We all know that the uterus is one of the vital parts of the female reproductive system. In normal cases, the uterus that is located in the pelvis is found as a pear-shaped organ which is approximately 7.5 cm in length, 5 cm in width and 2.5 cm in depth. This hollow organ with thick muscular walls has an upper part called the fundus or body and the lower narrower part called cervix that opens to the vagina. However, the structure and size of the uterus may differ in some females. In some cases, variations in the structure may amount to malformations, which in turn may affect pregnancy. Such a type of malformed uterus is termed unicornuate uterus, which may be a risk factor, as far as pregnancy is concerned.
What is a Unicornuate Uterus
As mentioned above, the uterus may be malformed in some women. Such uterine malformations can be of different types. They include unicornuate uterus, bicornuate uterus, septate uterus, uterus didelphys and arcuate uterus. The uterus is an organ that is formed during the fetal stage, through fusion of the two pairs of mullerian ducts. If one of the mullerian duct pairs fails to develop during the embryonic stage or if it does not develop properly, the result will be a unicornuate uterus. If there is a second pair of mullerian ducts that is not properly developed, it will appear as a rudimentary structure along with the unicornuate uterus. This structure is referred to as a rudimentary horn, which is found on the opposite side of the uterus.
So, a unicornuate uterus will be almost half the size of a normal uterus. In general, such a uterus is found to have one working fallopian tube, a single cervix and vagina. This type of uterine malformation is found to be very uncommon and as per statistics, this condition is seen in one among every 4000 females. It is also said that unicornuate uterus is rare, as compared to other types of uterus malformations. Only 10 percent of the women with uterine abnormalities are diagnosed with such uterus.
Unicornuate Uterus and Pregnancy Risks
This type of uterus may not cause any symptom, till the female gets pregnant or develops problems in conceiving. If there is a rudimentary horn, the woman may develop certain symptoms like immense pain during periods. However, the main problem will be difficulty in getting pregnant and to maintain the pregnancy to the full term. Pregnancy can be a risky affair for those with a unicornuate uterus. The most common risks are that of an ectopic pregnancy, spontaneous miscarriage, preterm childbirth and fetal death. In those women with this type of uterine malformation, the chances of delivering a live baby is said to be around 50 percent.
According to a study conducted by some health experts, those with a unicornuate uterus have a 2.7% chance of an ectopic pregnancy, around 30% chance of a miscarriage, 20% chance of a preterm delivery, and 10% chance of fetal death. In short, such a uterus is risky, as far as pregnancy and childbirth is concerned.
The risk of ectopic pregnancy in a unicornuate uterus is believed to be due to problems with blood supply to the organ. Such abnormal blood supply may either affect the placental functioning or increase the chance of implantation of the embryo inside the fallopian tube itself. It could be the limited space inside this type of uterus that triggers a miscarriage. It has also been observed that women with a malformed uterus are likely to have a weak cervix, which is another risk factor for pregnancy.
In case of presence of a rudimentary horn that is connected the uterus, there are chances that the embryo gets implanted inside this structure that may rupture as the embryo grows. This is another risk factor, as far as a unicornuate uterus and pregnancy is concerned. However, there are instances of successful completion of the pregnancy term and delivery in some women with unicornuate uterus. You may also come across women with this type of uterine malformation opting for second and third pregnancies.
To conclude, a unicornuate uterus may pose problems with conception and delivery. There is no treatment to correct this condition, as the size of the uterus cannot be increased. But, in case the rudimentary horn is causing severe pain during periods, it can be removed surgically. Such surgery to remove the rudimentary structure is unavoidable if the implantation happens inside it. For those with a weak cervix, cervical cerclage may be recommended. Others must take enough care to complete the term of pregnancy. This must be done as per the instructions of the gynecologist.