Acute nondilated anuric obstructive nephropathy on echography: difficult diagnosis in the intensive care unit.

Renal echography (RE) is a well recognized, accurate, non-invasive imaging procedure for detecting urinary tract (UT) obstruction in Intensive Care Unit (ICU) patients: a dilated collecting system is usually present but a few cases of nondilated obstructive nephropathy have been previously described. We report the clinical, biological, imaging procedure data and outcome of 6 additional cases of anuric obstructive nephropathy without dilatation on one or more RE. All patients had previous and/or actual history suggestive of UT obstruction. Retrograde ureteropyelography (RUP) was performed in all of them: it provided the diagnosis of obstruction in 4 and was immediately followed by dramatic improvement of renal function in all, including the 2 patients with septic shock from proven or suspected UT origin. The cause of obstruction was a neoplastic retroperitoneal process in 4. We conclude that anuric nondilated obstructive renal failure is not uncommon and should be considered in anuric patients when UT obstruction is likely to occur. The sole visualization of a non-dilated collecting system on RE should lead to repeat RE, especially in hypovolemic anuric patients. RUP provided immediate diagnostic and therapeutic benefits in comparison with other imaging procedures in our series.