Horseshoe Kidney

What is a horseshoe kidney?

Horseshoe kidney occurs in about one in 500 children. It occurs during fetal development as the kidneys move into their normal position in the flank area (area around the side, just above the waist). With horseshoe kidney, however, as the kidneys of the fetus rise from the pelvic area, they fuse together at the lower end or base. By fusing, they form a "U" shape, which gives it the name "horseshoe."

One-third of individuals with horseshoe kidney will have at least one other anomaly or complication involving the cardiovascular system, the central nervous system, or the genitourinary system, such as the following:

• Kidney stones. Crystals and proteins that form stones in the kidney that may lead to a urinary tract obstruction.

• Hydronephrosis. Enlargement of the kidneys that usually results from a urinary tract obstruction.

• Wilms tumor. An embryonic tumor of the kidneys that usually occurs during early childhood.

• Renal cancer, or polycystic kidney disease

• Hydrocephaly and/or spina bifida

• Various cardiovascular, gastrointestinal findings (e.g., anorectal malformations, malrotated bowel), or skeletal problems (e.g., cleft lip/palate, clubfoot, polydactyly)

Horseshoe kidney can occur alone or in combination with other disorders.

What are the symptoms of horseshoe kidney?

About one-third of children will have no symptoms. One-third of individuals with horseshoe kidney will have another anomaly or other complication involving the cardiovascular, nervous, or genitourinary system. The symptoms of horseshoe kidney may resemble other conditions or medical problems. Always consult your child's doctor for a diagnosis.

How is horseshoe kidney diagnosed?

In a child without symptoms, diagnosis or treatment may not be necessary. If your child is having any of the mentioned complications, your child's doctor may order one or more of the following diagnostic tests:

• Renal ultrasound. A diagnostic imaging technique that uses high-frequency sound waves and a computer to create images of blood vessels, tissues, and organs. Ultrasounds are used to view internal organs as they function, and to assess blood flow through various vessels.

• Voiding cystourethrogram (VCUG). A specific X-ray that examines the urinary tract. A catheter (hollow tube) is placed in the urethra (tube that drains urine from the bladder to the outside of the body) and the bladder is filled with a liquid dye. X-ray images will be taken as the bladder fills and empties. The images will show if there is any reverse flow of urine into the ureters and kidneys.

• Intravenous pyelogram (IVP). A diagnostic imaging technique which uses an X-ray to view the structures of the urinary tract. An intravenous contrast of dye is given so that the structures can be seen on film. An IVP also reveals the rate and path of urine flow through the urinary tract.

• Blood tests. These determine how well the kidneys may be functioning.

• Urine tests. These tests include a culture.

What is the treatment for horseshoe kidney?

In a child without symptoms, treatment may not be necessary. If your child has complications, he or she may require supportive treatment, which means his or her symptoms will be treated, but there is no cure for the condition.

Specific treatment for horseshoe kidney will be determined by your child's doctor based on:

• Your child's age, overall health, and medical history

• The extent of the disorder

• Your child's tolerance for specific medications, procedures, or therapies

• Expectations for the course of the disorder

• Your opinion or preference

Your child may be referred to an urologist (a doctor who specializes in disorders and care of the urinary tract and the male genital tract) and/or a nephrologist (a doctor who specializes in disorders or diseases of the kidney) for evaluation.