The Meaning of a Tipped Uterus
“I was told that I had a tipped uterus – what does that mean?” – A common question or concern is the meaning of a “tipped” uterus. In order to understand the significance of this finding we need to take a step back and look at normal female anatomy. When a woman is lying flat on her back, the vagina normally slopes slightly downward from the outside vaginal opening (introitus) to the cervix. In most women the uterus lies at a right angle to the vagina and is normally “tipped” forward (antiverted) or “tipped” backward (retroverted). This antiverted or retroverted position allows the uterus to lie on, and be supported by, a sling of muscle and connective tissue that is tethered to either side of the bones of the pelvis. Thus, for most women, their uterus is in fact “tipped” with the most common position being antiverted (64-74%) followed by 15-25% that are retroverted and about 5-10% where the uterus is more or less lined up with the axis of the vagina (axial). In addition to the lie of the uterus, it is also commonly flexed either forward or backward (antiflexed or retroflexed) at the junction of the upper part of the uterus (fundus) with the cervix. Lastly, for the majority of women, the uterus is deviated to her right side, largely due to the presence of the sigmoid colon as it traverses down the left side of the abdomen towards the rectum.
The orientation of the uterus is largely genetic and it does tend to run in families. The position of the uterus is usually established by a pelvic exam or by a vaginal or abdominal ultrasound. There are conditions such as the presence of large fibroids, endometriosis, or previous pelvic infection or scar tissue that may convert an antiverted uterus to a retroverted position. For some women, especially those who have had a vaginal delivery, the uterus can be seen to “flip” from an antiverted to retroverted position depending on the placement of the vaginal ultrasound probe.
So what is the significance of the position of the uterus? If the uterus is either sharply antiverted or retroverted, it will cause the cervix to point respectively very posteriorly (backward) or anteriorly (forward) making a pelvic speculum exam, where access to the cervix is required (e.g. completing a pap smear, insemination or embryo transfer), more difficult and uncomfortable. Pregnancy rates are not affected by the position of the uterus, either naturally or through assisted reproductive technologies (ART) of insemination (IUI) or in vitro fertilization (IVF). Since abdominal ultrasound is often used to guide catheter placement for an embryo transfer, visualization of a retroverted uterus may be more challenging, but again, in no way does it impact pregnancy rates. In pregnancy, the retroverted uterus will almost always resolve spontaneously progressing entirely by 14 weeks gestation as it grows up into the abdomen. For 1 in 3000 women, the retroverted uterus does not make this normal pregnancy transition, but rather gets trapped in the pelvis, growing backward toward the rectum. This is referred to as a trapped or incarcerated uterus and most women with this condition will present with pain and difficulty with bowel movements or urination early in the second trimester of pregnancy. Fortunately, this can usually be easily resolved with either manual or operative intervention and will often require the placement of a pessary to maintain an appropriate position.
There are some isolated reports that having a retroverted uterus may increase the risk for uterine prolapse later in life. This remains somewhat controversial as the evidence for this association is spotty at best. One theory for this association is that since the retroverted uterus is more in line with the vaginal axis, it has less support and is more vulnerable to abdominal, exertional “pushing” forces.
In summary, a “tipped” uterus is really a “normal” position of the uterus and has no bearing on a woman’s ability to conceive. Health care providers will often remark to a patient that her uterus is “tipped”. As the most common, “normal” position is antiverted, this remark is often referring to the fact that the uterus is retroverted.
Sakhel, K., Sinkovskaya, E., Horton, S., Beydoun, H., Chauhan, S. P., and Abuhamad, A. Z. Orientation of the uterine fundus in reference to the longitudinal axis of the body: a 3-dimensional sonographic study. J Ultrasound Med. 33(2), 323-328. 2014.
Egbase, P. E., Al-Sharhan, M., and Grudzinskas, J. G. Influence of position and length of uterus on implantation and clinical pregnancy rates in IVF and embryo transfer treatment cycles. Hum.Reprod. 15(9), 1943-1946. 2000.
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