Frank Collier

Predicting the clinical outcome of antenatally detected unilateral pelviureteric junction stenosis.

OBJECTIVE To determine, in children with antenatally detected pelviureteric junction (PUJ) stenosis, what factors may be predictive for deterioration of differential renal function (DRF) in case of conservative treatment or improvement of DRF in case of pyeloplasty. METHODS This study analyzed and compared the initial level of hydronephrosis, DRF, quality of renal drainage, and cortical transit with the late DRF outcome. We reviewed the medical charts of 161 consecutive children with antenatally diagnosed PUJ stenosis during a 10-year period (between 1997 and 2007). From this cohort, we retained 81 children with unilateral PUJ and strictly normal contralateral kidney, with a median follow-up of 67 months. Repeated ultrasounds, voiding cystourethrography, and radionuclide renograms were performed in all children. RESULTS Fifty patients never underwent a surgical intervention (62%), whereas surgical repair (Anderson-Hynes dismembered pyeloplasty) was performed in 31 (38%). During conservative follow-up, DRF deterioration was observed in 11% of patients. After pyeloplasty, DRF improvement was observed in 25% of patients. Abnormal cortical transit was the only predictive factor of DRF deterioration in case of conservative approach, whereas the initial degree of hydronephrosis, or renal drainage, and the initial DRF level were not predictive. In children who were operated on, only impaired cortical transit was predictive of DRF improvement postoperatively. CONCLUSION Conservative management of children with unilateral PUJ stenosis is a safe procedure. Impaired cortical transit although imperfect, seems the best criterion for identifying children for whom pyeloplasty is warranted.

Can severely impaired cortical transit predict which children with pelvi-ureteric junction stenosis detected antenatally might benefit from pyeloplasty?

IntroductionUntil recently, renogram, performed in children with pelvi-ureteric junction stenosis detected antenatally, has not been able to predict the probability of function improvement after surgery or the risk of function deterioration in case of conservative attitude. Recently, Schlotmann et al. have suggested that cortical transit might have this predictive role. The aim of this study, focused on those kidneys with severely impaired cortical transit, was to verify this statement. MethodsAll renograms performed in children during a 3-year period (n=729) were retrospectively reviewed and 19 pediatric patients were selected based on an antenatally detected unilateral pelvi-ureteric junction syndrome, the existence of at least two renograms during the follow-up and a severe cortical transit impairment, visually defined. Twenty-six pairs of data could be analyzed and allowed comparing preoperative and postoperative differential renal function (DRF), and the DRF changes during the conservative management. ResultsAmong the 16 patients who underwent pyeloplasty, 10 showed a significant DRF improvement. Among the 10 patients with conservative follow-up, four showed a significant DRF deterioration. ConclusionSeverely impaired cortical transit seems to be a valuable marker of those patients who could benefit from a pyeloplasty, either because of the high probability of postoperative DRF improvement, or because of DRF deterioration in case of an conservative approach. However, a normal cortical transit, as defined in this study, does not exclude the risk of DRF deterioration. Alternatively, the design of this study does not allow excluding the fact that DRF might improve after pyeloplasty despite a normal cortical transit.

Prospective management of neonates with pelviureteric junction stenosis. Therapeutic strategy based on 99m Tc-DPTA studies

A prospective therapeutic strategy based on separate glomerular filtration rate (SGFR) was evaluated in 14 prenatally detected asymptomatic neonates, suspected of having pelviureteric junction obstruction. The patients with low SGFR were referred for pyeloplasty with the hope to improve the renal function. A marked improvement occurred in only one patient, although the drainage function (furosemide test) did improve in all cases. A conservative attitude was adopted for those children with normal SGFR. In 6 of them, a progressive increase of SGFR was noted, related to the normal maturation of the function, followed by a stabilization in the normal range. In 1 patient, a sudden decrease of SGFR was observed around 1 year and the patient was shifted into the surgical group. In this patient, an initial partial response of the kidney to a furosemide injection changed into a persistent non-response, whereas in the other non-operated patients, partial or good response was always recorded, although the responses were essentially variable on successive tests. On the basis of these data, the protocol was slightly modified, the patients with persistent non-response to furosemide after 6 months of life being shifted to the surgical group.

Renal duplications : the impact of perinatal ultrasound on diagnosis and management

Perinatal urology is a rapidly expanding field in pediatric urology bringing significant changes in the diagnosis and management of congenital uropathies. Renal duplication was detected by antenatal and perinatal ultrasound in 19 cases (22 duplicated systems). In most cases, no precise diagnosis could be established in utero (4 of 13), but this lack of accuracy is of little clinical significance since all newborns with suspected uropathies undergo complete urological investigations in the perinatal period. Voiding cystogram demonstrated reflux in 11 of 22 cases. On postnatal urography a functioning upper pole was demonstrated in 11 of 22 kidneys. There were 12 ureteroceles: in 8 a nonfunctioning upper pole was removed, while 3 were endoscopically incised with good functional improvement and 1 was reimplanted. Early recognition of congenital uropathies in association with duplication by prenatal ultrasound significantly improves patient care allowing early postnatal relief of obstruction by less invasive methods and before infection or persistent obstruction worsens the prognosis.

