The arcuate uterus is a form of a uterine anomaly or variation where the uterine

Uterus

The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...

 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 septation. The distinction between an arcuate uterus and a septate uterus is not standardized.

Etiology

The uterus is formed during embryogenesis

Embryogenesis

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 mullerian 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. During this fusion a resorption process eliminates the partition between the two ducts to create a single cavity. This process begins caudally and advances cranially, thus an arcuate uterus represents an in the final stage incomplete absorption process.

Prevalence

Most studies of uterine malformation

Uterine malformation

A uterine malformation is a type of female genital malformation resulting from an abnormal development of the Müllerian duct during embryogenesis...

s are based on populations of women who have experienced a pregnancy loss and thus do not address the issue of the prevalence in the general population. A screening study by Woelfer at al. of women without a history of reproductive problems found that about 5% of women had an arcuate uterus when they defined an arcuate uterus any fundal protrusion into the cavity that had an apical angle of more than 90 degrees. Accodingly it was the most common uterine anomaly, followed by uterine septum (3%) 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....

 (0.5%).

Clinical presentation

The condition may not be known to the affected individual and not result in any reproductive problems; thus normal pregnancies occur. Indeed, there is no consensus on the relationship of the arcuate uterus and recurrent pregnancy loss. Accordingly, the condition may be a variation or a pathology.

One view maintains that the condition is associated with a higher risk for miscarriage

Miscarriage

Miscarriage or spontaneous abortion is the spontaneous end of a pregnancy at a stage where the embryo or fetus is incapable of surviving independently, generally defined in humans at prior to 20 weeks of gestation...

, premature birth

Premature 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. Thus a study that evaluated women with uterine bleeding by hysteroscopy found that 6.5 % of subjects displayed the arcuate uterus and had evidence of reproductive impairments. A study based on hysterosalpingraphic detected arcuate lesions documented increased fetal loss and obstetrical complications as a risk for affected women. Woelfer found that the miscarriage risk is more pronounced in the second trimester. In contrast, a study utilizing 3-D ultrasonography to document the prevalence of the arcuate uterus in a gynecological population found no evidnce of increased risk of reproductive loss; in this study 3.1% of women had an arcuate uterus making it the most common uterine anomaly; this prevalence was similar than in women undergoing sterilization and lower than in women with recurrent pregnancy loss.

Diagnosis

A pelvic examination will not reveal the condition. 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 delineate the condition.

Management

Many patients with an arcuate uterus will not experience any reproductive problems and do not require any surgery. In patients with recurrent pregnancy loss thought to be caused by an arcuate uterus hysteroscopic resection can be performed.

Differential diagnosis

The major differential diagnosis is the uterine septum. The lack of agreement to separate these two entities makes it difficult to assess the results in the literature.