Objective: To investigate the proportion of women with findings characteristic for pre-eclampsia, as opposed to renal disease, in a controlled study of hypertensive pregnant women undergoing antepartum renal biopsy.
Design: An observational prospective controlled study.
Setting: University Hospital of Lund, Sweden.
Sample: Thirty-six previously healthy women with hypertensive disease in pregnancy, consecutively admitted to the antenatal ward at onset of disease during a 20 month period and giving informed consent, as well as 12 voluntary healthy pregnant controls.
Methods: Renal biopsy samples were obtained from all participants and evaluated by light microscopy, electron microscopy and immunofluorescence techniques.
Main outcome measures: Presence and degree of glomerular endotheliosis.
Results: Glomerular endotheliosis was present in all women with pre-eclampsia and gestational hypertension, and in 5 of the 12 controls, although significant differences in the degree of endotheliosis were found between the groups. Clinically undetected renal disease was not diagnosed in any of the women.
Conclusion: Glomerular endotheliosis was found in women with normal pregnancy as well as in both non-proteinuric and proteinuric hypertension and is consequently not, as earlier believed, pathognomonic for pre-eclampsia. The transition between normal term pregnancy, gestational hypertension and pre-eclampsia appears to be a continuous process, perhaps of increasing adaptation to pregnancy. Pre-eclampsia may be the extreme of the adaptational process, rather than a separate abnormal condition. Clinically undetected renal disease could be a rare cause of hypertension in pregnancy.