A unicornuate uterus represents a uterine malformation where the uterus is formed from one only of the paired

Müllerian duct Paramesonephric ducts (or Müllerian ducts) are paired ducts of the embryo that run down the lateral sides of the genital ridge and terminate at the sinus tubercle in the primitive urogenital sinus. In the female, they will develop to form the fal ...

s while the other Müllerian duct does not develop or only in a rudimentary fashion. The sometimes called ''hemi-uterus'' has a single horn linked to the ipsilateral

fallopian tube The fallopian tubes, also known as uterine tubes, oviducts or salpinges (singular salpinx), are paired tubes in the human female that stretch from the uterus to the ovaries. The fallopian tubes are part of the female reproductive system. In o ...

that faces its

ovary The ovary is an organ in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary () found on each side of the body. ...

Signs and symptoms

Women with the condition may be asymptomatic and unaware of having a unicornuate uterus; normal pregnancy may occur. In a review of the literature Reichman et al. analyzed the data on pregnancy outcome of 290 women with a unicornuate uterus. 175 women had conceived for a total of 468 pregnancies. They found that about 50% of patients delivered a live baby. The rates for ectopic pregnancy was 2.7%, for miscarriage 34%, and for preterm delivery 20%, while the intrauterine demise rate was 10%. Thus patients with a unicornuate uterus are at a higher risk for pregnancy loss and obstetrical complications.

Cause

The uterus is normally formed during

embryogenesis An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male spe ...

by the fusion of the two

s. If one of the ducts does not develop, only one Müllerian duct contributes to the uterine development. This uterus may or may not be connected to Müllerian structure on the opposite site if the Müllerian duct on that site undergoes some development. A unicornuate uterus has a single cervix and vagina. Associated defects may affect the renal system, and less common, the

skeleton A skeleton is the structural frame that supports the body of an animal. There are several types of skeletons, including the exoskeleton, which is the stable outer shell of an organism, the endoskeleton, which forms the support structure inside ...

. The condition is much less common than these other uterine malformations: arcuate uterus, septate uterus, and bicornuate uterus. While the uterus didelphys is estimated to occur in 1/3,000 women, the unicornuate uterus appears to be even more infrequent with an estimated occurrence of about 1/4,000.

Diagnosis

A pelvic examination will typically reveal a single vagina and a single cervix. Investigations are usually prompted on the basis of reproductive problems. Helpful techniques to investigate the uterine structure are

transvaginal ultrasonography Vaginal ultrasonography is a medical ultrasonography that applies an ultrasound transducer (or "probe") in the vagina to visualize organs within the pelvic cavity. It is also called transvaginal ultrasonography because the ultrasound waves go ' ...

and sonohysterography, hysterosalpingography, MRI, and hysteroscopy. More recently 3-D ultrasonography has been advocated as an excellent non-invasive method to evaluate uterine malformations.

Rudimentary horn

A unicornuate uterus may be associated with a rudimentary horn on the opposite site. This horn may be communicating with the uterus, and linked to the ispilateral tube. Occasionally a pregnancy may implant into such a horn setting up a dangerous situation as such pregnancy can lead to a potentially fatal uterine rupture. Surgical resection of the horn is indicated.

Management

Patients with a unicornuate uterus may need special attention during pregnancy as

miscarriage Miscarriage, also known in medical terms as a spontaneous abortion and pregnancy loss, is the death of an embryo or fetus before it is able to survive independently. Miscarriage before 6 weeks of gestation is defined by ESHRE as biochemica ...

, fetal demise,

premature birth Preterm birth, also known as premature birth, is the birth of a baby at fewer than 37 weeks gestational age, as opposed to full-term delivery at approximately 40 weeks. Extreme preterm is less than 28 weeks, very early preterm birth is between ...

, and malpresentation are more common. It is unproven that cerclage procedures are helpful. A pregnancy in a rudimentary horn cannot be saved and needs to be removed with the horn to prevent a potentially fatal rupture of the horn and uterus. Although it is unclear whether interventions before conception or early in pregnancy such as resection of the rudimentary horn and prophylactic cervical cerclage decidedly improve obstetrical outcomes, current practice suggests that such interventions may be helpful.

References

External links

{{DEFAULTSORT:Unicornuate Uterus Anatomical pathology Congenital malformations of uterus and cervix