Is less more for posterior urethral valves patients?

Some patients with posterior urethral valves fail to improve after primary valve ablation with regards to hydronephrosis and creatinine levels. Because of this, pediatric urologists sometimes recommend either a vesicostomy or in some cases a high diversion (pyelostomy or ureterostomy). However, I believe these extra procedures often fail to improve hydronephrosis or renal function and can potentially be detrimental to future bladder function. In addition, all these additional operations will mandate more future surgeries to deal with complications arising from them — vesicostomy prolapse or stenosis for example — or to undo them.

Beyond ablating the valve, I believe little more can be done for the majority of patients. Hydronephrosis can be impressive and urologists naturally assume the patient is obstructed and that something needs to be done. However, the hydronephrosis is usually non-obstructive and is due to massive amounts of very dilute urine been made by poorly functioning kidneys.

Clinical case

To illustrate the above points, I will talk about a patient of mine. This patient had valves ablated soon after birth and was subsequently followed. His creatinine went up for the first few weeks and then started trending down but never came down to normal levels. His hydronephrosis was very significant on both sides but more so on the left side where he had very little renal parenchyma.

I discussed the case online with several pediatric urologists from around the world and the majority advocated for intervention, either vesicostomy, clean intermittent catheterization or high diversion. Almost no one suggested observation. Time passed and the only thing that was done was that we added Ditropan and kept observing. The patient did well with no UTI’s but eventually required a transplant at around 2 years of age. During the transplant the left kidney was removed but the right one was left because the parenchyma was thought to be healthy.

Months later the right hydronephrosis completely disappeared. Clinically the patient did well after the transplant with stable creatinines, no hydronephrosis on the transplanted kidney, and no UTI’s.

Would a vesicostomy or high diversion have helped this patient? Based on the fact that he has no hydronephrosis now, stable creatinines, no UTI’s, and normal bladder emptying, I think the answer to the question is no. I believe the patient was spared an unnecessary vesicostomy/pyelostomy plus all the subsequent surgeries that would have been required. In addition, his transplant was easier on a virgin abdomen and his bladder function was unaffected.

If the patient had a “bad bladder” that was causing hydronephrosis and elevated creatinine before the transplant, then we should be seeing hydronephrosis and elevated creatinine also after the transplant –which we are not. To reiterate, the fact that things are normal now proves to me that a vesicostomy or pyelostomy would have had been unnecessary procedures.

 

What the literature has to say

This study from Philadelphia compared primary diversion versus primary valve ablation and concluded that vesicostomies or high diversions do little to change the ultimate fate of the patients. In their study, 3 patients had a high diversion with no changes in creatinine and 4 patients had a vesicostomy with only one having an improved creatinine. When the authors compared the 3 primary treatments (valve ablation, vesicostomy or high diversion) using a Kaplan-Mayer curve, they were not able to notice any trends or statistically significant differences.  The authors mentioned that kidneys start increasing their GFR soon after birth and during the first 2 years — transitional nephrology –due to increase blood pressure and decrease intrarenal resistance, which complicates the assessment of the benefit of interventions during this period. They contend that the benefits seen with regards to improving creatinine after high diversion can be attributed to transitional nephrology and can also be seen after valve ablation if one is patient. Not surprisingly, the patients primarily diverted ended up having more procedures done (reimplants, undiversion, etc). The authors concluded there is no advantage to primary diversion compared to primary valve ablation.

Another study from the Mayo Clinic, Rochester also questioned the utility of high diversion for PUV patients. They looked at 26 patients that had high diversion who at the time of reconstruction had a Whitaker test. Only 1 patient had bilateral UVJ obstruction demonstrated objectively. At a median follow up of 9 years, 58% of patients developed end-stage renal disease despite the high diversion questioning the necessity of the procedure. They concluded that failure of the creatinine to normalize with bladder decompression is rarely due to anatomic obstruction of the UVJ and almost always due to congenital renal dysplasia. The authors point out an interesting fact about transitional nephrology where they state that 34-week premature babies have a GFR of only 10 cc/min/m2 and thus premature babies tend to take longer for their creatinines to improve, putting them at higher risk of been diverted because of that. These authors also conclude that similar improvements in creatinine can be achieved after primary valve ablation if one only waits patiently for the transitional nephrologic changes to occur. The authors, however, chose vesicostomy as the primary treatment for all their patients at the time of the study, which is not the current standard.

A more recent abstract from the 2019 SPU meeting, evaluated the risk of renal replacement therapy (RRT) among PUV and Prune Belly patients, to assess if increased prenatal imaging and subsequent intervention have had any effects on RRT. This was a national hospital database study with 940 PUV and 142 PBS patients. Mean follow up was 4.7 years. 15% of patients in the cohort developed ESRD, with almost 80% of them doing so in the first 2 years of life. The authors then stratified the cohort by year from 2006-2012 noting no difference from year to year, suggesting that modifying the natural history of these conditions is difficult.

Studies have also failed to show better outcomes in terms of ESRD/RRT when the diagnosis is made prenatally compared to postnatally.

Lastly, another recent study from the Toronto group looked at the impact of adjuvant urinary diversion versus valve ablation alone on progression from chronic to end-stage renal disease. They compared primary valve ablation alone (14), ablation followed by vesicostomy (13) and ablation followed by upper tract diversion (13). They used Kaplan-Meyer curves (which are essential when comparing outcomes occurring years after the intervention). At 15 year follow up there appear to be no difference in between the treatment groups.

 

Conclusion

The literature suggests that for most patients with posterior urethral valves, little benefit will be achieved by diverting the patient after primary valve ablation. Vesicostomies and high diversions guarantee further operations and can potentially affect bladder function. Sometimes the most difficult thing to do is to do nothing. We should “first do no harm”.

 

 

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