounding pelvic structures, caused by the pregnancy and process of giving birth, may resolve and the uterus may come back to its natural state. However, in some women these changes remain for good. During the physiological process of aging all tissues in the body become softer and weaker. Same is with the uterine muscles and the ligaments keeping it in place, resulting in position shift. This shift is even more expressed in women in which postpartum changes did not resolve, leading to even more tilting.
The Question Of Fertility
We are naturally not aware of the position of our internal organs. The same applies to the position of the uterus. In most cases, women do not know they have developed forward tipped uterus. The anteverted uterus is most often considered just as a biological change of the organ positioning and has nothing to do with the fertility of the woman or with her general sexual health. In order for pregnancy to happen, spermatozoids have to pass the uterine cavity and reach Fallopian tubes. There is no evidence assuming that this process is dependent on the manner in wich uterus is placed.
When extreme leaning of the uterus occurs it may cause discomfort which is especially expressed in the late stages of the pregnancy. The gynecologist should easily diagnose this state during an ultrasound or other routine checkups. This state can sometimes be related to the miscarriage and serious problems during childbirth, but usually, it is not related to major problems.
Data collected during regular check-ups and ultrasound examinations are very helpful to the doctor leading the pregnancy in order to plan a further course of pregnancy and other needed procedures.
Every problem or disorder during the pregnancy is indicated that medical help is needed. However, when diagnosed with anteverted uterus it is not necessarily something to worry about, while it is a rare cause of problems with fertility or general health. Most often it is just a physiological variation.
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