Sonography after renal biopsy: assessment of its role in 230 consecutive cases

Among 230 patients undergoing ultrasound (US) guided renal biopsy, 218 had postbiopsy sonography. Clinical records were reviewed to correlate symptoms to US findings. In each case of large hematoma (thickness above 1 cm), all postbiopsy sonographic studies were analyzed to look for findings indicative of unfavorable outcome. A total of 96 subcapsular/perirenal hematomas were found. Large hematomas were observed in 20 patients (20/230 = 8.7%), seven of these (3%) were severely symptomatic. In the absence of clinical signs of bleeding, no patient had clinical consequences. In the presence of clinical signs of bleeding, serious complications occurred only in patients with large hematomas. US thickness of retroperitoneal hematoma correlated to clinical outcome: whenever measured thickness was less than 2 cm, clinical evolution was very favorable, whereas a thickness above 2 cm was invariably associated to clinical signs of bleeding. In six of seven cases of thickness exceeding 3 cm, severe complications developed. An unfavorable evolution was associated with increasing thickness and an echogenicity inappropriate with respect to the time elapsed since biopsy. Hydroureteronephrosis, peritoneal effusion, and anomalous vascular images were indicators of deterioration. We conclude that sonography is indicated only for symptomatic patients and that the monitoring of both thickness and changing echogenicity of retroperitoneal blood collections supplements clinical follow-up.