Renal duplication, also known as duplex kidney or duplicated collecting system, is a congenital condition where one or both kidneys have two ureters instead of one. This anatomical variation can involve partial or complete duplication of the ureter, the tube that drains urine from the kidney to the bladder. Renal duplication is often asymptomatic and discovered incidentally during imaging studies for other reasons. However, it can sometimes lead to complications such as urinary tract infections (UTIs) and obstruction.

The understanding of renal duplication dates back to the early study of human anatomy. Initially observed during dissections, the condition was primarily documented in the late 19th and early 20th centuries. Early studies and autopsies revealed the presence of this anomaly in a notable but relatively small percentage of the population. With the advent of modern imaging techniques, such as ultrasound, CT scans, and MRIs, the detection and diagnosis of renal duplication have become more precise. These technological advances have allowed for a deeper understanding of its implications and the development of more refined treatment protocols.


Renal duplication is a congenital condition that occurs during fetal development. The exact cause is not well understood, but it is believed to result from genetic and environmental factors that disrupt normal kidney development. The condition arises when the ureteric bud, an embryonic structure, splits abnormally, leading to the formation of two ureters from a single kidney.

Risk Factors

Several factors can increase the likelihood of renal duplication:

  • Family History: A family history of renal anomalies or other congenital abnormalities.
  • Genetic Syndromes: Certain genetic conditions may be associated with an increased risk of renal duplication.
  • Environmental Factors: Factors affecting fetal development during pregnancy, although specific influences are not well defined.


While many individuals with renal duplication are asymptomatic, potential complications include:

Urinary Tract Infections (UTIs): Increased risk of infections due to abnormal urine flow or incomplete bladder emptying.

Vesicoureteral Reflux (VUR): Backflow of urine from the bladder into the ureters and kidneys, leading to kidney damage.

Obstruction: Blockage in the urinary tract, causing hydronephrosis and potential kidney damage.

Ureterocele: A cystic dilation of the duplicated ureter where it enters the bladder, which can obstruct urine flow.


There is no known way to prevent renal duplication as it is a congenital condition. However, early detection and management can help prevent complications and preserve kidney function. Regular follow-up with a healthcare provider is essential for individuals diagnosed with renal duplication, particularly if they experience recurrent UTIs or other related symptoms.


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