LONG-TERM FOLLOW-UP OF SEPARATE GLOMERULAR FILTRATION RATE IN PARTIALLY OBSTRUCTED KIDNEYS

An often encountered assumption is that non-relieved renal obstruction will lead soon or late to progressive deterioration of the renal function. The effect of non-relieved partial ureteral obstruction on the separate glomerular filtration rate (SGFR) was studied throughout the whole life of a series of rats, who were submitted at the age of 3 months to partial obstruction of the left ureter. An initial and variable postoperative SGFR decrease was gradually observed, but after this period, SGFR remained stable until the natural death of the animal.

99Tcm-DMSA uptake in obstructed kidneys. How inaccurate are the 5 h measurements?

Partial obstruction of the left ureter was created in 19 rats and a relative 99Tcm-DMSA uptake was obtained 5 and 24 h after intravenous injection of the tracer. A systematic and variable overestimation of the left to right uptake ratio was found at 5 h, with a mean error of 15.8% (S.D. = 12.2).

Radioisotopic evaluation of the renal parenchymal function in children with ureteropelvic junction obstruction. A retrospective study.

Separate glomerular filtration rates were evaluated in 21 children with uni- or bilateral ureteropelvic junction stenosis, using the Tc-99m DTPA complex and the scintillation camera.The grade of alteration seen on urograms has influenced the surgeon in his decision to use a conservative or a surgical treatment, whereas the type of intervention (pyeloplasty or nephrectomy) was mainly based on the scintigraphic quantitation. The morphological data provided by an excretory urogram could not predict the degree of functional impairment.The scintigraphic evaluation of single kidney clearance was useful in the evaluation of the effects of medical and surgical treatment.

Technetium-99m DMSA imaging and the obstructed kidney

Although several authors have claimed that the function of an obstructed kidney could be overestimated on Tc-99m DMSA imaging, the clinical importance of such an overestimation has not been well documented. Partial obstruction of one ureter was created in a rat, and a relative Tc-99m DMSA uptake was obtained 4 hours after intravenous injection. By puncture of the isolated obstructed kidney, it was shown that the function of that kidney was overestimated by at least 17%.

Sensitivity of Cortical Transit and Furosemide Response in the Diagnosis of Renal Obstruction. An Experimental Model

Several radionuclide parameters are routinely used for the diagnosis of renal obstruction. In order to evaluate the sensitivity of those parameters, an experimental model of partial ureteral obstruction in rats was used. Neither the cortical transit time, nor the response to furosemide could serve to discriminate between obstructive and nonobstructive kidneys. These parameters were, however, more or less related to the degree of impairment of the single kidney glomerular filtration rate and should probably be considered as functional parameters reflecting the grade of the obstructive phenomenon.

Effect of hyperfiltration on long-term follow-up of glomerular filtration rate in male Wistar rats

It has been suggested that a prolonged course of hyperfiltration could lead to progressive deterioration of renal function. In order to test this hypothesis, the following protocol was applied to 60 male Wistar rats. At 12 weeks of life, the rats were submitted to a surgical procedure: sham operation (25 rats), unilateral nephrectomy (25 rats) or 3/4 nephrectomy (10 rats). The three groups were again divided into two subgroups: one with high-protein intake (36%) and one with a low-protein intake (12%). In order to avoid any additional traumatic procedure which could shorten the animals life, the glomerular filtration rate (GFR) was measured without blood sampling, using a previously validated technique based on an image recorded by a gamma camera between the 9th and the 10th min after intravenous injection of99m technetium diethylenetriaminepentaacetate (DTPA). The sum of both kidneys and bladder activity was expressed as a percentage of the injected dose. The test was performed before surgery and every month thereafter. Six weeks after surgery, the highest filtration rate was found in the rats with “two kidneys/high-protein diet”, followed by the “two kidneys/low-protein diet”, the “one kidney/high-protein diet”, the “one kidney/low-protein diet” and the “1/2 kidney”. The overall GFR in the one kidney/high-protein diet rat and in the 1/2 kidney rat was respectively 80% and 55% of the pre-operative values. Until 109 weeks of age, the survival rate was comparable in the five groups of rats. At 109 weeks of age, non-significant changes in renal function were observed, the follow-up slopes of the different subgroups being more or less parallel. At that age, the lesions of glomerular sclerosis were focal and discrete, without significant differences in the five groups.