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July 1996, Volume 46, Issue 7

Original Article

Evaluation of Uret.eropelvic Junction Obstruction (UPJO) by Diuretic Renography

S. Sultan  ( Sindh Institute of Urology and Transplantation, Dow Medical College, Karachi. )
M. Zaman  ( Civil Hospital and Atomic Energy Medical Centre, Jinnah Postgraduate Medical Centre, Karachi. )
S. Kamal  ( Civil Hospital and Atomic Energy Medical Centre, Jinnah Postgraduate Medical Centre, Karachi. )
N Zafar  ( Sindh Institute of Urology and Transplantation, Dow Medical College, Karachi. )
A. Rizvi  ( Sindh Institute of Urology and Transplantation, Dow Medical College, Karachi. )

Abstract

Of 52 cases with 56 affected renal units having symptoms and signs suggestive of Ureteropelvic Junction Obstruction (UPJO) evaluated by conventional (F-i-IS) diuretic renography where frusemide is given 15 minutes post-injection of radiopharmaceutical m 99 TC.DTPA. F+15, twelve (21%) showed a good clearance (group A), 16 (28%) showed partial (group B) and 28 (50%) a poor clearance pattern (group C) indicating a definite obstruction. A high flow (F-15) diuretic renography where frusemide is given 15 minutes prior to the radiopharmaceutical m99  TC.DTPA, was done in 23 cases with 27 affected renal units. Eleven renal units showed a good clearance (group A). Of these, 7 (64%) showed a persistent good clearance, 3 (27%) converted to poor clearance and 1 (9%) to partial clearance pattern. Of 8 renal units in group B, 5 (63%) converted to poor clearance and two (25%) to good clearance on F-IS and one remained unchanged. All renal units which presented as poor clearance (group C) on conventional (F+15) diuretic renography remained unchanged on high flow (F-15) diuretic renography. In majority of cases conventional (F÷15) renography gave a reliable assessment of the upper tract drainage, however, since equivocal group was resolved by the F-15 and the intermittent obstruction group was definitely diagnosed, highflow (F-IS) diuretic renography was more conclusive in assessment as compared to F+15 (JPMA 46:143, 19%).

Introduction

Ureteropelvicjunction obstruction (UPJO) is a frequent congenital abnonnality of the urinary tract and a common cause of hydronephrosis1, which can present at any age2. It may be due to muscular deficiency in the terminal part of the renal pelvis or proximal urete3, leading to disorpnisation of propagation of waves of muscular contractions4.UPJO may occur because of crossing (aberrant) vessels or high insertion of ureteropelvic junction (UPJ) 5.
Not all dilated pelvicalyceal systems are obstructed6, intermittent obstructions may not always be easily apparent and there may not be any significant abnormality on ultra­sonography (US) or intravenous urography (IVU) 7  . Nonethe­less, UPJO may cause significant symptoms or deterioration of renal function Diuretic renography8,9  is frequently used for evaluation of UPJO, being a non-invasive technique as compared to pressure studies10, It gives, more information on function and emptying rates in individual kidneys than US and IVU. Views differ as to ts true diagnostic value7. To improve the accuracy of diuresis renogram in idiopathic hydroneph­rosis, various modifications of technique and analysis have been introduced8,18. This study was undertaken to determine the role of (conventional) F+15 diuretic renography where diuretic given 15-20 minutes after the injection of radiophar­maceutical m99.  Technetium diethylenetriaminepetaacetic acid (m99  TC. DTPA) and F-15 (highflow) diuretic renogra­phy where diuretic is given 15 minutes prior to the injection of radiopharmaceutical (m99  TC. DTPA) in evaluation of UPJO18.

Patients and Methods

Fifty-two cases with symptoms and signs suggestive of ureteropelvic junction obstruction (UPJO) were included in this study. A dilated pelvicalyceal system without ureteric dilatation on ultrasound and intravenous urography (IVU), were the main inclusion criteria.
History was taken and general and physical examination carried out, especially on findings related to UPJO. Specific exclusion criteria were dilated ureters on IVU or sonography, vesicoureteric reflux (VUR), neurogenic urinaiy bladder and lower urinary tract obstruction, history of surgery on the affected side (iaterogenic UPJO) and poor relative renal function (R.F) of the affected renal unit. Radiological examina­tion included IVU, s6nography of the kidneys and m99. Technetium diethylenetriarninepetaacetic acid (m99  TC. DTPA) diuretic renography for further assessment of renal function and the severity of obstruction at UPJ. Initial scans were taken to observe clearance patterns with frusemide given 15-20 minutes post-injection (PI) of radiopharmaceutical DTPA (F+15), following the protocol of O’Reilly 199218. After the initial scans, a second modality was tested, where fnisemide was given 15 minutes prior(F-l5)to the radiophar­ maceutical DTPA18. F-iS scans were possible in23 cases with 27 affected renal units. A comparison of clearance pattern was done in these 27 renal units.

