Table of Contents
The mullerian ducts give origin to the female reproductive tract. The fallopian tubes, uterus, cervix, and superior aspect of the vagina originate from the mullerian ducts; therefore, mullerian duct anomalies can present with a wide range of anatomical disruptions of any of these female reproductive organs.
In addition to fallopian tubes, uterus, cervix and vaginal anomalies, mullerian duct anomalies are also associated with renal and axial skeletal malformations. Patients with mullerian duct anomalies usually have normal looking external genitalia and functional ovaries.
Mayer-Rokitansky-Kuster-Hauser (MRKH) syndrome is a special form of mullerian duct
anomalies that are characterized by the absence of the proximal two thirds of the vagina in addition to vertebral, cardiac, urologic and otologic anomalies. Fertility and pregnancy might be achievable in women with MRKH syndrome with assisted fertility techniques.
Epidemiology of Mullerian Duct Anomalies
The exact incidence or prevalence of mullerian duct anomalies in the general population is unknown, but estimates of the incidence give a figure that is around 0.1 to 3.5%. Other studies that focused on uterine malformations alone reported an estimated incidence of 4.3%.
The incidence of uterine malformations is dependent on the studied population. For instance, women with fertility problems have an estimated incidence of uterine malformations that is around 6%. On the other hand, the incidence of mullerian duct defects can be as high as 10% in women with recurrent abortions.
The estimated prevalence of mullerian duct anomalies ranges between 2 to 10% depending on the studied population. The most commonly identified forms of mullerian duct anomalies are septate, arcuate, didelphys, unicronuate, and hypoplastic uteri.
Pathogenesis of Mullerian Duct Anomalies
These defects are thought to result from a disruption in the normal development of the mullerian ducts in the female. At 6 weeks of development, the mullerian ducts and the Wolffian ducts form. These two duct systems are identical at this stage. If the sex of the fetus is a female, Wolffian ducts undergo degeneration and differentiation of the mullerian ducts start. Disruption of this differentiation process that also involves fusion of different structures is responsible for the defects one can see in mullerian duct anomalies.
A family history of mullerian duct anomalies, exposure to diethylstilbestrol, thalidomide and other intrauterine or extrauterine insults are the most commonly identified causes of mullerian duct defects. A genetic predisposition to mullerian duct anomalies has been documented before and different forms of inheritance that are autosomal dominant, autosomal recessive or x-linked have been described.
Based on the affected parts and the time of the insult, different forms of mullerian duct anomalies can occur. The following table summarizes the classes of mullerian duct anomalies and the description of the anomaly:
|I||The most common example for this class of mullerian duct anomalies is MRKH syndrome. Malformations of the cervix, uterine fundus or fallopian tubes are also common in this class.|
|II||This class donates the presence of a horn in the uterus that can be communicating with the uterine cavity or can be non-communicating. All patients with class II mullerian duct anomalies also have ipsilateral renal and ureter agenesis. The malformation is described as a unicornuate uterus with or without a horn.|
|III||This class of malformations is known as a didelphys uterus and is characterized by the complete or partial duplication of one of the female reproductive organs that originate from the mullerian ducts, i.e. vagina, cervix or uterus.|
|IV||This malformation is known as a bicornuate uterus which can be complete or partial. A septum separates the uterus into two chambers. The septum does not extend to the cervix or the vagina. The septum in this case extends from the uterine fundus to the cervical os.|
|V||This class is characterized by a complete or partial midline septum within the uterus and is known as a septate uterus.|
|VI||This malformation is characterized by a small septate indentation at the fundus of the uterus.|
|VII||This special class of mullerian duct malformations is known as diethylstilbestrol-related abnormalities. A T-shaped uterus which might be associated with horns is the most common pathology.|
Clinical Presentation of Mullerian Duct Anomalies
The most common presentation of mullerian duct anomalies in women is primary amenorrhea. Cyclic abdominal pain can be also present. Patients usually have normal secondary sexual development characteristics and they are phenotypically females. Infertility is another common presentation and recurrent abortions might be the only presentation of a mullerian duct anomaly in an adult female. Patients with abnormal vaginas can present with difficulty with intercourse.
Diagnostic Workup for Mullerian Duct Anomalies
Patients presenting with any of the previously mentioned complaints usually undergo abdominal and pelvic ultrasonographical examination for the structural evaluation of the vagina, cervix, uterus, fallopian tubes and ovaries. In more complicated cases, the patient might need a magnetic resonance imaging study to better visualize the different organs known to be involved in mullerian duct anomalies.
Laboratory investigations in patients with mullerian duct anomalies usually show normal follicle-stimulating hormone and luteinizing hormone levels. Testosterone levels are also normal in females with mullerian duct anomalies. Chromosomal studies and testing for androgen insensitivity syndrome is also indicated.
Treatment of Mullerian Duct Anomalies
Isolated vaginal agenesis is usually repaired surgically with a simple vaginoplasty procedure. A stent might be placed within the new created space to ensure patency after healing. Skin grafting can be used to provide tissue for the vaginoplasty.
Artificial dermis and absorbable adhesion barriers can be also used in vaginal reconstruction procedures with excellent results. A bowel segment can be also used instead of the skin graft for the reconstruction of the vaginal cavity.
Surgical treatment of class-II mullerian duct anomalies should be reserved for patients with rudimentary horns that have an endometrium. Laparoscopic excision of the horn can be done easily and with excellent results. Surgical interventions with bipolar coagulation of the pedicle of the horn can be also used to remove the accessory horn.
Patients with class-III malformations usually present late compared to other forms of mullerian duct anomalies. Surgical intervention is dependent on whether the duplicate uterus is obstructed with a unilateral vagina or non-obstructed.
Patients with a non-obstructed uterus didelphys should undergo the Strassmann metroplasty procedure where the two uterine cavities are unified and the cervix is left intact. Patients with an obstructed duplicate uterus should undergo a full excision of the vaginal septum in addition to a hemihysterectomy. If a hemihysterectomy is going to be performed, it might be reasonable to remove the ovary and the fallopian tube on that side.
Class-IV malformations can be treated with the excision of the uterine horns, and apposition of the myometrial edges. Class V malformations are best treated with hysteroscopic metroplasty with laparoscopy. The treatment of Class VI malformations is like Class V malformations. Treatment of class VII malformations is dependent on the type and extent of the exact structural abnormalities.