Duplex Kidney

Overview

What is a duplex kidney (duplicated ureters)?

Duplex kidney, also known as duplicated ureters or duplicated collecting system, is the most common birth defect related to the urinary tract. This occurs due to an incomplete fusion of the upper and lower pole of the kidney which creates two separate drainage systems from the kidney.

Most people do not need treatment.

What are the ureters?

Ureters are long, narrow tubes that drain urine from your kidneys to your bladder. Normally one ureter leads from each kidney to your bladder. In the case of duplicated systems, two ureters drain a single kidney. One ureter drains the upper pole of your kidney and the other drains the lower pole. This condition may affect one or both kidneys.

What are the types of duplex kidney?

Duplex kidney can take on one of two forms:

  • Incomplete: Two separate ureters are attached to the same kidney but join together at some distance away from the kidney to form a single ureter that enters the bladder.
  • Complete: Two separate ureters lead away from the same kidney and enter the bladder separately.

How common is duplex kidney (duplicated ureters)?

About 0.7% of the healthy adult population and 2% to 4% of patients with urinary tract issues have duplicated ureters. Incomplete duplication is three times more common than complete duplication, which is estimated to appear in about one in every 500 people.

Who is more likely to have duplex kidney?

Both boys and girls are affected, but the condition is more common in females.

Does duplex kidney cause pain?

No.

Symptoms and Causes

What causes duplex kidney?

Duplex kidney is a result of errors in cell division that occur during the development of the fetus inside the mother’s womb. There is no evidence that suggests anything during pregnancy causes the defect. However, there is evidence to show that the condition can be passed from parent to child. If one parent has a duplex kidney, the child has a 50-50 chance of also being born with this condition.

What are symptoms and complications of duplex kidney (duplicated ureters)?

As long as your duplicated ureters drain normally into your bladder they should not cause any symptoms. If symptoms do occur, it is usually in the case of complete duplicated ureters.

A duplex kidney can occur with other abnormalities of your urinary system. One common abnormality is an ureterocele, which occurs when the end of the ureter does not develop properly, and urine flow is obstructed. This results in a balloon-like swelling as urine builds up at the point where the ureter and bladder connect. In addition, urine can reflux back toward the kidney through the second ureter, which often has a weak valve because it joins the bladder in an abnormal location.

A number of symptoms can occur when one of the ureters is ectopic, which means it drains to somewhere other than the bladder. Symptoms of an ectopic ureter include:

  • Hydronephrosis: An ectopic ureter is usually narrower than it should be, leading to an obstruction in the flow of your urine. Your urine gets backed up and causes the kidney and ureter to swell.
  • Urinary tract infection (UTI): Poor drainage makes it easier for bacteria to enter urine and travel to your bladder. UTIs result in painful urination.
  • Vesicoureteral reflux: Urine backs up and flows in the wrong direction (up toward the kidney instead of down toward the bladder). It is important for a provider to grade the reflux, as a child may be able to outgrow a lower grade of reflux but may need more extensive treatment if the reflux is a higher grade. Kidney infections or renal scarring can result from reflux.
  • Incontinence (inability to control urination): In boys, this symptom may not be present, however, you may see scrotal swelling or UTIs (Urinary Tract Infections) may occur. In girls, rather than completely losing bladder control, there is a dampness due to a steady leakage.

How do you get duplex kidney (duplicated ureters)?

The duplication occurs during embryological development and is present at birth.

Diagnosis and Tests

How is duplex kidney diagnosed?

Duplicated ureters are usually found during childhood, due to the presentation of UTIs or incontinence. Sometimes they are not discovered until adulthood as symptoms may resemble other health problems, making it difficult to arrive quickly at a correct diagnosis.

What tests are performed?

A number of tests can help find duplicated ureters:

  • Ultrasound of your kidneys and bladder can show if there is a duplicate system.
  • Computed tomography (CT): Multiple scans are assembled into a three-dimensional image of a body structure.
  • Magnetic resonance imaging (MRI): An injected liquid dye is traced to show how your kidneys and urinary system function.
  • Are you incontinent?
  • Do you have any stinging or pain when you urinate?
  • Have you had an ultrasound of your kidneys and bladder?
  • Were your parents or other family members born with duplicated ureters?

Management and Treatment

How is duplex kidney treated? What procedures are performed?

Most people do not need treatment.

If needed, treatments include:

  • Ureteroureterostomy: The ectopic ureter is split near your bladder, then sewn into the normal ureter of the lower part of your kidney. This allows urine from the upper part of the kidney to drain normally.
  • Ureteral reimplantation: The ectopic ureter is split near the bottom and sewn into your bladder. This allows urine to drain correctly and not flow backwards.
  • Nephrectomy: This treatment is rarely used – it’s a last resort. In it, some or all of your kidney that is not working correctly is surgically removed. This eliminates incontinence and decreases the chance of infection. This surgery should be used only when kidney function is poor and the other kidney is operating normally.

Prevention

What can be done to prevent duplex kidney?

There is no known way to prevent a duplex kidney, as it results from a birth defect. However, the previously discussed surgeries can be performed to relieve symptoms and protect the kidneys from damage.

Outlook / Prognosis

What’s expected after duplex kidney (duplicated ureters) is treated?

The amount of recovery time needed after surgery depends on the procedure performed and the age of the patient. Children usually need one to two days in the hospital for recovery, then continued rest at home for one to two weeks.

An ultrasound of your kidney is usually done four to six weeks after surgery.

No long-term problems with kidney function or sexual function will result from treatment.

Living With

Can I live a normal life with duplex kidney (duplicated ureters)?

Typically there are no symptoms of duplex kidney. However, if you have another condition related to the urinary tract, or if a ureter is ectopic, then your quality of life might be effected. You may need to have tests done and procedures performed. Fortunately, these conditions aren’t life-threatening and the treatments are effective.

How do I take care of myself?

There are no at-home treatments for duplex kidney. However, if you or your child have surgery, be sure to follow all of your healthcare providers’ instructions exactly.

What questions should I ask my healthcare provider about duplex kidney?

  • Are there any medications I should take?
  • Which of the two types of duplex kidney do I have?
  • Do I need surgery? What kind?
  • Do I need to see a specialist?
  • Do I need a referral to see a specialist?
  • Do you think my symptoms will go away on their own?
  • If I have duplex kidney, should I have my child tested?

A note from Cleveland Clinic

Although duplex kidney (duplicated ureters) isn’t a life-threatening condition, or one that typically causes symptoms, it may require treatment. Duplex kidney can happen alongside a number of other conditions related to the urinary tract. Make sure you take those conditions, like incontinence and urinary tract infections, seriously – get them treated right away. You may not even know you have duplex kidney until you have a different condition. Be sure to connect with your healthcare providers and follow their instructions.

Last reviewed by a Cleveland Clinic medical professional on 12/04/2020.

References

  • Fernbach SK, Feinstein KA, Spencer K and Lindstrom CA. Ureteral duplication and its complications. Radiographics 1997; 17: 109-127. Accessed 12/4/2020.
  • Radiopaedia.org. Duplex collecting system. (http://radiopaedia.org/articles/duplex-collecting-system) Accessed 12/4/2020.
  • Urology Care Foundation. What is ectopic ureter? (http://www.urologyhealth.org/urologic-conditions/ectopic-ureter) Accessed 12/4/2020.
  • Urology Care Foundation. What is an ureterocele? (http://www.urologyhealth.org/urologic-conditions/ureterocele) Accessed 12/4/2020.

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