Results

Of 52 cases, 32 were males witha male to female ratio of 1.6 Majority of the patients were in age group 20-40yàrs. Clinical presentations showed flank pain to be commonest (92%) with an even distribution in right and left flank. Six had bilateral flank pain, of these only four bad bilaterally dilated pelvicalyceal system. Other features included generalised abdominal pain (4%). Intermittent renal mass was basically a presentation in children (15%) one infant presented with renal mass as a solitary complaint. Associated features were dysuria in 23% cases, followed by frank haematuria and fever. O*te case with bilateral dilated pelvicalyceal system presented as an incidentalfinding on sonography.
Ultrasound examination revealed a dilated pelvicaly­ceal system in all and hydronephrosis on IVU in 86% cases. Of the remaining 9%presented as non-functioning renal units on IVU and 5% as persistent nephrograms. Clearance pattern on m99  TC.DTPA diuretic renography of the 56 affected renal units showed a good clearance in 12 (2 1%) (group A) and partial clearance in 16 (28%).(group B). Twenty-eight (50%) (group C) showed a poor clearance pattern indicating a definite obstruction (Figure la, 2a, 3a).

Of 56 renal units, high flow (F-15) diuretic renography were possible in 23 caseswith 27 affected renal units. Eleven renal units showed good clearance (group A) on conventional diuretic renography and 7 (64%) showed a persistent good clearance pattern on high flow (F-iS) diuretic renography (Figure 2a, 2b). Three (27°to) converted to poor clearance (Figure Ia, ib), while 1 (9%) converted to partial clearance pattern (Figure 2a, 2b).


Of 8 renal units which showed partial clearance (group B) on conventional diuretic renography, 5 (t53°/o) converted to poor clearance (Figure 4a, 4b)

and 2 (25%) converted to good clearance on high flow (F-IS) diuretic renography (Figure 2a, 2b). One remained unchanged as partial clearance. All 8 renal units which presented as poor clearance (group C) on conventional (F+15) diuretic renography remained un­changed on high flow (F-15) diuretic renography (Figure 3a, 3b).

A comparison of relative renal functions (RF) in the affected and unaffected renal units, assessed by the two methods of diuretic renography, showed no difference.

Discussion

The initial investigation for assessment of UPJO in this study was ultrasonography and a consistent finding was dilated pelvicalyceal System. While intravenous umgraphy showed hydronephrosis in majority of the patients, compared to US, IVU was able to give definite evidence pertaining to obstruction such as delayed excretion, non-visualised ureter, persistent nephrogram or non-functioning kidney. However, all these findings were static and inconclusive in pmviding evidence of dynamics or the functional state of the uretero­pelvic junction. In these situations the use of non-invasive isotope renography was found to be attractive as it could monitor individual renal function and emptying rates much more accurately. However, in certain cases it was unclear to make distinction between obstruction and atony. The conven­tional F+15 diuretic aenography had a considerable false negative rate for obstruction at UPJ in cases of intermittent UPJO11,19 This was also observed in our study where 56 affected renal units which were evaluated by F+15, only 28 (50%) could give definite obstructive pattern on renography. The remaining had either equivocal pattern (28%) or unob­structed pattern (21%).
Pressure flow studies show that a high urine flow rate is sometimes necessary for obstruction to be apparent20,21  but not all dilated systems are obstructed6. Therefore, modifica­tion (F- 15) of the diuresis renography19  which is designed to increase urine flow rates16,22 was undertaken, so that excre­tion could be assessed during maximum flow rates. We observed that patients who presented with typical symptoms of intermittent loin pain or intermittent renal mass, represented the group who obstruct only at high urine flow on F-15 and were not identified by F+15 diuretic renography (Figure 5a, 5b).

Those who presented with an equivocal pattern (partial clearance) on F+15 either showed obstructed or clearly unobstructed pattern on F-15 (Figures 2a, 2b, 4a,4b) thus reducing the number of equivocal results. The results of this study show that there was generally good agreement between the conventional F+15 and modified high flow F-15 diuretic renography, when the results of the conventional renogram were unequivocal, as all 8 cases with obstructed pattern (poor clearance) on F+l5 remained with obstructed pattern on F-15 (Figure 3a, 3b) as well. Similarly 7 (64%) of the 11 renal units which remained unobstructed showed a good clearance pattern (Figure Ia, Ib), reinforcing the concept that not all dilated systems are obstructed6. In conclusion although in majority of cases conventional F+15 diuretic renography gave a reliable assessment of the upper tract drainage, however, highflow F-iS diuretic renography was more conclusive, in assessment as compared to F+15, since the equivocal group was resolved by the F-15 and the intermittent obstruction group was definitely diagnosed. Thus, in situ­ations with limitation of facilities F-15 can be used as the first investigation. The argument in favour of F+15 in the context of perfusion and uptake pattern is only of academic interest19  since the purpose of investigation is primarily to diagnose obstruction via the clearance patterns. Thus it must be emphasised that the diagnostic value of diuretic renography depends on a clear understanding of pathophysiological mechanisms that come into play in urinary tract obstruction.

References

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