In a female fetus, the uterus starts out as two small tubes. As the fetus develops, the tubes normally join to create one larger, hollow organ — the uterus. Sometimes, however, the tubes don't join completely. Instead, each one develops into a separate structure. This condition is called double uterus (uterus didelphys). A double uterus may have one opening (cervix) into one vagina, or each uterine cavity may have a cervix. There may even be two vaginas.
Double uterus is rare — and sometimes never diagnosed. The percentage of women with a double uterus is likely higher in those with a history of miscarriage or premature birth.
Treatment is needed only if a double uterus causes symptoms or complications, such as pelvic pain, repeated miscarriages or preterm labor.