Acute hemodynamic and endocrinological effects of partial fetal bladder obstruction

The pathophysiology of fetal urinary obstruction has not been elucidated. Using a unique, reproducible and easily reversible animal preparation, we studied the acute hemodynamic and endocrinological responses to partial fetal bladder obstruction in 16 ovine fetuses at 115 days of gestation (term 147 days). After partial obstruction blood pressure and renal weight increased significantly for at least 72 hours. Renal blood flow trended upwards, particularly from 24 to 72 hours, although this change was not statistically significant. Plasma renin activity was significantly increased during the first 24 hours after obstruction but it returned to baseline thereafter. Plasma cortisol or catecholamine concentrations remained unchanged. The time course and pattern of hemodynamic changes in this fetal sheep preparation of partial urinary obstruction differ significantly from those reported in other preparations.