AUA Summit - What is Vaginal Fusion and Duplication?


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What is Vaginal Fusion and Duplication?

How do the female reproductive organs work?

There are many functions of the female reproductive system. The ovaries make female egg cells, called ova or oocytes. The oocytes move down the fallopian tube where an egg may get fertilized by a sperm. The fertilized egg then moves to the uterus, where the uterine lining has gotten thicker. The lining has gotten thicker in response to the normal hormones of the reproductive cycle. The fertilized egg can implant into thickened uterine lining and continues to develop. If fertilization does not take place, the uterine lining is shed as menstrual flow.

In addition to making egg cells, ovaries produce female sex hormones, estrogen and progesterone, that maintain the reproductive cycle.

How do genitalia normally form?

At conception, the mother gives an X chromosome and the father an X or Y chromosome. This combination forms a female embryo (XX), or a male embryo (XY). Early in pregnancy, the male and female embryo’s inner and outer reproductive structures (genitals) look the same. Over time, the male embryo will develop testes (testicles) and the female embryo will form ovaries. These will secrete hormones that stimulate the “indifferent” genitals to form female or male structures. The vagina is one of the reproductive organs to develop first.

The fallopian tubes, uterus and upper and mid vagina come from two Mullerian ducts, one on the right and one on the left. The lower Mullerian structures join together (fuse) in the midline to form one uterus and one vagina.

Sometimes the fusion of the Mullerian structures does not occur normally producing “fusion” abnormalities, also call “duplication”.

  • In uterus didelphys, there are two each of a (hemi) duterus, cervix and vagina. Usually one vagina is blocked, and the other is unblocked.
  • In uterus duplex bicollis, there are two uteruses and cervices, but only one vagina.
  • In bicornate uterus, there are two uteruses fused at the bottom with one cervix and one vagina.


There may be no clear signs. Often the outer organs may not look normal.

In adult women, infertility is the main problem.

For a baby or young girl, early signs of this disease could be:

  • Urine pooling then leaking from the vagina during and after passing urine
  • Frequent urinary tract infections (UTI)
  • A lump or mass in the lower belly
  • Discomfort with puberty


Some fusion abnormalities can be seen in newborns. Lumps in the lower belly, found with a physical exam may signal this problem. An ultrasound can show why a lump pushes the bladder forward and the vagina back.

Some patients with complete duplication and a block are found at puberty. A girl can get her period, but she will feel discomfort. At that time a lump in the lower belly can be seen. This lump is from the buildup of menstrual fluid in the blocked vagina.

Usually, an ultrasound or MRI is used to make the diagnosis. A surgeon may have to examine your child with endoscopy to look inside the vagina.


Not everyone needs treatment. Each woman should be treated based on her well-being and pregnancy goals.

Surgery is needed to treat vaginal fusion and duplication when:

  • The condition is causing symptoms
  • A woman is unable to get pregnant
  • A woman has had miscarriages

Surgical treatment can let a woman have a healthy pregnancy. If there is complete duplication with blockage, a urologic surgeon may need to drain fluid or correct the blockage with surgery.

Updated March 2024. 

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