Unicornuate uterus
Encyclopedia
A unicornuate uterus represents a uterine malformation
where the uterus is formed from one only of the paired Müllerian duct
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
that faces its ovary
.
by the fusion of the two Müllerian duct
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
.
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.
Helpful techniques to investigate the uterine structure are transvaginal ultrasonography and sonohysterography, hysterosalpingography
, MRI, and hysteroscopy
. More recently 3-D ultrasonography has been advocated as an excellent non-invasive method to evaluate uterine malformations.
, 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
Uterine malformation
A uterine malformation is a type of female genital malformation resulting from an abnormal development of the Müllerian duct during embryogenesis...
where the uterus is formed from one only of the paired Müllerian duct
Müllerian duct
Müllerian ducts are paired ducts of the embryo that run down the lateral sides of the urogenital ridge and terminate at the Müllerian eminence in the primitive urogenital sinus. In the female, they will develop to form the Fallopian tubes, uterus, cervix, and the upper two-third of the vagina; in...
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
Fallopian tube
The Fallopian tubes, also known as oviducts, uterine tubes, and salpinges are two very fine tubes lined with ciliated epithelia, leading from the ovaries of female mammals into the uterus, via the utero-tubal junction...
that faces its ovary
Ovary
The ovary is an ovum-producing reproductive organ, often found in pairs as part of the vertebrate female reproductive system. Ovaries in anatomically female individuals are analogous to testes in anatomically male individuals, in that they are both gonads and endocrine glands.-Human anatomy:Ovaries...
.
Etiology
The uterus is normally formed during embryogenesisEmbryogenesis
Embryogenesis is the process by which the embryo is formed and develops, until it develops into a fetus.Embryogenesis starts with the fertilization of the ovum by sperm. The fertilized ovum is referred to as a zygote...
by the fusion of the two Müllerian duct
Müllerian duct
Müllerian ducts are paired ducts of the embryo that run down the lateral sides of the urogenital ridge and terminate at the Müllerian eminence in the primitive urogenital sinus. In the female, they will develop to form the Fallopian tubes, uterus, cervix, and the upper two-third of the vagina; in...
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
Skeleton
The skeleton is the body part that forms the supporting structure of an organism. There are two different skeletal types: the exoskeleton, which is the stable outer shell of an organism, and the endoskeleton, which forms the support structure inside the body.In a figurative sense, skeleton can...
.
The condition is much less common than these other uterine malformations: arcuate uterus
Arcuate uterus
The arcuate uterus is a form of a uterine anomaly or variation where the uterine fundus displays a concave contour towards the uterine cavity. Normally the fundus of the uterus is straight or convex on anterior-posterior imaging but in the arcuate uterus it dips into the cavity and may form a small...
, septate uterus, and bicornuate uterus
Bicornuate uterus
A bicornuate uterus or bicornate uterus, commonly referred to as a "heart-shaped" uterus, is a type of uterine malformation where two "horns" form at the upper part of the uterus.-Pathophysiology:A bicornuate uterus is formed during embryogenesis....
. 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.
Presentation
Women with the condition may be asymptomatic and unaware of having a uniconuate 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.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.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 and sonohysterography, hysterosalpingography
Hysterosalpingography
Hysterosalpingography is a radiologic procedure to investigate the shape of the uterine cavity and the shape and patency of the fallopian tubes. It entails the injection of a radio-opaque material into the cervical canal and usually fluoroscopy with image intensification...
, MRI, and hysteroscopy
Hysteroscopy
Hysteroscopy is the inspection of the uterine cavity by endoscopy with access through the cervix. It allows for the diagnosis of intrauterine pathology and serves as a method for surgical intervention .-Method:...
. More recently 3-D ultrasonography has been advocated as an excellent non-invasive method to evaluate uterine malformations.
Management
Patients with a unicornuate uterus may need special attention during pregnancy as pregnancy loss, fetal demise, premature birthPremature birth
In humans preterm birth refers to the birth of a baby of less than 37 weeks gestational age. The cause for preterm birth is in many situations elusive and unknown; many factors appear to be associated with the development of preterm birth, making the reduction of preterm birth a challenging...
, 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