Delayed hypertension after blunt renal trauma.

Severe hypertension developed in 4 patients who had sustained blunt renal trauma 2-32 years previously. A protracted period of normal blood pressure separated the renal injury from the onset of hypertension. Angiography disclosed lesions which had been underestimated by intravenous pyelography. These lesions consisted of traumatic dissection of branches of the renal artery, leading to renal infarct. In 3 cases, unilateral high renin secretion was demonstrated, and in 1 case this was confirmed by immunofluorescence with an anti-renin antiserum which showed abundant renin granules within the infarcted zone. In all patients, total or polar nephrectomy was followed by return of blood pressure to normal or near-normal levels. Blunt renal trauma is an underestimated cause of renovascular hypertension.