Long-term functional and morphological outcome after pyeloplasty for huge renal pelvis

Authors


Osama M. Sarhan, Urology and Nephrology Center, Mansoura University, Mansoura 35516, Egypt. e-mail: o_sarhan2004@yahoo.com

Abstract

Study Type – Therapy (case series)

Level of Evidence 4

OBJECTIVE

• To evaluate the functional and morphological outcome after open pyeloplasty for ureteropelvic junction obstruction (UPJO) with huge renal pelvis.

PATIENTS AND METHODS

• A retrospective review of all cases who underwent pyeloplasty for huge renal pelvis was conducted.

• Records were evaluated with respect to age at presentation, preoperative imaging, surgical details and postoperative course. Patients were followed up regularly for both functional and morphological outcome.

• Success was defined as both symptomatic relief and radiographic resolution of obstruction at last follow-up.

RESULTS

• Between 1998 and 2008, 526 cases of primary UPJO underwent open dismembered pyeloplasty at our centre.

• Of these patients, 41 (8%) had UPJO with huge renal pelvis.

• No perioperative complications were encountered in the study group. Mean (range) follow-up was 34 (18–84) months and nine patients were lost to follow-up. The overall success rate was 91%.

• Two patients underwent redo pyeloplasty, whereas secondary nephrectomy was necessary in one.

• Improvement of hydronephrosis was evident in all patients, except in three patients who underwent secondary procedures.

• However, persistent obstruction on diuretic renography was seen in most cases (65%).

CONCLUSIONS

• Open pyeloplasty for huge pelvis UPJO is feasible with a high success rate.

• Varying degrees of hydronephrosis and radiological obstruction after pyeloplasty are not uncommon.

• Nephrectomy is rarely indicated in cases with severely deteriorated renal function.

Abbreviations
DRF

differential renal function

DTPA

diethylene triamine pentaacetic acid

MRU

magnetic resonance urography

UPJO

ureteropelvic junction obstruction

INTRODUCTION

Ureteropelvic junction obstruction (UPJO) is one of the most common congenital urological anomalies in paediatric urology. The management of such a pathology is essentially surgical, either by an open or laparoscopic approach. Anderson–Hynes dismembered pyeloplasty [1] is the standard procedure performed, together with resection of the dilated renal pelvis. However, surgery can sometimes be challenging, especially if the kidney and renal pelvis are dilated massively, and reconstruction of the UPJ alone is usually inadequate to improve drainage from the pelvicalyceal system. Nephroplication and nephropexy are useful adjuncts to improve drainage after the relief of obstruction in these kidneys [2,3].

Giant hydronephrosis is the massive dilation of the kidney and renal pelvis, such that it occupies most of the hemi-abdomen. It has been defined grossly as having >1 L of fluid within the collecting system and radiographically when the hydronephrotic kidney meets or crosses the midline, occupies a hemi-abdomen, or spans more than five vertebral lengths [4–6]. Most giant hydronephrotic kidneys are non-functional and symptomatic, making nephrectomy the procedure of choice [7]. The incidence of nephrectomy for giant hydronephrosis varies in the range 3–70%[1,7–9].

There have been reports of functional giant hydronephrotic kidneys treated with reconstructive management [1,2,6,10,11]. These studies had several limitations, including the small number of patients, a short follow-up and a lack of functional evaluation [1–3]. In the present study, we report and discuss the surgical treatment and long-term outcome of patients with severe hydronephrosis secondary to UPJO at our institute. We have also evaluated the impact of some patient and kidney characteristics on the success of this procedure.

MATERIALS AND METHODS

We performed a retrospective review of children who underwent open pyeloplasty for huge renal pelvis at our centre between 1998 and 2008. Medical records were evaluated with respect to age at presentation, gender, presenting symptoms, affected side, preoperative imaging, surgical details and postoperative course. Only cases with primary unilateral UPJO with huge renal pelvis were included, whereas patients with bilateral UPJO, UPJO in solitary kidney and recurrent cases were excluded from the study.

Preoperative radiology included renal ultrasound, magnetic resonance urography (MRU) and diuretic renography for all patients. Diethylene triamine pentaacetic acid (DTPA) scans were performed preoperatively and 6 months after pyeloplasty to evaluate drainage and assess renal function. Drainage was classified as good if T½ was <20 min; fair if T½ was >20 min and the drainage curve was descending; or poor if T½ could not be counted and there was an increasing drainage curve. The kidney function was classified as good if split renal function was ≥40%, or poor if <40%. All patients showed marked hydronephrosis with thinning of renal parenchyma of the affected side on both ultrasound and MRU. In addition, all patients had obstructive renal pattern on DTPA scans. The mean (range) split function of the obstructed unit on diuretic renography was 29% (16–43%).

Open Anderson–Hynes dismembered pyeloplasty was carried out for all cases. Nephroplication and nephropexy were carried out in four patients as an adjunct to pyeloplasty to improve drainage. Postoperatively, all patients had external nephroureterostomy stents for an average of 2 weeks.

