Introduction: At the end of pregnancy, the amniotic fluid (AF) depends basically on renal function, corresponding to fetal urine. Changes in AF, especially oligohydramnios, are reported in association with fetal hydronephrosis (FH). The experimental model using adriamycin in pregnant female rats has a teratogenic effect and has been classically employed to study esophageal atresia. Nevertheless, adriamycin promotes FH with high frequency as well. In the present study, using this animal model, we tried to identify the incidence and microscopic changes of FH, as well as its correlation with AF weight.
Materials and methods: Eight Spreague-Dawley pregnant female rats received adriamycin 2.2 mg/kg on the 8th and 9th gestational days (considering term gestation = 22 days). Those fetuses that received adriamycin (Adriamycin Group) were compared with fetuses from 2 female rats (Control Group), which received 0.9% saline solution. On the 21.5 gestational day, the fetuses were collected by cesarean incision, sacrificed, and examined for macro and microscopic changes in kidneys and ureters. Fetuses with bilateral hydronephrosis formed the Hydronephrosis Group. AF weight was determined as well.
Results: Hydronephrosis occurred in 70 (95%) of the 74 fetuses in the adriamycin group against none of the 21 fetuses from the control group. The amniotic fluid weight was increased in the adriamycin group in relation to the control group (p < 0.001). The histomorphometric study revealed dilation of the renal pelvis and reduction of renal parenchyma in the hydronephrosis group in relation to the control group. Severe cortical atrophy, cortical tubular atrophy and medullar atrophy were observed in the hydronephrosis group.
Conclusions: Slight renal lesions were in agreement with changes in AF weight, since they suggest that there was production of urine with the maintenance of AF.