The influence of hydration and bladder distension on the sonographic diagnosis of hydronephrosis.

Renal sonography is frequently employed to exclude obstructive uropathy in patients with uremia. Sonographic findings of moderate bilateral hydronephrosis were encountered in a dehydrated patient undergoing rehydration. Subsequent excretory urography and a follow-up renal sonogram were normal. To investigate the possibility that hydration and bladder distension in an otherwise normal and unobstructed collecting system could result in hydronephrosis detectable by ultrasound, 23 apparently normal volunteers underwent renal sonography in the hydrated and basal states. The filled urinary bladder in a patient undergoing hydration frequently results in the sonographic appearance of hydronephrosis.