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
• Wilm's 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 (i.e., anorectal malformations, malrotated bowel), or skeletal problems (i.e., cleft lip/palate, clubfoot, polydactyly)

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

Symptoms

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. Symptoms will vary depending upon which body system is involved. The symptoms of horseshoe kidney may resemble other conditions or medical problems. Always consult your child's physician for a diagnosis.

Diagnosis

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 physician 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.
• Blood tests (to determine how well the kidneys may be functioning)
• Urine tests (including a culture)

Treatment

In a child without symptoms, treatment may not be necessary. If your child has complications, he/she may require supportive treatment, which means his/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 physician 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 physician who specializes in disorders and care of the urinary tract and the male genital tract) and/or a nephrologist (a physician who specializes in disorders or diseases of the kidney) for evaluation.