[Severe primary congenital unilateral hydronephrosis. A review of 98 cases]

Currently, consensus is lacking on the indications for surgery in primary congenital unilateral hydronephrosis.

To analyze the clinical characteristics, treatment and outcome of severe asymptomatic primary congenital unilateral hydronephrosis (grades 3 and 4).

We performed a retrospective study of 98 neonates with severe primary congenital unilateral hydronephrosis. Diagnostic techniques consisted of ultrasound, renogram, and DMSA scan.

The mean age at diagnosis was 24 days. The mean length of follow-up was 4 years. Forty-eight percent of cases were grade 3 and the remaining cases were grade 4. Fifty-six percent of the patients received conservative treatment. Forty-four percent underwent surgery. Surgical indications consisted of prolonged T1/2, reduced differential renal function and/or very severe hydronephrosis. The mean age at surgery was 5.5 months. In 94 % of the patients who received conservative treatment, hydronephrosis resolved spontaneously. In this group, renal parenchyma and renal function were normal in all patients except two. In 97 % of the patients who received surgical treatment, hydronephrosis was corrected or improved after pyeloplasty. At diagnosis, 19 kidneys had reduced function. In the postsurgical renogram, although T1/2 had markedly improved, 8 kidneys showed reduced function. DMSA performed in 63 patients belonging to both groups, outside the active phase of hydronephrosis, revealed 8 atrophic kidneys, 4 with moderately reduced renal size and function and 4 with scarring and normal renal size and function. During the study period, overall function was maintained in all patients and none developed hypertension.

Severe congenital unilateral hydronephrosis resolves spontaneously in most patients. Consequently, clinicians increasingly adopt a conservative approach. The available diagnostic techniques cannot identify patients who will benefit from pyeloplasty. In general, accepted surgical indications are an increase in hydronephrosis and/or worsening of renal function. In our series, 15 % of the patients with hydronephrosis had an irreversible lesion of variable severity, which in some patients seemed to have developed during embryogenesis. Kidneys at risk of presenting a lesion were those that had grade 4 hydronephrosis.