Horseshoe Kidney
Horseshoe kidney is a congenital condition in which the two kidneys are fused together at their lower poles, forming a U-shaped structure. Although many people with a horseshoe kidney have no symptoms and discover it incidentally on imaging, the abnormal position and shape can increase the risk of kidney stones, urinary tract infections, and blockage of urine flow. Kidney function is usually normal, but some individuals may experience complications.
What is it?
Horseshoe kidney occurs when the kidneys fuse during fetal development, typically at the lower poles, creating a single connected unit that sits lower in the abdomen than usual. Because the fused kidneys cannot rotate or ascend normally, the ureters may insert at higher angles, which can affect urine drainage. Despite the abnormal anatomy, most people maintain normal kidney function.
Imaging—especially CT or MRI—clearly shows the fusion bridge (called the isthmus) connecting the two kidneys. Ultrasound may detect the condition but may not show all details. Imaging also helps identify complications such as hydronephrosis, stones, or associated anatomical variations.
Important to Know
Many individuals with horseshoe kidney remain asymptomatic throughout life. When symptoms occur, they are usually related to obstruction, stones, or infections. People with horseshoe kidneys may also have an increased risk of certain congenital conditions or vascular variations, which may be relevant during surgery or other procedures.
Red flag symptoms include severe flank pain, fever, persistent urinary infections, blood in the urine, or difficulty urinating—these may indicate obstruction or stones. Regular monitoring may be recommended if the kidney drainage pattern is abnormal or if recurrent issues develop.