Abnormally Shaped Uterus as a Cause of Infertility
When a woman’s uterus, or womb, is abnormally shaped before birth (congenital), it can cause obstetric or infertility issues in her reproductive years. These abnormalities can complicate child birth and the child’s health. They can also result in irregular periods or not having any period. According to the March of Dimes, about 3 in 100 women are born with an abnormally shaped uterus.
Many times a woman only finds out about this congenital abnormality when a doctor examines her. The primary types of abnormalities in uterine shape include:
- Bicornuate uterus is partially split so that it has a heart shape. This occurs when the two tubal structures that normally join to form the womb do not unify during fetal development. Bicornuate uterus is sometimes associated with poor obstetric outcomes like miscarriage and preterm labor.
- Septate uterus occurs when the tissue of the residual septum wall is not absorbed into the single uterine cavity, as it is during the normal final stage of development. This results in a septum wall in the center that divides the space into two uterine cavities. This abnormality is associated with recurrent pregnancy loss.
- Unicornuate uterus is when only one side of the womb develops fully, usually with the cervix connected to the vagina. This cannot be corrected and can cause premature delivery and difficulties in childbirth.
- Didelphic uterus, or double uterus, is when a woman has two separate uterine cavities, each having a separate cervix. This type of abnormality has not been shown to be effectively corrected by surgical treatment.
Many women with an abnormally shaped womb do not have problems conceiving or delivering a healthy child. However, some uterine abnormalities benefit from treatment, which is usually by minimally invasive surgical correction.
Other conditions in the uterus can affect fertility, such as uterine fibroids. Sometimes surgery can result in a uterine problem as well. This page only deals with congenital, structural uterine problems.
How the bicornuate uterus and other uterine abnormalities form
An uterine abnormality occurs when the fetus is in the mother’s womb. During development of the female fetus, the Müllerian ducts begin the formation of the female reproductive tract that includes the uterus, fallopian tubes, the cervix and the part of the vagina that connects to the cervix. Malformation during development can result in different types of abnormally shaped uteri and can similarly affect the vagina.
At about 10 weeks into a female fetus’ development, two Müllerian duct tubal structures form side by side and then unify to create the uterine cavity. At that point, there is still a section of a septum wall, which is tissue that is normally eliminated in the final stage of the womb’s development.
An obstructive abnormality can form when the uterus and the vagina have not unified together. This is called a transverse vaginal septum. Such obstructive abnormalities cause the menstrual blood to remain in the uterus and not leave the body through the vagina. This accumulation can cause severe pelvic pain.
Nonobstructive abnormalities include the bicornuate, unicornuate, septate and didelphic uteri mentioned above. These do not prevent the proper outflow of menstrual blood.
Aside from infertility problems from a uterine abnormality, birthing complications and child health issues may arise. These include:
- Breech or other baby positioning problems in the womb.
- Need for Cesarean section birth.
- Premature birth.
- Slower baby growth.
- Birth defects due to restrictions on the fetus’ growth in the womb.
Uterine abnormality symptoms & diagnosis
Most of the time, a uterine abnormality (also called a uterine anomaly or uterine defect) doesn’t cause the woman to experience any symptoms. Discovering an abnormally shaped uterus in these women generally only happens when they get a pelvic exam or ultrasound, either as a routine screening or to determine a cause for possible infertility.
When symptoms do occur from an abnormality, they can include:
- Recurrent miscarriages.
- Not ever having a period.
- Pain: inserting a tampon, during sex, with menstruation.
- Monthly abdominal pain, in the case of an obstructive uterine abnormality.
Diagnosis & treatment
A physician will first do a physical examination, if one hasn’t already been conducted. We generally use different types of diagnostic testing to identify if a woman has an abnormally shaped uterus, what kind it is, and what is the best course of action and treatment. Sometimes we will need to conduct more than one of these tests, which include the following.
- Sonohysterogram (SIS). This involves placement of a catheter into the uterus to allow distention of the uterine cavity with saline. Then while the catheter is inside, a transvaginal ultrasound is performed to visualize the cervix, uterus and ovaries.
- Hysterosalpingogram (HSG). A contrast dye is injected into the cervix and uterus and X-rays are taken of those areas and the fallopian tubes. The dye results in better images of these organs. Sonohysterogram is often used to distinguish between a septate or bicornuate uterus.
- Laparoscopy and/or Hysteroscopy. This uses a thin tube with a camera that’s inserted through very small incisions in the woman’s abdomen or through the vagina and cervix (for the latter procedure) to view into the uterus. The images are relayed to a computer screen. If surgical correction needs to be done, it can be done at this time with special surgical instruments inserted through the tube.
- MRI. A magnetic resonance imaging (MRI) test gives us very good images of the womb and surrounding structures. It is very accurate in diagnosing most uterine abnormality issues.
If these tests result in a diagnosis of an abnormally shaped uterus, the physician will discuss next steps with the patient.
Treatment of an abnormally shaped uterus
Surgery is the only treatment to correct an abnormally shaped uterus, yet many women with such abnormalities don’t need the issue to be surgically corrected. We generally recommend a surgical correction if the woman has had recurrent miscarriages or has compromised fertility due to the uterine abnormality. We may also recommend surgery to correct the issue if she experiences uncomfortable pain regularly.
When appropriate, surgeons will most often perform minimally invasive surgery via laparoscopy or hysteroscopy.
Surgically correcting a septate uterus can improve the chances of a successful pregnancy in a woman with recurrent miscarriages. In the past, surgery could be considered on a bicornuate uterus; however, surgery these days is not the norm for this condition and is reserved mostly for recurrent adverse obstetric outcomes. Additionally, surgical corrections of unicornuate uterus and didelphic uterus have not been shown to be effective treatments at improving pregnancy outcomes.