Normal uptake with prompt washout. Rapid rise in curve, peaks at 2-5 minutes, with a normal rapid washout (curve falls quickly).
Type 2 ‘ Obstructed
Rising uptake curve, no response to diuretic ie curve continues to rise (obstruction). Anything but an exponentially falling curve could be considered evidence of obstruction. Beware false positive ‘ dehydration, poor renal function, massive dilatation, bladder effect.
Type 3a ‘ Hypotonic
An initially rising curve which falls rapidly in response to diuretic (non-obstructive dilatation) Dilatation result of stasis rather than obstruction.
Type 3b ‘ Equivocal
An initially rising curve which neither falls promptly following injection of diuretic nor continues to rise.
Type 4 ‘ Delayed compensation (Homsy)
Delayed double peak. The initial washout due to the diuretic is good but the curve flattens or even rises. Flow rate too high for system and obstructs. (Intermittent obstruction)
In equivocal cases, antegrade pyelography allows examination of the flow of contrast through the PUJ after puncture of the collecting system. This allows the performance of antegrade studies that will help define the nature and exact anatomic site of obstruction. It also allows decompression of the system in patients with associated infection or compromised renal function and allows assessment of recoverability of renal function after decompression. When there remains some doubt as to the clinical significance of a dilated collecting system, placement of a percutaneous nephrostomy tube allows access for dynamic pressure perfusion studies. First described by Whitaker in 1973, the renal pelvis is continuously perfused at 10 mL/ min with normal saline solution or dilute radiographic contrast solution under fluoroscopic control. Renal pelvic pressure is monitored during the infusion, and the pressure gradient across the UPJ is determined. During the infusion, the bladder is continuously drained with an indwelling catheter to prevent transmission of intravesical pressures. Renal pelvic pressure ranging up to 12 to 15 cm H2O during this infusion suggests a nonobstructed system. In contrast, pressures in excess of 15 to 22 cm H2O are highly suggestive of a functional obstruction.28
Is occasionally used to elucidate uterine anatomy. It may differentiate between PUJ and VUJ anomalies if this was equivocal on pre-operative imaging studies. In most cases, this study is performed at the time of the planned operative intervention to avoid the risk of introducing infection in the face of obstruction.
Indication for treatment
Indications for intervention for congenital UPJO include presence of symptoms associated with obstruction, impairment of overall renal function or progressive impairment of ipsilateral function, development of complication in the form of infection, stones or rarely development of hypertension.29 Primary goal of intervention is relief of symptoms along with preservation or improvement of renal function. Traditionally, such intervention should be a reconstructive procedure aimed at restoring non-obstructed urinary flow.
Active urinary tract infection should be excluded before surgery. Appropriate antibiotics should be started, and a negative culture should be obtained preoperatively.
Open pyeloplasty in literature has been described with a number of incisions and approaches but the most popular anatomic approach to the ureteropelvic junction has been extraperitoneal flank approach. Excellent exposure of ureteropelvic junction is obtained when this incision is utilized through the bed of the twelfth rib. An anterior extraperitoneal approach is chosen by some because it allows surgical repair with minimal mobilization of the pelvis and proximal ureter. Cases of ureteropelvic junction obstruction with associated horseshoe kidneys, or when there is anterior malrotation of the kidney an anterior extraperitoneal approach is more useful. This approach can also sometimes be utilised for those who have had prior flank operations. The posterior lumbotomy approach can be considered in cases with a significant extraperitoneal component of the uretropelvic junction obstruction. Posterior lumbotomy provides direct exposure to the UPJ and again allows repair with minimal mobilization of the surrounding structures. Like the anterior extraperitoneal approach, posterior lumbotomy is best suited FOR relatively thin patients without previous ipsilateral surgery.
This procedure was popularized and modified by Anderson & Hynes30, and can be easily applied or modified to reconstruct vast majority of ureteropelvic junction obstructions. It is the most popular of all procedures because of its versatility. Advantages of dismembered pyeloplasty is that it allows the complete excision of the anatomically strictured area when compared to flap procedures, also its utilization is not dependent on whether the ureteral insertion is high or normal. Few rare scenarios where the dismembered pyeloplasty is not useful is when there is a lengthy proximal ureteral stricture associated with a poorly accessible intrarenal pelvis.
After entering the retroperitoneum and ureter, ureteropelvic junction and pelvis are identified. Ureter along with periureteral tissue is dissected upto pelvis to preserve delicate ureteral vasculature. Fine marking sutures should be placed on the medial and lateral aspects of the renal pelvis, just superior to the ureteropelvic junction obstruction, and on the lateral aspect of the ureter, inferior to the area that is to be transected in order to maintain the proper orientation of ureter. The strictured ureteropelvic junction is the excised and ureter is spatulated over the lateral aspect. The superior aspect of the renal pelvis is closed to its most dependent aspect where the ureteral anastomosis is performed. The apex of the spatulated ureter is then anastomosed to the most inferior aspect of the renal pelvis, while the medial portion of the ureter is sutured to the superior aspect of the newly constructed ureteropelvic junction. The anastomosis should be performed with absorbable sutures placed full thickness through the ureteral wall and renal pelvis, in an interrupted or running fashion in a water tight manner over double J stent.