Factors Accountable for Unabated Obstruction Following Pyeloplasty.

PURPOSE: Split renal function (SFR) and frusemide washout (FWO) are assessed by the DTPA renogram to measure the renal parenchymal functions as well as the evidence of obstruction, both for diagnosis and to treat the pelviureteric junction obstruction. In good number of renal units, both these parameters remain unaltered even after surgery and cause anguish to parents and referring physicians and are usually attributed toward "defective pyeloplasty." In this study, we have tried to single out the bona fide responsible factor for the bad outcome; either the nonreversible kidney or the restenosis of pyeloplasty. PATIENTS AND METHODS: We studied file of 69 patients in whom a double "J" (DJ) stent was left in situ for internal drainage for a duration of 8 weeks in the postoperative period. DTPA scans were performed preoperative, at 8 weeks with a stent in place, and at 12 and 24 months postremoval of the stent to assess renal function.
RESULTS: In our study, 45 patients (65.2%) showed improvement either in SRF or in FWO or in both after 8 weeks following pyeloplasty and 24 of 69 units (34.8%) did not show any change in renal function with DJ stent in place. Only in six units (8.7%), out of 69 units had deterioration of renal function after removal of DJ stent.
CONCLUSIONS: In our opinion, no improvement of renal function found in 24 units (34.8%) even with internal drainage with DJ indicates irreversible renal damage. In 45 units (65.2%), renal function reversed after pyeloplasty and DJ stent. However, after the removal of the DJ, functions deteriorated in six units (8.7%) due to restenosis following pyeloplasties. Copyright:

INTRODUCTION

In some renal units, split renal function (SRF) remains unchanged and frusemide washout (FWO) persists as obstructive curve even after pyeloplasty. As a consequence, parents and pediatricians become skeptical and annoyed mainly due to “unabated obstruction” as demonstrated in renal scan and blame it on the surgical procedure done. Conversely, the surgeons rely on the presence of preexisting irreversible renal disease for poor outcomes; for their defense. Our study is to fix the culpability either on the kidney or on pyeloplasty or on both.

Hydrotension in the renal pelvis is relieved following pyeloplasty and surgical reconstruction is kept in rest with the placement of a transanastomotic double “J” stent (DJ) for free drainage of urine for a period of 8 weeks. We know, in an obstructed kidney, function improves within 6–8 weeks following free drainage[1] provided renal parenchyma retains a potential of reversibility. Hence, we inferred; if diuretic renogram (DR) at 8th week did not show improvement in spite of free drainage with DJ following pyeloplasty, the renal parenchyma is likely to be irreversibly damaged. The parents and treating physicians can be informed at this point that kidney function may not improve in these patients. On the other hand, deteriorating renal function after removal of the DJ stent indicates an insufficient pyeloplasty.

PATIENTS AND METHODS

Since February 2003–January 2017, we studied files of 76 patients, age ranged from 7 months to 8 years (mean 23.2 months), and the institute ethical committee approved this study. All 76 renal units had obstructed FWO curve. Along with obstructed FWO, they had either (a) decreased SRF around 30% (b) increased anteroposterior diameter above 40 mm or (c) symptoms.

Six patients who had solitary renal unit, bilateral ureteropelvic junction (UPJ) obstruction, and calculus were excluded. We also excluded another four patients due to the inability to place a DJ stent during pyeloplasty.

We did pyeloplasty keeping DJ over reconstruction and continued prophylactic antibiotics for 8 weeks. Following 8 weeks, we did DR and ultrasonographic renometry (USG–R) for the assessment of functional and morphometric parameters of the kidney in the presence of continuous drainage with DJ. Morphometric parameters in USG–R at 8th week were regarded as baseline parameters for comparison with the next USG–R in the follow-up. We removed DJ at 8th week following DR and USG–R done.

We repeated USG–R at 6-month intervals; or earlier in symptomatic patients to watch changes in morphometric parameters. Accordingly, we advised DR if there was deterioration in morphometric parameters in USG–R. In uncomplicated cases, we performed DR at 12th and 24th months for the final assessment.

RESULTS

Sixty-nine out of 76 patients had the necessary investigations. Hence, we analyzed the outcome of 69 units. In the DR study, minimal improvement in FWO is considered if minimal recovery of 10% is detectable. Forty-seven units (68.2%) out of 69 did not show minimal improvement in FWO over a span of 24 months [Chart 1 and Table 1].

