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Pelvi-Ureteric Jucnction Obstruction

  1. PUJ obstruction is the most common cause of antenatal and neonatal hydronephrosis. PUJ   obstruction presents with pain, hematuria, urosepsis, failure to thrive, or a palpable mass.
  2. Fifty percent of patients diagnosed with antenatal hydronephrosis will be found to have a PUJ obstruction on further work-up.
  3. Frequency:
    1. PUJ obstruction is seen in 50% of patients diagnosed with antenatal hydronephrosis.
    2. There is a male to female ratio of 2-3:1. *
    3. In general, the left kidney is more commonly affected. Q
  4. Etiology:
    1. Idiopathic
    2. Intrinsic obstruction occur secondary to stenosis from scarring.
    3. Ureteral hypoplasia may result in abnormal peristalsis through the PUJ.
    4. Abnormal or a high insertion of the ureter into the renal pelvis.
    5. Crossing lower pole renal vessel(s) or entrapment of the ureter by a vessel (rare cause).
    6. Rotation of the kidney, such as renal ectopy, and renal hyper-mobility.
    7. There is impaired drainage of urine from the kidney into the ureter, resulting in elevated intrarena backpressure, dilation of the collecting system, and hydronephrosis.
  5. Clinical:
    1. Neonates presenting with hydronephrosis should be placed on prophylactic antibiotics (amoxicillin 15 mg/kg) to prevent urinary tract infections.
    2. If renal sonography demonstrates hydronephrosis without reflux on VCUG, then a diuretic renal scan (MAG-3, DTPA, or DMSA) should be performed to quantify relative renal function and to define the extent of obstruction.
    3. Older children may present with urinary tract infections (UTI), a flank mass or intermittent flank pain secondary to a primary PUJ obstruction. Hematuria may also be a presenting sign if associated with infection.
    4. Adults can present with a variety of symptoms, including back and flank pain (Most common presentation), UTI, and/or pyelonephritis. Through detailed history, the pain may be correlated with periods of increased fluid intake or ingestion of a food with diuretic properties (Dietl's crisis- pain is relieved and the swelling disappears when a large volume of urine is passed.).
  6. Indications of Dilation / Surgical repair:-
    1. Dilation of the intrarenal collecting system or hydronephrosis does not necessarily imply obstruction.
    2. Renal pelvic dilation should be followed with serial imaging for changes in dilation, renal parenchymal thickness and/or the presence of scarring, and function.
    3. Surgical repair is indicated if there is a significant differential in serial imaging or if progressive deterioration of renal function occurs. Q
    4. Similarly, in adults, repair is recommended if ureteral obstruction is demonstrated either on nuclear medicine renal scan or IVP.
  7. Lab Studies:
    1. All patients should be evaluated with a CBC, coagulation profile, electrolytes, and assessment of overall renal function with BUN and creatinine and urine culture.
    2. Increased concentration of B2M (Beta 2 microglobulin) is a marker of significant obstruction.
  8. Imaging Studies:
    1. In children, a renal ultrasound and voiding cysto-urethrogram are performed.
    2. IVP is used to evaluate patients with possible PUJ obstruction, however, diuretic renograms is useful in advanced cases of obstruction with poor renal function.
    3. In children, a retrograde ureteropyelogram to define the entire ureter is sometimes performed just prior to surgical repair
    4. It is one of the first tools that have been used to assess upper ureter & renal pelvis.
  9. Diagnostic Procedures:
    1. In those patients where the diagnosis of obstruction is equivocal, a Whitaker antegrade pressure-flow study may be performed.
    2. This test begins with the placement of a small diameter nephrostomy.
    3. Dilute contrast medium is instilled and intrarenal collecting system pressure monitored.
    4. Perfusion is started at the rate of 10 ml / min. until steady state equilibrium of pressure is reached. Bladder is continuously drained with a catheter.
    5. At a flow rate of 10 ml/min, differential pressure (pelvic pressure – vesical pressure) below 13 cm of water is normal; 14-22 suggests mild obstruction,  > 22 suggest moderate to severe obstruction. Q
    6. While function cannot be assessed, relative resistance and pressure within the renal pelvis can be determined.
  10. Treatment
    1. Medical therapy:
      1. In children, medical therapy is focused on maintaining sterile urine and assessment of renal function and the degree of hydronephrosis.
      2. Patients are typically followed with routine renal ultrasounds and nuclear medicine renograms if an incomplete obstruction is defined on imaging.
    2. Surgical therapy:
      1. Anderson – Hynes pyeloplasty (dismembered pyeloplasty) is the surgical option of choice.
      2. Surgical intervention to treat an obstructed ureteropelvic junction is warranted, especially with deterioration of renal function.
      3. The principles of surgical repair as initially described by Foley include the following:
        • Formation of a funnel
        • Dependent drainage
        • Water-tight anastomosis
        • Tension-free anastomosis
        • In children, the procedure of choice is an Anderson-Hynes dismembered pyeloplasty.
        • The success of dismembered pyeloplasty is greater than 95%.
        • Treatment alternatives include an antegrade or retrograde endopyelotomy, which is an endoscopic incision performed through the obstructing segment (Chances of recurrence is more).
        • Success rates with the percutaneous and ureteroscopic endopyelotomy range from 80-90%.
        • Traditional open or laparoscopic pyeloplasty is also indicated after failed endopyelotomy.
        • The Foley Y-V plasty is useful for the high insertion variant.
        • Spiral and vertical flaps, such as Culp and DeWeerd and Scardino and Prince, are useful when a long-strictured segment of diseased ureter is encountered.
        • Ureterocalicostomy, anastomosis of the ureter to a lower pole renal calyx, is most often reserved for failed open pyeloplasty where there is no extrarenal pelvis.
  11. Complications
    1. Urinary tract infection and pyelonephritis,
    2. Urinary extravasation and leakage,
    3. Recurrent PUJ obstruction or stricture formation.
    4. Specific complications from endopyelotomy include: Significant intra-operative bleeding if the endoscopic incision is made inadvertently into a major polar vessel, postoperative infection, and recurrence of obstruction. 

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