Urinary system birth defects

The body usually has two kidneys, one on either side of the middle of the back. They filter waste from the blood and produce urine. Some babies are born with differences in how the urinary system has formed.

How the urinary system works#

Urine leaves each kidney through a tube called a ureter and drains into the bladder, where it is stored. The urethra is a tube that carries urine from the bladder to the outside of the body.

Common congenital variations of the urinary system include hypospadias, obstruction of the renal pelvis and renal agenesis.

Hypospadias#

Hypospadias is a variation in how the penis forms. The urethral opening is located on the underside of the penis rather than at the tip, and it may sit anywhere along the shaft, sometimes as far back as the base of the scrotum. It is one of the more common genital variations, occurring in around one in 150 births.

Hypospadias is usually noticed at birth. When it is very mild, it may not be diagnosed until later in life.

Causes#

The causes of hypospadias are not known. There appears to be a genetic link, because a baby boy with a family history of the condition is slightly more likely to be born with it.

Treatment#

Hypospadias does not require urgent surgery. In more severe cases, or when it occurs alongside other findings, further testing helps to check for any related issues.

Surgery, when needed, is most commonly performed between 6 and 18 months of age. The aims are to reposition the urethral opening at the tip of the penis and to straighten the penis if there is downward curvature (chordee). Repositioning the opening is relatively straightforward and can often be done in a single stage in mild cases.

More severe cases may need a two-stage procedure, and a skin graft using the foreskin may be required. For this reason it is important not to have the baby circumcised before hypospadias surgery, in case the foreskin is needed.

In mild cases, the foreskin can either be reconstructed or the result can be that of a circumcised penis, according to the parents’ preference. Support to help families understand and normalise genital variations can be helpful.

Obstruction of the renal pelvis#

An obstruction of the renal pelvis means urine cannot drain properly from the kidney into the bladder. One or both ureters may be affected. This condition occurs in around one in 350 babies. Symptoms can include recurrent urinary tract infections and, sometimes, impaired growth.

This condition is also known as ureteropelvic junction obstruction or pelvi-ureteric junction obstruction. The exact cause is unknown, but genetic factors are thought to contribute. Structures that can block the flow of urine include muscle differences in the wall of the ureter, unusual twists or bends in the ureter, or a blood vessel pressing on it.

Widening (dilatation) of the kidney is often detected during pregnancy ultrasounds, and a follow-up ultrasound is usually arranged.

Renal agenesis#

Renal agenesis means a kidney has not formed. If both kidneys are missing, the baby will not survive. A baby can manage with one functioning kidney, because the organ enlarges to cope with the extra workload.

Key points#

• Hypospadias is one of the more common genital variations, occurring in around one in 150 births
• The causes of hypospadias are unknown
• Hypospadias surgery is most commonly performed between 6 and 18 months of age
• It is important not to have your son circumcised before hypospadias surgery, in case the foreskin is needed
• Symptoms of renal pelvis obstruction can include recurrent urinary tract infections and impaired growth

Where to get help#