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Long-term Follow-up of Primary Obstructive Megaureter
Liza M. Aguiar, MD1, Dacia Di Renzo, MD2, Pamela I. Ellsworth, MD1, Pierluigi Lelli Chiesa, MD2, Anthony A. Caldamone, MD1.
1Pediatric Urology, Brown University and Hasbro Children's Hospital, Providence, RI, USA, 2Pediatric Surgery, D'Annunzio University and Spirito Santo Hospital, Chieti-Pescara, Italy.


Introduction and Objective: The aim of this study was to evaluate outcomes of non-operative management of primary obstructive megaureter (POM) at long-term follow-up, and to identify risk factors associated with the need for surgical correction.
Methods: After IRB approval, 88 POM diagnosed between 1990 and 2005 at two institutions were studied. Indications for surgery were high grade obstructive hydroureteronephrosis, renal function impairment, or persistent symptoms. Otherwise, patients were managed non-operatively, with follow up ranging between 5 and 15 years. Complete resolution was defined as residual hydronephrosis grade < 2 and retrovesical ureter diameter < 7mm. Hydronephrosis grade, POM type (using the Pfister-Hendren's Classification), differential renal function, age, and mode of presentation (presence or absence of symptoms) were analyzed. These subgroups were compared with Fisher’s exact test to identify factors that are predictors of spontaneous resolution.
Results: At long term follow-up, 54 of 88 POM (61.4%) were managed non-operatively. Complete resolution was documented in 47 of 54 (87%). The remaining 7 (13%) are still followed for mild residual asymptomatic hydroureteronephrosis. All 54 are asymptomatic, with stable renal function. A total of 34 of 88 POM (38.6%) required surgery. In 14 of these 34 (41%), correction was early after diagnosis. Twenty, who were initially observed, required surgery; 12 (35%) within 3 years follow-up and 8 (24%) >= 3 years follow-up. Five patients were corrected under 2 months of age because of compromised renal function, bilateral in 2 patients and in a solitary kidney in 1. Surgery was not required in 80% of cases presenting with hydronephrosis grade <3 versus 46% >= 3 (p=0.0019), 72% of type I and II POM versus 12% of type III (p=0.0001), 0% of renal units with function <40% versus 71% >=40% (p=0.0010), and 70% of prenatally diagnosed POM versus 49% diagnosed postnatally (p=0.0471). Outcomes are summarized in Table 1.
Conclusions: Nonoperative management of POM is a viable option. Most cases of POM remain stable or improve without loss of renal function or development of symptoms. Residual hydroureteronephrosis is most often mild, asymptomatic, and not associated with renal function impairment. In some cases, surgical correction is necessary to prevent further renal function deterioration or because of persisting symptoms. Nevertheless, a careful observational period allows surgery to be delayed beyond the neonatal period. Long-term follow-up is always recommended because worsening of obstruction and impairment of function can develop years later and require surgical correction. Hydronephrosis grade <3, type I or II POM, renal function >=40%, and prenatal presentation are predictors of spontaneous resolution. Mode of presentation does not influence resolution rate.
Table 1: Analysis of subgroups according to parameters at presentation.
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Hydronephrosis gradePOM typeDifferential renal functionAge at presentationMode of presentation
<3>=3I-IIIII<40%>=40%PrenatalPostnatalSymptomaticAsymptomatic
Surgery8262014122015191222
Observation322252204936181242
P value0.00190.00010.00100.0471ns

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