Patients were followed up regularly clinically and radiologically by serial ultrasound, diuretic renography and MRU for both functional and morphological outcome. Success was defined as both symptomatic relief and radiographic resolution of obstruction at last follow-up.

Data were collected and processed using SPSS, version 13 (SPSS Inc., Chicago, IL, USA). A univariate analysis was used to assess the possible prognostic factors for the success of pyeloplasty by chi-squared. P < 0.05 was considered statistically significant.

RESULTS

During this period, 526 cases of primary UPJO underwent open dismembered pyeloplasty at our centre. Of these patients, 41 (8%) had UPJO with huge renal pelvis (30 males and 11 females; age range 3–120 months). Modes of presentation include antenatal diagnosis, abdominal mass, abdominal pain and urinary tract infection. Table 1 provides a detailed account of the profile of the patient data.

Table 1. Demographic and operative data of the initial intervention
VariablesPatients, n (%)
Gender 
 Boy26 (81.3)
 Girl 6 (18.7)
Age 
 Below 1 year14 (43.8)
 Above 1 year18 (56.2)
Affected side 
 Right17 (53)
 Left15 (47)
Presentation 
 Antenatal diagnosis10 (31)
 Abdominal pain 7 (22)
 UTI 8 (25)
 Palpable mass 7 (22)
Split function (%)29 (16–43)
Pelvis anterior–posterior diameter (mm)56.3 ± 10.2
Parenchymal thickness (mm) 5 ± 2.8

No perioperative complications were encountered in the study group. Mean (range) follow-up was 34 (18–84) months and nine patients were lost to follow-up. The overall success rate was 91%. Two patients underwent redo pyeloplasty, whereas secondary nephrectomy was necessary in one. The remaining patients showed stability or improvement of split renal function on radiological follow-up with no further symptoms.

We found that the anterior–posterior diameter of the renal pelvis showed improvement of varying scale in all patients after pyeloplasty, except in the three patients who underwent secondary procedures. The MRU showed the same findings and it was superior in morphology than ultrasound (Figs 1 and 2). By contrast, postoperative diuretic renography showed normal drainage in only 35% of cases and prolonged drainage was observed in most cases (65%). Postoperative differential renal function (DRF) improved in 16 patients (50%), remained stable in 13 (41%), and deteriorated in three (9%). The degree of DRF improvement was in the range 4–18% (Fig. 3). Postoperative changes in renal ultrasound and diuretic renography are presented in Table 2.

Figure 1.

a, Preoperative MRU axial image showing marked hydronephrosis of the left kidney with huge renal pelvis occupying most of the abdomen and crossing the vertebral column. b, Postoperative MRU axial image of the same patient showing a significant reduction in hydronephrosis, as well as the anterior–posterior diameter of the left renal pelvis with preserved renal parenchyma 1 year after pyeloplasty.

Figure 2.

a, Preoperative MRU coronal image in a 2-year-old girl with a markedly enlarged right kidney and advanced hydronephrosis, with hugely dilated renal pelvis crossing the midline and extending to the iliac region. b, Postoperative gadolinium enhanced MRU image of the same patient 6 months after pyeloplasty showing adequate excretory function of the right kidney with residual dilatation at the malrotated pelvicalyceal system. The ipsilateral ureter is seen to be adequately opacified with contrast.

Figure 3.

a, Preoperative diuretic renography showing the accumulation of tracer activity in the enlarged right kidney with impaired excretion and an obstructed curve. b, Postoperative diuretic renography of the same patient 18 months after right pyeloplasty showing a reduction in kidney size and improved DRF with non-obstructed drainage.

Table 2. Postoperative changes in renal ultrasound and diuretic renography
VariableImproved, n (%)Stable, n (%)Worsened, n (%)
Postoperative hydronephrosis22 (69) 7 (22)3 (9)
Postoperative differential renal function16 (50)13 (41)3 (9)
Postoperative renal drainage12 (37.5)14 (44)6 (18.5)

We also studied the effect of patient age at presentation, clinical presentation, ultrasound findings and preoperative DRF on the final functional outcome after pyeloplasty, although we did not find any statistical significant correlation between these factors and the success of pyeloplasty (Table 3).

Table 3. Univariate analysis of preoperative factors in relation to the final functional outcome
VariableFailed pyeloplasty P
YesNo
Age   
 Below 1 year0140.109
 Above 1 year315
Ultrasound findings   
 Right1160.471
 Left213
Parenchymal thickness   
 <5 mm2120.238
 >5 mm117
Split function (DRF)   
 <30%1100.968
 >30%219
Clinical presentation   
 Antenatal diagnosis190.321
 Abdominal pain07
 UTI17
 Palpable mass16

DISCUSSION

Giant hydronephrosis is the massive dilatation of the kidney and renal pelvis, such that it occupies most of the hemi-abdomen [4,8]. In children, the radiological finding used to define giant hydronephrosis is a kidney that occupies at least half the abdomen, meets or crosses the midline, or spans at least five vertebral lengths [4,8]. Most cases of giant hydronephrosis are the result of UPJO, which is the aetiology in 80% of cases and is usually diagnosed and treated in infancy or childhood. Most giant hydronephrotic kidneys are non-functional, making nephrectomy the procedure of choice [4,7,8,10]. However, attempts at the reconstruction of functional kidneys have been made [1–3,6,10,11]. Restoration of functional and anatomic changes in these cases is the main stay for management. In the present study, we evaluated the surgical reconstruction and outcome of giant hydronephrosis secondary to UPJO.

