Laparoscopic Pyeloplasty in a Solitary Kidney

Nauman Zafar; John Leyland; Nimish C Shah*


Nat Clin Pract Urol. 2007;4(11):625-629. 

In This Article

Discussion of Diagnosis

A UPJ obstruction can be defined as a restriction to the flow of urine from the renal pelvis to the ureter that, if left uncorrected, will lead to progressive renal deterioration.[1]

UPJ obstruction is the most common congenital abnormality of the ureter. Congenital causes of UPJ obstruction include a non-peristaltic segment of ureter or a true congenital stricture. Intrinsic obstruction may also occur due to valves or kinks produced by infoldings of the ureteral mucosa and musculature.

Aberrant or accessory lower pole vessels can cause extrinsic obstruction at the UPJ. Controversy persists regarding the potential role of aberrant vessels in the functional obstruction of UPJ. In many cases there can be an associated intrinsic lesion at the UPJ that causes dilatation and apparent ballooning of the renal pelvis over the polar vessel.[1] The incidence of crossing vessels as detected by Doppler ultrasound in kidneys with and without UPJ obstruction has been reported as 79% versus 39%, respectively.[2]

UPJ obstruction can also be caused by acquired lesions. These include benign tumors such as fibroepithelial polyps, urothelial malignancy, urolithiasis, and scarring or ischemia, which may result after inflammation or surgical intervention. In children, severe vesicoureteric reflux can result in secondary UPJ obstruction due to subsequent elongation and tortuosity of the ureter, which can cause kinking of the UPJ.[1]

UPJ obstruction is often associated with other renal abnormalities such as contralateral renal agenesis as in the case described above. Other associations include duplication of the collecting system, renal ectopia, multicystic dysplastic kidney and horseshoe kidney. Bilateral UPJ obstruction occurs in 10–15% of cases.[3]

The widespread use of antenatal ultrasound has dramatically increased the detection rate of asymptomatic newborns with UPJ obstruction. UPJ obstruction can present clinically at any time up to adulthood even though it is generally a congenital problem. A frequent presentation in older children or adults is intermittent abdominal or flank pain, often associated with nausea and/or vomiting. The pain might become apparent during times of maximum diuresis such as after consumption of large volumes of fluid, especially alcohol.

Less common presentations include urinary tract infection (UTI), renal calculi or hematuria, which may occur after minor trauma. Azotemia may be the primary presentation in a small number of patients with bilateral obstruction or a single functioning kidney. In the case described above, renal function was normal despite the single kidney. Normal function might be explained by the intermittent and possibly partial nature of the obstruction.

UPJ obstruction is also increasingly an incidental finding in asymptomatic children or adults who undergo abdominal imaging for an unrelated reason.


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