Structural and functional changes in the renal circulation after complicated pregnancy.

Angiographic and histological studies of the intrarenal circulation have been undertaken in 20 patients following complicated pregnancies: 12 patients had had hypertension of pregnancy (group 1); 7 acute renal failure due to either ante- or post-partum haemorrhage and 1 patient post-partum renal failure (group 2). 3 months after delivery all patients had angiographic evidence of structural and functional abnormalities involving intrarenal blood vessels and cortical blood flow. The severity of the structural changes was related to the degree of microangiopathic haemolytic anaemia noted in the acute obstetric complication but not to the height of the blood pressure at this stage. Histological abnormalities of the cortical blood vessels were minimal. At the time of the renal angiogram and biopsy, 3 of the 12 group 1 patients were hypertensive and 3 had impaired renal function, compared with 5 and 1, respectively, in the 8 group 2 patients. Although during the follow-up period (mean 5 years) no further deterioration in renal function in either group has been observed, hypertension developed in 50% of the group 1 patients compared with only 1 of the patients in group 2. The relationship between the late onset of hypertension and the intrarenal vascular and haemodynamic abnormalities is discussed.