Double Reproductive Organs
A couple of years ago an episode of the popular TV series Grey's Anatomy featured a woman with two uteruses (or uteri). This unusual condition does, in fact, occur as a result of abnormal fetal development. It has made the news again and it appears that a woman in Utah has two uteruses and is carrying a baby in each one.
The Mullerian ducts are two structures present in every embryo. During the ninth week of pregnancy, these structures fuse. While they largely disappear in males, the fused Mullerian ducts develop into the uterus, Fallopian tubes, and vagina in females. If this development does not proceed normally, abnormalities can occur in the genital tract that are often referred to as "fusion" or "duplication" abnormalities.
In women, abnormal development of the Mullerian ducts can lead to a condition known as uterus didelphys, in which the woman has a double set of reproductive tract organs - two each of the uterus, cervix, and vagina. In this case, one vaginal opening is usually blocked and the external appearance of the genitalia is normal.
Another condition known as uterus duplex bicollis occurs when a woman has two each of the uterus and cervix, but only one vagina. If there is doubling of the uterus but only one cervix and vagina, the condition is termed bicornuate uterus. It is also possible to have abnormal development in only one of the two Mullerian ducts, which can lead to an abnormality called unicornuate uterus , with only one normal Fallopian tube.