Congenital Structural Abnormalities

Congenital structural abnormalities of the reproductive tract are caused by abnormal development of the pelvic organs prior to birth. This can lead to menstrual, sexual and reproductive problems. These abnormalities may be the result of faulty genes, or occur randomly in otherwise healthy individuals. This section covers some of the key congenital structural abnormalities that you may encounter in your exams and career.  

 

Basic Embryological Development

The upper vaginacervixuterus and fallopian tubes develop from the paramesonephric ducts (Mullerian ducts). These are a pair of passageways along the outside of the urogenital region that fuse and mature to become the uterus, fallopian tubes, cervix and upper third of the vagina. Errors in their development lead to congenital structural abnormalities in the female pelvic organs. In a male fetus, anti-Mullerian hormone is produced, which suppresses the growth of the paramesonephric ducts, causing them to disappear.

TOM TIP: If you remember one thing about the embryology of the female reproductive system, remember the Mullerian ducts. Medical school exams are unlikely to test your knowledge of the embryology of the female reproductive system in detail (unless the exam is specific to that topic). However, they may refer to a congenital structural abnormality and ask what structure in the fetus this relates to. The answer is the Mullerian ducts. Equally, they may ask why males do not develop a uterus, and the answer is anti-Mullerian hormone.

 

Bicornuate Uterus

A bicornuate uterus is where there are two “horns” to the uterus, giving the uterus a heart-shaped appearance. It can be diagnosed on a pelvic ultrasound scan. A bicornuate uterus may be associated with adverse pregnancy outcomes. However, successful pregnancies are generally expected. In most cases, no specific management is required. 

Typical complications include:

  • Miscarriage
  • Premature birth
  • Malpresentation

 

Imperforate Hymen

Imperforate hymen is where the hymen at the entrance of the vagina is fully formed, without an opening. 

Imperforate hymen may be discovered when the girl starts to menstruate, and the menses are sealed in the vagina. This causes cyclical pelvic pain and cramping that would ordinarily be associated with menstruation, but without any vaginal bleeding.

An imperforate hymen can be diagnosed during a clinical examination. Treatment is with surgical incision to create an opening in the hymen.

Theoretically, if an imperforate hymen is not treated retrograde menstruation could occur leading to endometriosis.

 

Transverse Vaginal Septae

Transverse vaginal septae is caused by an error in development, where a septum (wall) forms transversely across the vagina. This septum can either be perforate (with a hole) or imperforate (completely sealed). Where it is perforate, girls will still menstruate, but can have difficulty with intercourse or tampon use. Where it is imperforate, it will present similarly to an imperforate hymen with cyclical pelvic symptoms without menstruation. Vaginal septae can lead to infertility and pregnancy-related complications.

Diagnosis is by examination, ultrasound or MRI. Treatment is with surgical correction. The main complications of surgery are vaginal stenosis and recurrence of the septae.

 

Vaginal Hypoplasia and Agenesis 

Vaginal hypoplasia refers to an abnormally small vagina. Vaginal agenesis refers to an absent vagina. These occur due to failure of the Mullerian ducts to properly develop, and may be associated with an absent uterus and cervix. 

The ovaries are usually unaffected, leading to normal female sex hormones. The exception to this is with androgen insensitivity syndrome, where there are testes rather than ovaries.

Management may involve the use of a vaginal dilator over a prolonged period to create an adequate vaginal size. Alternatively, vaginal surgery may be necessary.

 

Last updated June 2020
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