Patient Symptoms
- Increased renal pelvic pressure with vague back pain that often increases with intensity after an increase in fluid intake, nausea, vomiting, hematuria, urinary tract infection, pyuria, or hypertension
Diagnosis
- UPJ obstruction, although most often a congenital problem, can present clinically at any time of life.
- Historically, the most common presentation in neonates and infants was the finding of a palpable flank mass.
- The current widespread use of maternal, prenatal ultrasonography has led to a dramatic increase in the number of asymptomatic newborns being diagnosed with hydronephrosis, many of whom are subsequently found to have UPJ obstruction.
- In older children or adults, intermittent abdominal or flank pain, at times associated with nausea or vomiting, is a frequent presenting symptom.
- Hematuria, either spontaneous or associated with otherwise relatively minor trauma, may also be an initial symptom. Laboratory findings of microhematuria, pyuria, or frank urinary tract infection might also bring an otherwise asymptomatic patient to the urologist. Rarely, hypertension may be a presenting finding.
- Radiographic studies should be performed with a goal of determining both the anatomic site and the functional significance of an apparent obstruction.
- CT scan is frequently obtained for any patient presenting with acute flank pain.
- CT scans provide detailed anatomic and functional information to aid in diagnosis of UPJ obstruction.
- Both ultrasonography and CT scanning also have a role in differentiating acquired causes of obstruction such as radiolucent calculi or urothelial tumors.
- In neonates and infants, the diagnosis of UPJ obstruction has generally been suggested either by routine performance of maternal ultrasonography or by the finding of a flank mass.
- In either setting, renal ultrasonography is usually the first radiographic study performed.
- Ultrasonography should be able to visualize dilatation of the collecting system to help differentiate UPJ obstruction from multicystic kidney and determine the level of obstruction.
- UPJ obstruction and multicystic kidneys are distinguishable in the majority of cases by ultrasound alone.
- With UPJ obstruction, the pelvis is visualized as a large, medial sonolucent area surrounded by smaller, rounded sonolucent structures representing dilated calyces.
- At times, dilated calyces will be seen connecting to the pelvis via dilated infundibula.
- Diuretic renography is effective in predicting recoverability of function in cases in which intravenous urography has revealed nonvisualization. Diuretic renography allows quantification of the degree of obstruction and can help differentiate the level of obstruction.
- 99mTc-MAG3 is the preferred isotope because of favorable imaging and dosimetry considerations over 99mTc-DTPA or radioiodinated hippuran.
- Diuretic renography remains a commonly used study for diagnosing both UPJ and ureteral obstruction because it provides quantitative data regarding differential renal function and obstruction, even in hydronephrotic renal units.
- Diuretic renography is noninvasive and readily available in most medical centers.
- Diuretic renography can be used to follow patients for functional loss, most effectively when a standard protocol is used.
- The diuretic is given 20 minutes into the study to allow time for filling of the collecting system.
- There is evidence that the diuretic renography using MAG-3 is a most accurate study for patients with UPJ obstruction following therapeutic intervention.
Surgical Management
- Indications for intervention for UPJ obstruction include the presence of symptoms associated with the obstruction, impairment of overall renal function or progressive impairment of ipsilateral function, development of stones or infection, or, rarely, causal hypertension.
- The primary goal of intervention is relief of symptoms and preservation or improvement of renal function.
- Intervention should be a reconstructive procedure aimed at restoring nonobstructed urinary flow. This is especially true for neonates, infants, or children in whom early repair is desirable because these patients will have the best chance for improvement in renal function after relief of obstruction
- Timing of the repair in neonates remains controversial mostly because of difficulty in defining those kidneys truly at risk for functional obstruction.
- UPJ obstruction may not become apparent until middle age or later.
- If the patient is asymptomatic and the physiologic significance of the obstruction seems indeterminate, careful observation with serial follow-up studies may be appropriate, typically using diuretic renography.
- The majority of affected patients may ultimately benefit from reconstructive intervention.
- When intervention is indicated, the procedure of choice has historically been dismembered pyeloplasty.
- Less invasive endourologic approaches have a role as an alternative in many centers.
- Most recently, laparoscopic and robotic pyeloplasty has gained acceptance as primary therapy at centers with appropriate skills and technology.
- It is critical to discuss the risks and benefits of all available options with patients.
- Each patient should be advised individually on the basis of all the anatomic and functional information available preoperatively.
- Many patients will opt for a minimally invasive approach, even with the understanding that success rates may be lower, or secondary intervention may become necessary.
References
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