In the last decade, we evaluated all cases with primary UPJO preoperatively using renal ultrasound, MRU and diuretic renography. MR urography combines high-quality anatomic and functional imaging in a single study that allows the UPJ obstruction to be characterized as either compensated or decompensated hydronephrosis, as well as identifying other pathologies that could influence prognosis [12]. In addition, multiplanar MRI showed the location and extent of the hydronephrotic kidney in better detail. MRI is also helpful in the differentiation of a giant hydronephrosis from a cystic neoplasm or a large renal cyst [13].

Follow-up usually comprises serial renal ultrasound and diuretic renography after 6 months, whereas MRU is carried out when we suspect persistent obstruction by ultrasound. In these cases, we compare the MRU before and after surgery to judge any improvement of hydronephrosis. The success of surgery is usually shown radiographically by decreased hydronephrosis on serial renal ultrasound and by improvement in drainage and/or function on the postoperative diuretic renogram.

Renal ultrasonography is recommended 4–6 weeks after pyeloplasty or stent removal to ensure that hydronephrosis is improving. However, in many patients with successful surgical outcomes, hydronephrosis persists for a long time after the pyeloplasty [14–16]. Improvement in hydronephrosis after pyeloplasty is gradual, usually occurring over a period of many months. Ultimate improvement to grade 0 or 1 was noted in only 19% of cases by Amling et al. [14]. Moreover, when high-grade hydronephrosis persists without any obstructive pattern on radioisotope study, surgical success is difficult to define.

The major concern of surgeons is to recognize when the kidney remains truly obstructed after pyeloplasty. Usually, the renal obstruction is diagnosed by prolonged drainage on DTPA diuretic renography. However, Amarante et al. [17] reported that impaired renal drainage should not be used as a sign of obstruction in children with unilateral hydronephrosis. Neither the degree of renal pelvis dilatation on ultrasound, nor obstruction on diuretic renography was a reliable indicator after pyeloplasty [18,19]. A study by McAleer et al. [20] concluded that renal function did not improve after pyeloplasty, regardless of the initial level of renal function. In another study by Ylinen et al. [21], no improvement was reported to occur in the kidney with <30% preoperative DRF, regardless of successful surgical correction.

Wang et al. [22] reached the conclusion that renal pelvis anterior–posterior diameter and differential renal function should be considered when postoperative obstruction is diagnosed using the criterion of prolonged renal drainage on diuretic renography. In the present study, we confirmed the importance of the stability of DRF and improvement in the anterior–posterior diameter of renal pelvis as indicators for successful pyeloplasty. By employing standard diuretic renography protocols and using the same radiopharmaceutical for each individual, as well as by making efforts for patient hydration and bladder drainage, the results obtained will be more reproducible and compatible.

Several studies have discussed the factors affecting the final functional outcome after pyeloplasty in children [20,21,23–30]. It was concluded that patient age, clinical presentation and ultrasound findings had no impact on functional outcome after pyeloplasty. The same conclusions were reached in the present study.

Some studies have reported on the effect of nephroplasty or nephroplication for reducing intrarenal dilatation and improving drainage [1–3]. Hemal et al. [2] reported that nephroplication and nephropexy were useful adjunctive procedures when treating cases of giant hydronephrotic kidney to reduce pelvicalyceal system stasis and improve drainage, thereby preventing subsequent stone formation, infection and deterioration in renal function. In the present study, we performed nephroplication for four of the 41 patients and the outcome appeared to be no different from those who did not have nephroplication. The number of cases in the present study is too small to show any statistically significant improvement in the results.

The surgical treatment of UPJO with huge renal pelvis remains challenging. Successful pyeloplasty results in the relief of symptoms and an improvement in renal drainage; however, not all kidneys show improvement after surgery. The most important issue is to recognize children who require further surgery for recurrent obstruction during the follow-up period, with the aim of sparing kidneys from nephrectomy.

Although challenging, open pyeloplasty for huge pelvis UPJO is feasible, with a high success rate. Varying degrees of hydronephrosis and impaired drainage after pyeloplasty are not uncommon. Relief of obstruction is best judged by the decrease in anterior–posterior diameter on renal ultrasound and the stability of differential renal function on diuretic renography. Nephrectomy is rarely indicated in cases with severely deteriorated renal function.

CONFLICT OF INTEREST

None declared.

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