Mullerian Duct

Definition - What does Mullerian Duct mean?

The müllerian ducts are a pair of tubes (ducts) in a developing fetus that fuse together to become the uterus, cervix, fallopian tubes and the upper end of the vagina. Complete fusion results in a normal, single uterine cavity.

The parallel male duct system is called the Wolffian duct.

Congenital (from birth) uterine anomalies can result from a defect in the fusion of the müllerian ducts and can be the cause of infertility or miscarriages, preterm births, and difficult childbirth.

A müllerian duct may also be called a paramesonephric duct.

FertilitySmarts explains Mullerian Duct

The development of the müllerian ducts begins at about the fourth week of life. During normal development, these ducts come together side by side and there is a fusing of the two ducts. This leads to the formation of a single uterus with an open cavity and two fallopian tubes.

However, in certain cases the uterus and fallopian tubes may not form normally. These malformations are called müllerian duct anomalies (MDA).

The range of these defects is wide, and on one end of the spectrum, the defects may go unnoticed, at the other end müllerian anomalies may make it difficult or impossible to become pregnant.

The extent of difficulty depends on the kind or extent of a fusion disorder.

Common types of müllerian anomalies include:

  • Müllerian agenesis, where the fallopian tubes and uterus fail to form.
  • Uterine didelphys, which is a complete duplication with two uteri, cervices, and vaginas.
  • Unicornuate uterus, when one duct underdevelops and a half-uterus forms.
  • Bicornuate uterus, where the uterus has an indentation at the top and takes on a heart shape, leaving less space for a developing fetus.
  • Septate uterus, where a piece of tissue divides the uterus. Known as a uterine septum, this can typically be surgically removed.
  • Arcuate uterus, in which there is a slight indentation on the top of the uterus and can be considered a variation of normal.

Women with fusion disorders are more likely to have miscarriages and preterm births. When pregnancy goes to full term, the position of the baby at birth may not be correct, making it difficult for normal passage of the baby through the birth canal.

Fusion disorders can be diagnosed through ultrasound, magnetic resonance imaging (MRI) or a surgical procedure.

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