Chart 1

Outcome flowchart

Table 1

The outcome table

	In FWO	In SRF	Both in FWO and SRF	Either in FWO or in SRF
Outcome (n=69) in general
Improvement, n (%)	22 (31.9)	43 (62.3)	20 (28.9)	45 (65.2)
No improvement, n (%)	47 (68.2)	26 (37.7)	24 (34.8)
Outcome in units had more than 30% SRF before pyeloplasty (n=26)
Improvement, n (%)	17 (65.4)	23 (88.5)	15 (57.7)
No improvement, n (%)	9 (34.6)	3 (11.5)	11 (42.3)
Factors (kidney or pyeloplasty) responsible for ultimate outcome (n=69)
Bad kidney, n (%)	24 (34.8)
Good kidney, n (%)	45 (65.2)
Good pyeloplasty, n (%)	63 (91.3)
Bad pyeloplasty, n (%)	6 (8.7)
Failed pyeloplasty, n (%)	2 (2.9)

FWO: Frusemide washout, SRF: Split renal function

Five percent increase or decrease in SRF was labeled as improvement or deterioration, respectively. Accordingly, 26 units (37.7%) did not improve in SRF at 8th week following pyeloplasty with DJ. Twenty-five units out of 26 maintained the same status up to 2nd year. However, one asymptomatic patient out of those 26 units exhibited suspicion of obstruction in USG–R at 6th month and corroborated deterioration of >10% in SRF. That patient required revisional surgery.

On the better side, SRF of 43 units (62.3%) out of 69 found improved on DR at 8th week. Afterward, USG–R parameters in five units out of 45 good kidneys deteriorated at 6th month Chart 2. However, subsequent DR did not show deterioration in SRF in two units. The rest three units, those had around 10% improvement at 8th week showed deterioration, and two of those lost >5% from positive gain. Hence, they maintained on an around of preoperative level of SRF afterward. The rest one unit showed deterioration >10% and needed revisional ureterocalicostomy Chart 2.

Chart 2

Bad Pyeloplasties

Ultimately, 24 units (34.8%) improved neither in the FWO curve nor in SRF, and 45 units (65.2%) improved either in the FWO curve or in SRF. Only 20 units (29%) improved both in the FWO curve and in SRF [Charts 1,2 and Tables 1]. Unfortunately, six out of 69 patients (8.7%) had deterioration of parameters after the removal of the stent. They had no ureteric or ureterovesical junction obstruction. Five came from group of kidneys with good function and one from those with poor parenchyma Chart 2.

We have also analyzed the results in 26 patients who had 30% or more SRF on the affected side before surgery. It was interesting to observe that the percentage of improvement of renal function in this cohort was better. The SRF improved in 17 of 26 patients, whereas FWO improved in 23 units [Table 1]. This may signify that result of surgery in a better preserved parenchyma is likely to yield better results.

DISCUSSIONS

Some studies show functional improvement in SRF[2345] and some show improvement in FWO[678910] following pyeloplasty. On the other hand, some show persistent obstructive curve[101112] in FWO or minimal changes in SRF[1314] as outcome. However, none of those studies have singled out the factors, either 'renal factor', 'surgical factor' responsible for the bad outcome.

In our study, the DJ acted as an internal diversion on reconstruction for 8 weeks, giving rest to the reconstruction. Hence, renogram done at 8th week with DJ stent in place showed either improvement of renal function or status quo ante.

In 24 units (34.8%), either no improvement in FWO or minimal improvement in SRF (<5%) was found at 8th week. Hence, 24 units were singled out as 'bad kidneys' [Tables 1 and Chart 2].

On the improved part, 43 units out of 69 units (62.3%) had improvement in SRF with or without recovery in FWO. Another two units only improved in FWO. Hence, the parenchyma of 45 units, in aggregate, counted as improved in function. Thus, 45 units were singled out as 'good kidneys' [Tables 1]. Five units out of those 45 good units and one unit from those 24 bad units deteriorated after removal of DJ and denoted inadequacy in pyeloplasty. Thus, six units in aggregate had 'bad pyeloplasties'. Two units out of five units lost 5%–8% from their earlier gain of >10% of SRF and maintained on around the preoperative level of SRF afterward. Two units out of six needed revisional surgery. These two units were labeled as 'failed pyeloplasties' Chart 2.

