Horseshoe kidney is the most common type of kidney fusion, a congenital disorder that occurs during fetal development. In infants born with a horseshoe kidney, the kidneys are fused, forming a U-shaped organ similar in shape to a horseshoe. Another, much less common, variety of kidney fusion is ectopic kidney.
Causes of Horseshoe Kidney
Most people have two kidneys, one on each side of the back of the abdominal cavity. In patients born with horseshoe kidney, however, the kidneys fuse as they rise from the pelvic region during fetal development. This abnormality occurs in 1 out of 400 to 500 newborns and appears to be more frequently found in male offspring. A genetic disorder, horseshoe kidney may occur as part of another congenital condition, such as Turner syndrome, or may appear as an independent congenital defect.
Symptoms of Horseshoe Kidney
While some types of renal fusion rarely cause symptoms, horseshoe kidney results in symptoms in as many as 70 percent of patients who are likely to experience one or more of the following:
- Abdominal pain
- Kidney stones
- Urinary tract infections
- Blood in the urine
People with renal fusion have an increased, although still low, risk of developing malignant kidney tumors.
Diagnosis of Horseshoe Kidney
Renal fusion is usually diagnosed by performing a series of tests on those patients experiencing symptoms or complications associated with this condition. These tests may include:
- Renal ultrasound
- Voiding cystourethrogram (VCUG)
- Intravenous pyelogram (IVP)
- Blood tests
- Urine tests
The VCUG is used to examine the child's urinary tract as the bladder is filled with fluid colored with a contrast dye. X-rays are taken during the filling and emptying of the bladder to determine whether there is any abnormal reflux of urine back into the ureters or kidney. The IVP uses intravenous contrast dye to make small structures of the urinary tract more visible to the urologist. Blood and urine tests are administered to check kidney function.
Treatment of Horseshoe Kidney
When patients with horseshoe kidney are asymptomatic, no treatment is necessary. When there are complications, supportive treatment is required, though the disorder cannot be cured. Treatment steps that may be taken include administration of antibiotics to treat infections of the urinary tract and surgery to remove obstructions, like kidney stones, in order to improve urine flow.
Unfortunately, surgery does not relieve the kidney pain sometimes associated with this congenital problem. It is important that patients with horseshoe kidney make any new doctors aware of their condition, particularly if they are preparing to have abdominal surgery.