[Hypertension following blunt kidney injury]

The incidence of hypertension after blunt renal injury is reviewed on the basis of the available literature in English and Danish from 1934 to the present day. The selected literature fulfills defined requirements as regards quality. Hypertension develops one to two days after the trauma and this remits spontaneously after an average of 29 (7-50) days. The reason for this is a perirenal haematoma which produces ischaemic renal tissue by compression after which the haematoma is resorbed. This is demonstrated by urography and investigation of the renin-angiotensin system. The frequency is stated to be 6.7% in an isolated investigation but this must be regarded with reservation. A considerably longer period after the trauma, permanent hypertension develops. This is due to permanent pathological changes which produce ischaemic renal tissue by compression or stenosing of the lumina of the renal arteries. The frequency of this type of hypertension is so low that it cannot be estimated on the basis of the follow-up examinations carried out. These show a frequency of hypertension of between 2.3 and 3.8% which may be explained by the development of spontaneous hypertension. A definite relationship between permanent hypertension and blunt renal injury has only been found in 28 case reports.