Influence of induced intrauterine diuresis on the upper urinary tract

There are many possible etiologies of sonographically detected dilatation of the renal pelvis and the ureter during pregnancy. The observation that fetal ureteral dilatation occurs with congenital diabetes insipidus has led to the suspicion of at least a modifying influence resulting from intrauterine diuresis. To increase fetal diuresis experimentally, Wistar rats were treated with 100 mg chlorthalidon and 40 mg furosemide per kg bodyweight per day. The animal experiment was performed with four groups. Group I was treated during the entire course of pregnancy. Group II during the first half and Group III during the second half. Group C was the untreated control group. For morphometric investigation, nine equidistant sections of each ureter were prepared. Circumference and submucosal muscle and urothelial thickness were determined and evaluated by means of variance analysis. Statistically significant changes were found only in the upper third of the ureter. The increase in circumference was highly significant in all treated groups. Dilatation found in the upper third of the ureter can most likely be explained as a result of the increased intrauterine diuresis. On the basis of these results, however, it does not appear necessary to require complete restriction of diuretics during pregnancy.