Twenty-three units from “bad kidneys” and 40 units from “good kidneys,” making 63 units maintained their function without deterioration during follow-up of 2 years indicated 'good pyeloplasty' [Tables 1 and Chart 2].

In this study, we singled out the factor responsible for the final outcome with the help of DR, with and without DJ. Nevertheless, few ancillary queries evolved in this study.

We found obstructed FWO in 68.2% units in the presence of free drainage with DJ. Hence, the query arises: why the FWO showed obstruction in spite of free drainage with DJ? Was it due to ineffectual or absent peristaltic contraction of the renal pelvis? If so, why the pelvic contraction was ineffectual or absent?

We may explain pelvic contraction with the pacemaker system, i.e., interstitial cells of Cajal (ICC)[151617] of the renal pelvis. ICC acts on the smooth muscle of the pelvis for the peristalsis. Hence, the downregulation of ICC either due to damage from prolonged obstruction or absence of ICC may be responsible for inadequate contraction in the renal pelvis. Ultimately, inadequate or absent pelvic contraction is unable to propel urine with promptness toward the ureter[151617] and gets the blame of obstruction at the ureteropelvic junction.

ICC is necessary for the propelling of urine toward the ureter through open UPJ. This propelling force reflects in FWO, and this force is necessary for drainage of urine to relieve hydrotension, for the improvement of renal function. Forty-three units improved in SRF that means hydrotension got relieved in 43 units. That means, there also should be the improvement of FWO in 43 units. Nonetheless, only 20 units out of 43 units improved in FWO [Chart 1 and Table 1]. Hence, the query arises: how is the pyeloureteral drainage maintained in spite of obstruction in FWO? How is the pyeloureteral drainage possible other than the pacemaker system in the renal pelvis!

Abdominal pressure and the gravity maintain pyeloureteral drainage in slow pace, even in the presence of faulty pyeloureteral peristaltic machinery as the natural resistance at UPJ is removed by pyeloplasty. Gravity as well as erect posture facilitate propulsion of urine[1819] provided natural spasm/ obstruction at UPJ is removed by pyeloplasty. The same rationality demands pyeloplasty to be done at the most dependant part of the pelvis to get enhanced drainage. Similarly, George et al.[20] discourage bed rest as it is deleterious for the renal function in individuals with dilated upper urinary tracts.

Slow pyeloureteral drainage in ICC deprived pelvis is akin to slow gastric drainage in a vagotomized, hypocontractile stomach. In that situation, the stomach needs the removal of natural outlet resistance at the pylorus, either with pyloroplasty or gastrojejunostomy. Similarly, the renal pelvis begs the omission of outlet resistance by pyeloplasty to get improved drainage.

We believe that pyeloplasty restores the pyeloureteral drainage necessary for the improvement of renal function. However, in our study, SRF improved only in 62.3% units. So, why is the improvement not present in all units?

Leahy et al.[21] show complete reversibility in renal function after the release of partial obstruction of 14-day duration. However, reversibility becomes 31% and 8%, if the same obstruction persists up to 28 and 60 days, respectively. They conclude that reversibility depends on the duration of the obstruction, and obviously, earlier relief betters reversibility.

In our study, 26 units had preoperative SRF >30% which seems to be the obstruction of lesser duration. They had better parenchymal reversibility [Table 1]. Other authors have documented similar observation.[222324] Logically greater amount of functional loss indicates obstruction either of long duration or on the severity of obstruction. Hence, obstruction of long duration may reverse less.[25] Nevertheless, one patient had pyeloplasty at 3.5 years of age with GFR of 7.74 and SRF 11.86%, improved to GFR 36.92 and SRF 40.08% following 12 months of pyeloplasty!

CONCLUSIONS

This novel technique singles out the 'renal factor', 'surgical factor' responsible either for bad or good outcomes. Thus, concerned surgeons, pediatricians, and parents would be relieved of vagaries of outcome inherent in pyeloplasty, provided counseling is done based on the hypothesis tested in this study.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.