Causes and Diagnoses

Causes and Diagnoses of Congenital Anomalies of the Bladder and Genitalia

The exact cause of congenital GU anomalies is not completely understood. However, we do know that most anomalies of the reproductive system occur during the eighth week of development and are likely due to the arrest of development of the preliminary structures. The development of the genito-urinary system begins during the third week in pregnancy and carries into the second trimester. The formation of the reproductive tract is closely associated with the development of the urinary system, which is why women with anomalies of the reproductive system commonly have anomalies of the renal system. Some of the anomalies of the urinary tract and kidney have been shown to be associated with diabetes in pregnancy.

How common are anomalies of the genital and urinary system?

Anomalies of the genital system affect a little over 5 percent of women. Congenital anomalies of the kidneys and urinary tract (CAKUT) affect 4 in 1000 births.

What are some common anomalies of the vagina/hymen?

• Anomalies of hymen: The hymenal membrane consists of connective tissue attached to the vaginal wall. Variations can occur when there is loss of central degradation of the hymen during development. This results in the presence of “excess” hymenal tissue that can block the opening of the vagina. Depending on the variation, the hymen can be completely imperforate (covering the entire opening to the vagina) or partially imperforate (only covering a portion of the vaginal opening).
• Anomalies of the vagina: Septa are common vaginal anomalies in which there is extra tissue within the vaginal canal. Septa can be oriented either horizontally in the vagina, as in “transverse vaginal septum,” or vertically in the vagina, called “longitudinal vaginal septum.” These septa arise from different variations in the embryologic development of the vagina and also can cause varying degrees of symptoms. They are each associated with different types of “co-variations” of development. Notably, transverse vaginal septa are associated with a higher risk of renal anomalies, and longitudinal septa are associated with uterine anomalies.
• Vaginal agenesis (absence of a vagina): Absence of a vagina is a rare variation in development. Typically, girls are diagnosed in adolescence when they present to a doctor with the absence of a period. This is also associated with various anomalies affecting the uterus, most commonly, absence of a uterus. Notably, ovaries are typically normal with this type of variation.

What are some anomalies of the uterus?

Defects involving the uterus are commonly referred to as “Müllerian” anomalies. They result from variations in the Müllerian tubes, the “progenitors” to the female reproductive system. As such, the different types of uterine anomalies are often grouped with respect to their corresponding variation in the development of the Müllerian system. Common examples include bicornuate uretus, unicornuate uterus, arcuate uterus, and didelphys uterus.

What are some common congenital anomalies of the urinary tract?

• Vesicoureteral reflux: Vesicoureteral reflux is a condition in which the ureters are structurally abnormal and allow for urine to travel backwards (toward the kidney) which is known as reflux. This can cause an increased risk of urinary tract infections and might require repair in childhood to prevent renal damage.
• Ectopic ureters: Ectopic ureters refer to the abnormal orientation of the ureteral orifice (or opening). Sometimes the location of the orifice is within the bladder or urethra, or it can be located in the vagina.
• Duplicated ureters: Complete or partial duplication of the urinary collecting system is the most common anomaly of the urinary tract, affecting 2–4 percent of the population.
• Bladder exstrophy: This is a rare anomaly in which the bladder is exteriorized to the abdominal wall. The severity of this anomaly typically requires immediate surgical intervention in infancy. Women born with this anomaly often have normal reproductive potential but require a high level of supervision during pregnancy and delivery.
• Disorders of sexual development (DSD): These are conditions in which the appearance of the external genitalia appear neither distinctly female or male and are instead termed, “ambiguous.” Sometimes associated systemic manifestations are present which require immediate evaluation and intervention. However, slight variations in anatomy may not warrant evaluation until adolescence. The most common types of DSD are:
• Androgen insensitivity syndrome (AIS): An inherited condition in which the body’s cells are unable to respond to male hormones. In this condition, the external appearance is either female or ambiguous, although the patient is genetically male.
• Partial androgen insensitivity syndrome (PAIS): This condition is similar to AIS, but often the child is less severely affected, and the genital appearance is typically ambiguous.
• Congenital adrenal hyperplasia (CAH): A condition in which the adrenal gland is unable to properly synthesize steroids, leading to an increase in “male” hormones. There are many variations of this condition, but commonly this is seen in a genetically female infant who appears to have “masculine” external genitalia. Some infants with CAH may also have a potentially life threatening inability to regulate salt and water.